clang  7.0.0svn
RecordLayoutBuilder.cpp
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1 //=== RecordLayoutBuilder.cpp - Helper class for building record layouts ---==//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "clang/AST/RecordLayout.h"
11 #include "clang/AST/ASTContext.h"
12 #include "clang/AST/Attr.h"
14 #include "clang/AST/Decl.h"
15 #include "clang/AST/DeclCXX.h"
16 #include "clang/AST/DeclObjC.h"
17 #include "clang/AST/Expr.h"
18 #include "clang/Basic/TargetInfo.h"
20 #include "llvm/ADT/SmallSet.h"
21 #include "llvm/Support/Format.h"
22 #include "llvm/Support/MathExtras.h"
23 
24 using namespace clang;
25 
26 namespace {
27 
28 /// BaseSubobjectInfo - Represents a single base subobject in a complete class.
29 /// For a class hierarchy like
30 ///
31 /// class A { };
32 /// class B : A { };
33 /// class C : A, B { };
34 ///
35 /// The BaseSubobjectInfo graph for C will have three BaseSubobjectInfo
36 /// instances, one for B and two for A.
37 ///
38 /// If a base is virtual, it will only have one BaseSubobjectInfo allocated.
39 struct BaseSubobjectInfo {
40  /// Class - The class for this base info.
41  const CXXRecordDecl *Class;
42 
43  /// IsVirtual - Whether the BaseInfo represents a virtual base or not.
44  bool IsVirtual;
45 
46  /// Bases - Information about the base subobjects.
48 
49  /// PrimaryVirtualBaseInfo - Holds the base info for the primary virtual base
50  /// of this base info (if one exists).
51  BaseSubobjectInfo *PrimaryVirtualBaseInfo;
52 
53  // FIXME: Document.
54  const BaseSubobjectInfo *Derived;
55 };
56 
57 /// \brief Externally provided layout. Typically used when the AST source, such
58 /// as DWARF, lacks all the information that was available at compile time, such
59 /// as alignment attributes on fields and pragmas in effect.
60 struct ExternalLayout {
61  ExternalLayout() : Size(0), Align(0) {}
62 
63  /// \brief Overall record size in bits.
64  uint64_t Size;
65 
66  /// \brief Overall record alignment in bits.
67  uint64_t Align;
68 
69  /// \brief Record field offsets in bits.
70  llvm::DenseMap<const FieldDecl *, uint64_t> FieldOffsets;
71 
72  /// \brief Direct, non-virtual base offsets.
73  llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsets;
74 
75  /// \brief Virtual base offsets.
76  llvm::DenseMap<const CXXRecordDecl *, CharUnits> VirtualBaseOffsets;
77 
78  /// Get the offset of the given field. The external source must provide
79  /// entries for all fields in the record.
80  uint64_t getExternalFieldOffset(const FieldDecl *FD) {
81  assert(FieldOffsets.count(FD) &&
82  "Field does not have an external offset");
83  return FieldOffsets[FD];
84  }
85 
86  bool getExternalNVBaseOffset(const CXXRecordDecl *RD, CharUnits &BaseOffset) {
87  auto Known = BaseOffsets.find(RD);
88  if (Known == BaseOffsets.end())
89  return false;
90  BaseOffset = Known->second;
91  return true;
92  }
93 
94  bool getExternalVBaseOffset(const CXXRecordDecl *RD, CharUnits &BaseOffset) {
95  auto Known = VirtualBaseOffsets.find(RD);
96  if (Known == VirtualBaseOffsets.end())
97  return false;
98  BaseOffset = Known->second;
99  return true;
100  }
101 };
102 
103 /// EmptySubobjectMap - Keeps track of which empty subobjects exist at different
104 /// offsets while laying out a C++ class.
105 class EmptySubobjectMap {
106  const ASTContext &Context;
107  uint64_t CharWidth;
108 
109  /// Class - The class whose empty entries we're keeping track of.
110  const CXXRecordDecl *Class;
111 
112  /// EmptyClassOffsets - A map from offsets to empty record decls.
113  typedef llvm::TinyPtrVector<const CXXRecordDecl *> ClassVectorTy;
114  typedef llvm::DenseMap<CharUnits, ClassVectorTy> EmptyClassOffsetsMapTy;
115  EmptyClassOffsetsMapTy EmptyClassOffsets;
116 
117  /// MaxEmptyClassOffset - The highest offset known to contain an empty
118  /// base subobject.
119  CharUnits MaxEmptyClassOffset;
120 
121  /// ComputeEmptySubobjectSizes - Compute the size of the largest base or
122  /// member subobject that is empty.
123  void ComputeEmptySubobjectSizes();
124 
125  void AddSubobjectAtOffset(const CXXRecordDecl *RD, CharUnits Offset);
126 
127  void UpdateEmptyBaseSubobjects(const BaseSubobjectInfo *Info,
128  CharUnits Offset, bool PlacingEmptyBase);
129 
130  void UpdateEmptyFieldSubobjects(const CXXRecordDecl *RD,
131  const CXXRecordDecl *Class,
132  CharUnits Offset);
133  void UpdateEmptyFieldSubobjects(const FieldDecl *FD, CharUnits Offset);
134 
135  /// AnyEmptySubobjectsBeyondOffset - Returns whether there are any empty
136  /// subobjects beyond the given offset.
137  bool AnyEmptySubobjectsBeyondOffset(CharUnits Offset) const {
138  return Offset <= MaxEmptyClassOffset;
139  }
140 
141  CharUnits
142  getFieldOffset(const ASTRecordLayout &Layout, unsigned FieldNo) const {
143  uint64_t FieldOffset = Layout.getFieldOffset(FieldNo);
144  assert(FieldOffset % CharWidth == 0 &&
145  "Field offset not at char boundary!");
146 
147  return Context.toCharUnitsFromBits(FieldOffset);
148  }
149 
150 protected:
151  bool CanPlaceSubobjectAtOffset(const CXXRecordDecl *RD,
152  CharUnits Offset) const;
153 
154  bool CanPlaceBaseSubobjectAtOffset(const BaseSubobjectInfo *Info,
155  CharUnits Offset);
156 
157  bool CanPlaceFieldSubobjectAtOffset(const CXXRecordDecl *RD,
158  const CXXRecordDecl *Class,
159  CharUnits Offset) const;
160  bool CanPlaceFieldSubobjectAtOffset(const FieldDecl *FD,
161  CharUnits Offset) const;
162 
163 public:
164  /// This holds the size of the largest empty subobject (either a base
165  /// or a member). Will be zero if the record being built doesn't contain
166  /// any empty classes.
167  CharUnits SizeOfLargestEmptySubobject;
168 
169  EmptySubobjectMap(const ASTContext &Context, const CXXRecordDecl *Class)
170  : Context(Context), CharWidth(Context.getCharWidth()), Class(Class) {
171  ComputeEmptySubobjectSizes();
172  }
173 
174  /// CanPlaceBaseAtOffset - Return whether the given base class can be placed
175  /// at the given offset.
176  /// Returns false if placing the record will result in two components
177  /// (direct or indirect) of the same type having the same offset.
178  bool CanPlaceBaseAtOffset(const BaseSubobjectInfo *Info,
179  CharUnits Offset);
180 
181  /// CanPlaceFieldAtOffset - Return whether a field can be placed at the given
182  /// offset.
183  bool CanPlaceFieldAtOffset(const FieldDecl *FD, CharUnits Offset);
184 };
185 
186 void EmptySubobjectMap::ComputeEmptySubobjectSizes() {
187  // Check the bases.
188  for (const CXXBaseSpecifier &Base : Class->bases()) {
189  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
190 
191  CharUnits EmptySize;
192  const ASTRecordLayout &Layout = Context.getASTRecordLayout(BaseDecl);
193  if (BaseDecl->isEmpty()) {
194  // If the class decl is empty, get its size.
195  EmptySize = Layout.getSize();
196  } else {
197  // Otherwise, we get the largest empty subobject for the decl.
198  EmptySize = Layout.getSizeOfLargestEmptySubobject();
199  }
200 
201  if (EmptySize > SizeOfLargestEmptySubobject)
202  SizeOfLargestEmptySubobject = EmptySize;
203  }
204 
205  // Check the fields.
206  for (const FieldDecl *FD : Class->fields()) {
207  const RecordType *RT =
208  Context.getBaseElementType(FD->getType())->getAs<RecordType>();
209 
210  // We only care about record types.
211  if (!RT)
212  continue;
213 
214  CharUnits EmptySize;
215  const CXXRecordDecl *MemberDecl = RT->getAsCXXRecordDecl();
216  const ASTRecordLayout &Layout = Context.getASTRecordLayout(MemberDecl);
217  if (MemberDecl->isEmpty()) {
218  // If the class decl is empty, get its size.
219  EmptySize = Layout.getSize();
220  } else {
221  // Otherwise, we get the largest empty subobject for the decl.
222  EmptySize = Layout.getSizeOfLargestEmptySubobject();
223  }
224 
225  if (EmptySize > SizeOfLargestEmptySubobject)
226  SizeOfLargestEmptySubobject = EmptySize;
227  }
228 }
229 
230 bool
231 EmptySubobjectMap::CanPlaceSubobjectAtOffset(const CXXRecordDecl *RD,
232  CharUnits Offset) const {
233  // We only need to check empty bases.
234  if (!RD->isEmpty())
235  return true;
236 
237  EmptyClassOffsetsMapTy::const_iterator I = EmptyClassOffsets.find(Offset);
238  if (I == EmptyClassOffsets.end())
239  return true;
240 
241  const ClassVectorTy &Classes = I->second;
242  if (std::find(Classes.begin(), Classes.end(), RD) == Classes.end())
243  return true;
244 
245  // There is already an empty class of the same type at this offset.
246  return false;
247 }
248 
249 void EmptySubobjectMap::AddSubobjectAtOffset(const CXXRecordDecl *RD,
250  CharUnits Offset) {
251  // We only care about empty bases.
252  if (!RD->isEmpty())
253  return;
254 
255  // If we have empty structures inside a union, we can assign both
256  // the same offset. Just avoid pushing them twice in the list.
257  ClassVectorTy &Classes = EmptyClassOffsets[Offset];
258  if (std::find(Classes.begin(), Classes.end(), RD) != Classes.end())
259  return;
260 
261  Classes.push_back(RD);
262 
263  // Update the empty class offset.
264  if (Offset > MaxEmptyClassOffset)
265  MaxEmptyClassOffset = Offset;
266 }
267 
268 bool
269 EmptySubobjectMap::CanPlaceBaseSubobjectAtOffset(const BaseSubobjectInfo *Info,
270  CharUnits Offset) {
271  // We don't have to keep looking past the maximum offset that's known to
272  // contain an empty class.
273  if (!AnyEmptySubobjectsBeyondOffset(Offset))
274  return true;
275 
276  if (!CanPlaceSubobjectAtOffset(Info->Class, Offset))
277  return false;
278 
279  // Traverse all non-virtual bases.
280  const ASTRecordLayout &Layout = Context.getASTRecordLayout(Info->Class);
281  for (const BaseSubobjectInfo *Base : Info->Bases) {
282  if (Base->IsVirtual)
283  continue;
284 
285  CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base->Class);
286 
287  if (!CanPlaceBaseSubobjectAtOffset(Base, BaseOffset))
288  return false;
289  }
290 
291  if (Info->PrimaryVirtualBaseInfo) {
292  BaseSubobjectInfo *PrimaryVirtualBaseInfo = Info->PrimaryVirtualBaseInfo;
293 
294  if (Info == PrimaryVirtualBaseInfo->Derived) {
295  if (!CanPlaceBaseSubobjectAtOffset(PrimaryVirtualBaseInfo, Offset))
296  return false;
297  }
298  }
299 
300  // Traverse all member variables.
301  unsigned FieldNo = 0;
302  for (CXXRecordDecl::field_iterator I = Info->Class->field_begin(),
303  E = Info->Class->field_end(); I != E; ++I, ++FieldNo) {
304  if (I->isBitField())
305  continue;
306 
307  CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
308  if (!CanPlaceFieldSubobjectAtOffset(*I, FieldOffset))
309  return false;
310  }
311 
312  return true;
313 }
314 
315 void EmptySubobjectMap::UpdateEmptyBaseSubobjects(const BaseSubobjectInfo *Info,
316  CharUnits Offset,
317  bool PlacingEmptyBase) {
318  if (!PlacingEmptyBase && Offset >= SizeOfLargestEmptySubobject) {
319  // We know that the only empty subobjects that can conflict with empty
320  // subobject of non-empty bases, are empty bases that can be placed at
321  // offset zero. Because of this, we only need to keep track of empty base
322  // subobjects with offsets less than the size of the largest empty
323  // subobject for our class.
324  return;
325  }
326 
327  AddSubobjectAtOffset(Info->Class, Offset);
328 
329  // Traverse all non-virtual bases.
330  const ASTRecordLayout &Layout = Context.getASTRecordLayout(Info->Class);
331  for (const BaseSubobjectInfo *Base : Info->Bases) {
332  if (Base->IsVirtual)
333  continue;
334 
335  CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base->Class);
336  UpdateEmptyBaseSubobjects(Base, BaseOffset, PlacingEmptyBase);
337  }
338 
339  if (Info->PrimaryVirtualBaseInfo) {
340  BaseSubobjectInfo *PrimaryVirtualBaseInfo = Info->PrimaryVirtualBaseInfo;
341 
342  if (Info == PrimaryVirtualBaseInfo->Derived)
343  UpdateEmptyBaseSubobjects(PrimaryVirtualBaseInfo, Offset,
344  PlacingEmptyBase);
345  }
346 
347  // Traverse all member variables.
348  unsigned FieldNo = 0;
349  for (CXXRecordDecl::field_iterator I = Info->Class->field_begin(),
350  E = Info->Class->field_end(); I != E; ++I, ++FieldNo) {
351  if (I->isBitField())
352  continue;
353 
354  CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
355  UpdateEmptyFieldSubobjects(*I, FieldOffset);
356  }
357 }
358 
359 bool EmptySubobjectMap::CanPlaceBaseAtOffset(const BaseSubobjectInfo *Info,
360  CharUnits Offset) {
361  // If we know this class doesn't have any empty subobjects we don't need to
362  // bother checking.
363  if (SizeOfLargestEmptySubobject.isZero())
364  return true;
365 
366  if (!CanPlaceBaseSubobjectAtOffset(Info, Offset))
367  return false;
368 
369  // We are able to place the base at this offset. Make sure to update the
370  // empty base subobject map.
371  UpdateEmptyBaseSubobjects(Info, Offset, Info->Class->isEmpty());
372  return true;
373 }
374 
375 bool
376 EmptySubobjectMap::CanPlaceFieldSubobjectAtOffset(const CXXRecordDecl *RD,
377  const CXXRecordDecl *Class,
378  CharUnits Offset) const {
379  // We don't have to keep looking past the maximum offset that's known to
380  // contain an empty class.
381  if (!AnyEmptySubobjectsBeyondOffset(Offset))
382  return true;
383 
384  if (!CanPlaceSubobjectAtOffset(RD, Offset))
385  return false;
386 
387  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
388 
389  // Traverse all non-virtual bases.
390  for (const CXXBaseSpecifier &Base : RD->bases()) {
391  if (Base.isVirtual())
392  continue;
393 
394  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
395 
396  CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(BaseDecl);
397  if (!CanPlaceFieldSubobjectAtOffset(BaseDecl, Class, BaseOffset))
398  return false;
399  }
400 
401  if (RD == Class) {
402  // This is the most derived class, traverse virtual bases as well.
403  for (const CXXBaseSpecifier &Base : RD->vbases()) {
404  const CXXRecordDecl *VBaseDecl = Base.getType()->getAsCXXRecordDecl();
405 
406  CharUnits VBaseOffset = Offset + Layout.getVBaseClassOffset(VBaseDecl);
407  if (!CanPlaceFieldSubobjectAtOffset(VBaseDecl, Class, VBaseOffset))
408  return false;
409  }
410  }
411 
412  // Traverse all member variables.
413  unsigned FieldNo = 0;
414  for (CXXRecordDecl::field_iterator I = RD->field_begin(), E = RD->field_end();
415  I != E; ++I, ++FieldNo) {
416  if (I->isBitField())
417  continue;
418 
419  CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
420 
421  if (!CanPlaceFieldSubobjectAtOffset(*I, FieldOffset))
422  return false;
423  }
424 
425  return true;
426 }
427 
428 bool
429 EmptySubobjectMap::CanPlaceFieldSubobjectAtOffset(const FieldDecl *FD,
430  CharUnits Offset) const {
431  // We don't have to keep looking past the maximum offset that's known to
432  // contain an empty class.
433  if (!AnyEmptySubobjectsBeyondOffset(Offset))
434  return true;
435 
436  QualType T = FD->getType();
437  if (const CXXRecordDecl *RD = T->getAsCXXRecordDecl())
438  return CanPlaceFieldSubobjectAtOffset(RD, RD, Offset);
439 
440  // If we have an array type we need to look at every element.
441  if (const ConstantArrayType *AT = Context.getAsConstantArrayType(T)) {
442  QualType ElemTy = Context.getBaseElementType(AT);
443  const RecordType *RT = ElemTy->getAs<RecordType>();
444  if (!RT)
445  return true;
446 
447  const CXXRecordDecl *RD = RT->getAsCXXRecordDecl();
448  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
449 
450  uint64_t NumElements = Context.getConstantArrayElementCount(AT);
451  CharUnits ElementOffset = Offset;
452  for (uint64_t I = 0; I != NumElements; ++I) {
453  // We don't have to keep looking past the maximum offset that's known to
454  // contain an empty class.
455  if (!AnyEmptySubobjectsBeyondOffset(ElementOffset))
456  return true;
457 
458  if (!CanPlaceFieldSubobjectAtOffset(RD, RD, ElementOffset))
459  return false;
460 
461  ElementOffset += Layout.getSize();
462  }
463  }
464 
465  return true;
466 }
467 
468 bool
469 EmptySubobjectMap::CanPlaceFieldAtOffset(const FieldDecl *FD,
470  CharUnits Offset) {
471  if (!CanPlaceFieldSubobjectAtOffset(FD, Offset))
472  return false;
473 
474  // We are able to place the member variable at this offset.
475  // Make sure to update the empty base subobject map.
476  UpdateEmptyFieldSubobjects(FD, Offset);
477  return true;
478 }
479 
480 void EmptySubobjectMap::UpdateEmptyFieldSubobjects(const CXXRecordDecl *RD,
481  const CXXRecordDecl *Class,
482  CharUnits Offset) {
483  // We know that the only empty subobjects that can conflict with empty
484  // field subobjects are subobjects of empty bases that can be placed at offset
485  // zero. Because of this, we only need to keep track of empty field
486  // subobjects with offsets less than the size of the largest empty
487  // subobject for our class.
488  if (Offset >= SizeOfLargestEmptySubobject)
489  return;
490 
491  AddSubobjectAtOffset(RD, Offset);
492 
493  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
494 
495  // Traverse all non-virtual bases.
496  for (const CXXBaseSpecifier &Base : RD->bases()) {
497  if (Base.isVirtual())
498  continue;
499 
500  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
501 
502  CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(BaseDecl);
503  UpdateEmptyFieldSubobjects(BaseDecl, Class, BaseOffset);
504  }
505 
506  if (RD == Class) {
507  // This is the most derived class, traverse virtual bases as well.
508  for (const CXXBaseSpecifier &Base : RD->vbases()) {
509  const CXXRecordDecl *VBaseDecl = Base.getType()->getAsCXXRecordDecl();
510 
511  CharUnits VBaseOffset = Offset + Layout.getVBaseClassOffset(VBaseDecl);
512  UpdateEmptyFieldSubobjects(VBaseDecl, Class, VBaseOffset);
513  }
514  }
515 
516  // Traverse all member variables.
517  unsigned FieldNo = 0;
518  for (CXXRecordDecl::field_iterator I = RD->field_begin(), E = RD->field_end();
519  I != E; ++I, ++FieldNo) {
520  if (I->isBitField())
521  continue;
522 
523  CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
524 
525  UpdateEmptyFieldSubobjects(*I, FieldOffset);
526  }
527 }
528 
529 void EmptySubobjectMap::UpdateEmptyFieldSubobjects(const FieldDecl *FD,
530  CharUnits Offset) {
531  QualType T = FD->getType();
532  if (const CXXRecordDecl *RD = T->getAsCXXRecordDecl()) {
533  UpdateEmptyFieldSubobjects(RD, RD, Offset);
534  return;
535  }
536 
537  // If we have an array type we need to update every element.
538  if (const ConstantArrayType *AT = Context.getAsConstantArrayType(T)) {
539  QualType ElemTy = Context.getBaseElementType(AT);
540  const RecordType *RT = ElemTy->getAs<RecordType>();
541  if (!RT)
542  return;
543 
544  const CXXRecordDecl *RD = RT->getAsCXXRecordDecl();
545  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
546 
547  uint64_t NumElements = Context.getConstantArrayElementCount(AT);
548  CharUnits ElementOffset = Offset;
549 
550  for (uint64_t I = 0; I != NumElements; ++I) {
551  // We know that the only empty subobjects that can conflict with empty
552  // field subobjects are subobjects of empty bases that can be placed at
553  // offset zero. Because of this, we only need to keep track of empty field
554  // subobjects with offsets less than the size of the largest empty
555  // subobject for our class.
556  if (ElementOffset >= SizeOfLargestEmptySubobject)
557  return;
558 
559  UpdateEmptyFieldSubobjects(RD, RD, ElementOffset);
560  ElementOffset += Layout.getSize();
561  }
562  }
563 }
564 
565 typedef llvm::SmallPtrSet<const CXXRecordDecl*, 4> ClassSetTy;
566 
567 class ItaniumRecordLayoutBuilder {
568 protected:
569  // FIXME: Remove this and make the appropriate fields public.
570  friend class clang::ASTContext;
571 
572  const ASTContext &Context;
573 
574  EmptySubobjectMap *EmptySubobjects;
575 
576  /// Size - The current size of the record layout.
577  uint64_t Size;
578 
579  /// Alignment - The current alignment of the record layout.
580  CharUnits Alignment;
581 
582  /// \brief The alignment if attribute packed is not used.
583  CharUnits UnpackedAlignment;
584 
585  SmallVector<uint64_t, 16> FieldOffsets;
586 
587  /// \brief Whether the external AST source has provided a layout for this
588  /// record.
589  unsigned UseExternalLayout : 1;
590 
591  /// \brief Whether we need to infer alignment, even when we have an
592  /// externally-provided layout.
593  unsigned InferAlignment : 1;
594 
595  /// Packed - Whether the record is packed or not.
596  unsigned Packed : 1;
597 
598  unsigned IsUnion : 1;
599 
600  unsigned IsMac68kAlign : 1;
601 
602  unsigned IsMsStruct : 1;
603 
604  /// UnfilledBitsInLastUnit - If the last field laid out was a bitfield,
605  /// this contains the number of bits in the last unit that can be used for
606  /// an adjacent bitfield if necessary. The unit in question is usually
607  /// a byte, but larger units are used if IsMsStruct.
608  unsigned char UnfilledBitsInLastUnit;
609  /// LastBitfieldTypeSize - If IsMsStruct, represents the size of the type
610  /// of the previous field if it was a bitfield.
611  unsigned char LastBitfieldTypeSize;
612 
613  /// MaxFieldAlignment - The maximum allowed field alignment. This is set by
614  /// #pragma pack.
615  CharUnits MaxFieldAlignment;
616 
617  /// DataSize - The data size of the record being laid out.
618  uint64_t DataSize;
619 
620  CharUnits NonVirtualSize;
621  CharUnits NonVirtualAlignment;
622 
623  /// PrimaryBase - the primary base class (if one exists) of the class
624  /// we're laying out.
625  const CXXRecordDecl *PrimaryBase;
626 
627  /// PrimaryBaseIsVirtual - Whether the primary base of the class we're laying
628  /// out is virtual.
629  bool PrimaryBaseIsVirtual;
630 
631  /// HasOwnVFPtr - Whether the class provides its own vtable/vftbl
632  /// pointer, as opposed to inheriting one from a primary base class.
633  bool HasOwnVFPtr;
634 
635  /// \brief the flag of field offset changing due to packed attribute.
636  bool HasPackedField;
637 
638  typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsetsMapTy;
639 
640  /// Bases - base classes and their offsets in the record.
641  BaseOffsetsMapTy Bases;
642 
643  // VBases - virtual base classes and their offsets in the record.
645 
646  /// IndirectPrimaryBases - Virtual base classes, direct or indirect, that are
647  /// primary base classes for some other direct or indirect base class.
648  CXXIndirectPrimaryBaseSet IndirectPrimaryBases;
649 
650  /// FirstNearlyEmptyVBase - The first nearly empty virtual base class in
651  /// inheritance graph order. Used for determining the primary base class.
652  const CXXRecordDecl *FirstNearlyEmptyVBase;
653 
654  /// VisitedVirtualBases - A set of all the visited virtual bases, used to
655  /// avoid visiting virtual bases more than once.
656  llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBases;
657 
658  /// Valid if UseExternalLayout is true.
659  ExternalLayout External;
660 
661  ItaniumRecordLayoutBuilder(const ASTContext &Context,
662  EmptySubobjectMap *EmptySubobjects)
663  : Context(Context), EmptySubobjects(EmptySubobjects), Size(0),
664  Alignment(CharUnits::One()), UnpackedAlignment(CharUnits::One()),
665  UseExternalLayout(false), InferAlignment(false), Packed(false),
666  IsUnion(false), IsMac68kAlign(false), IsMsStruct(false),
667  UnfilledBitsInLastUnit(0), LastBitfieldTypeSize(0),
668  MaxFieldAlignment(CharUnits::Zero()), DataSize(0),
669  NonVirtualSize(CharUnits::Zero()),
670  NonVirtualAlignment(CharUnits::One()), PrimaryBase(nullptr),
671  PrimaryBaseIsVirtual(false), HasOwnVFPtr(false),
672  HasPackedField(false), FirstNearlyEmptyVBase(nullptr) {}
673 
674  void Layout(const RecordDecl *D);
675  void Layout(const CXXRecordDecl *D);
676  void Layout(const ObjCInterfaceDecl *D);
677 
678  void LayoutFields(const RecordDecl *D);
679  void LayoutField(const FieldDecl *D, bool InsertExtraPadding);
680  void LayoutWideBitField(uint64_t FieldSize, uint64_t TypeSize,
681  bool FieldPacked, const FieldDecl *D);
682  void LayoutBitField(const FieldDecl *D);
683 
684  TargetCXXABI getCXXABI() const {
685  return Context.getTargetInfo().getCXXABI();
686  }
687 
688  /// BaseSubobjectInfoAllocator - Allocator for BaseSubobjectInfo objects.
689  llvm::SpecificBumpPtrAllocator<BaseSubobjectInfo> BaseSubobjectInfoAllocator;
690 
691  typedef llvm::DenseMap<const CXXRecordDecl *, BaseSubobjectInfo *>
692  BaseSubobjectInfoMapTy;
693 
694  /// VirtualBaseInfo - Map from all the (direct or indirect) virtual bases
695  /// of the class we're laying out to their base subobject info.
696  BaseSubobjectInfoMapTy VirtualBaseInfo;
697 
698  /// NonVirtualBaseInfo - Map from all the direct non-virtual bases of the
699  /// class we're laying out to their base subobject info.
700  BaseSubobjectInfoMapTy NonVirtualBaseInfo;
701 
702  /// ComputeBaseSubobjectInfo - Compute the base subobject information for the
703  /// bases of the given class.
704  void ComputeBaseSubobjectInfo(const CXXRecordDecl *RD);
705 
706  /// ComputeBaseSubobjectInfo - Compute the base subobject information for a
707  /// single class and all of its base classes.
708  BaseSubobjectInfo *ComputeBaseSubobjectInfo(const CXXRecordDecl *RD,
709  bool IsVirtual,
710  BaseSubobjectInfo *Derived);
711 
712  /// DeterminePrimaryBase - Determine the primary base of the given class.
713  void DeterminePrimaryBase(const CXXRecordDecl *RD);
714 
715  void SelectPrimaryVBase(const CXXRecordDecl *RD);
716 
717  void EnsureVTablePointerAlignment(CharUnits UnpackedBaseAlign);
718 
719  /// LayoutNonVirtualBases - Determines the primary base class (if any) and
720  /// lays it out. Will then proceed to lay out all non-virtual base clasess.
721  void LayoutNonVirtualBases(const CXXRecordDecl *RD);
722 
723  /// LayoutNonVirtualBase - Lays out a single non-virtual base.
724  void LayoutNonVirtualBase(const BaseSubobjectInfo *Base);
725 
726  void AddPrimaryVirtualBaseOffsets(const BaseSubobjectInfo *Info,
727  CharUnits Offset);
728 
729  /// LayoutVirtualBases - Lays out all the virtual bases.
730  void LayoutVirtualBases(const CXXRecordDecl *RD,
731  const CXXRecordDecl *MostDerivedClass);
732 
733  /// LayoutVirtualBase - Lays out a single virtual base.
734  void LayoutVirtualBase(const BaseSubobjectInfo *Base);
735 
736  /// LayoutBase - Will lay out a base and return the offset where it was
737  /// placed, in chars.
738  CharUnits LayoutBase(const BaseSubobjectInfo *Base);
739 
740  /// InitializeLayout - Initialize record layout for the given record decl.
741  void InitializeLayout(const Decl *D);
742 
743  /// FinishLayout - Finalize record layout. Adjust record size based on the
744  /// alignment.
745  void FinishLayout(const NamedDecl *D);
746 
747  void UpdateAlignment(CharUnits NewAlignment, CharUnits UnpackedNewAlignment);
748  void UpdateAlignment(CharUnits NewAlignment) {
749  UpdateAlignment(NewAlignment, NewAlignment);
750  }
751 
752  /// \brief Retrieve the externally-supplied field offset for the given
753  /// field.
754  ///
755  /// \param Field The field whose offset is being queried.
756  /// \param ComputedOffset The offset that we've computed for this field.
757  uint64_t updateExternalFieldOffset(const FieldDecl *Field,
758  uint64_t ComputedOffset);
759 
760  void CheckFieldPadding(uint64_t Offset, uint64_t UnpaddedOffset,
761  uint64_t UnpackedOffset, unsigned UnpackedAlign,
762  bool isPacked, const FieldDecl *D);
763 
764  DiagnosticBuilder Diag(SourceLocation Loc, unsigned DiagID);
765 
766  CharUnits getSize() const {
767  assert(Size % Context.getCharWidth() == 0);
768  return Context.toCharUnitsFromBits(Size);
769  }
770  uint64_t getSizeInBits() const { return Size; }
771 
772  void setSize(CharUnits NewSize) { Size = Context.toBits(NewSize); }
773  void setSize(uint64_t NewSize) { Size = NewSize; }
774 
775  CharUnits getAligment() const { return Alignment; }
776 
777  CharUnits getDataSize() const {
778  assert(DataSize % Context.getCharWidth() == 0);
779  return Context.toCharUnitsFromBits(DataSize);
780  }
781  uint64_t getDataSizeInBits() const { return DataSize; }
782 
783  void setDataSize(CharUnits NewSize) { DataSize = Context.toBits(NewSize); }
784  void setDataSize(uint64_t NewSize) { DataSize = NewSize; }
785 
786  ItaniumRecordLayoutBuilder(const ItaniumRecordLayoutBuilder &) = delete;
787  void operator=(const ItaniumRecordLayoutBuilder &) = delete;
788 };
789 } // end anonymous namespace
790 
791 void ItaniumRecordLayoutBuilder::SelectPrimaryVBase(const CXXRecordDecl *RD) {
792  for (const auto &I : RD->bases()) {
793  assert(!I.getType()->isDependentType() &&
794  "Cannot layout class with dependent bases.");
795 
796  const CXXRecordDecl *Base = I.getType()->getAsCXXRecordDecl();
797 
798  // Check if this is a nearly empty virtual base.
799  if (I.isVirtual() && Context.isNearlyEmpty(Base)) {
800  // If it's not an indirect primary base, then we've found our primary
801  // base.
802  if (!IndirectPrimaryBases.count(Base)) {
803  PrimaryBase = Base;
804  PrimaryBaseIsVirtual = true;
805  return;
806  }
807 
808  // Is this the first nearly empty virtual base?
809  if (!FirstNearlyEmptyVBase)
810  FirstNearlyEmptyVBase = Base;
811  }
812 
813  SelectPrimaryVBase(Base);
814  if (PrimaryBase)
815  return;
816  }
817 }
818 
819 /// DeterminePrimaryBase - Determine the primary base of the given class.
820 void ItaniumRecordLayoutBuilder::DeterminePrimaryBase(const CXXRecordDecl *RD) {
821  // If the class isn't dynamic, it won't have a primary base.
822  if (!RD->isDynamicClass())
823  return;
824 
825  // Compute all the primary virtual bases for all of our direct and
826  // indirect bases, and record all their primary virtual base classes.
827  RD->getIndirectPrimaryBases(IndirectPrimaryBases);
828 
829  // If the record has a dynamic base class, attempt to choose a primary base
830  // class. It is the first (in direct base class order) non-virtual dynamic
831  // base class, if one exists.
832  for (const auto &I : RD->bases()) {
833  // Ignore virtual bases.
834  if (I.isVirtual())
835  continue;
836 
837  const CXXRecordDecl *Base = I.getType()->getAsCXXRecordDecl();
838 
839  if (Base->isDynamicClass()) {
840  // We found it.
841  PrimaryBase = Base;
842  PrimaryBaseIsVirtual = false;
843  return;
844  }
845  }
846 
847  // Under the Itanium ABI, if there is no non-virtual primary base class,
848  // try to compute the primary virtual base. The primary virtual base is
849  // the first nearly empty virtual base that is not an indirect primary
850  // virtual base class, if one exists.
851  if (RD->getNumVBases() != 0) {
852  SelectPrimaryVBase(RD);
853  if (PrimaryBase)
854  return;
855  }
856 
857  // Otherwise, it is the first indirect primary base class, if one exists.
858  if (FirstNearlyEmptyVBase) {
859  PrimaryBase = FirstNearlyEmptyVBase;
860  PrimaryBaseIsVirtual = true;
861  return;
862  }
863 
864  assert(!PrimaryBase && "Should not get here with a primary base!");
865 }
866 
867 BaseSubobjectInfo *ItaniumRecordLayoutBuilder::ComputeBaseSubobjectInfo(
868  const CXXRecordDecl *RD, bool IsVirtual, BaseSubobjectInfo *Derived) {
869  BaseSubobjectInfo *Info;
870 
871  if (IsVirtual) {
872  // Check if we already have info about this virtual base.
873  BaseSubobjectInfo *&InfoSlot = VirtualBaseInfo[RD];
874  if (InfoSlot) {
875  assert(InfoSlot->Class == RD && "Wrong class for virtual base info!");
876  return InfoSlot;
877  }
878 
879  // We don't, create it.
880  InfoSlot = new (BaseSubobjectInfoAllocator.Allocate()) BaseSubobjectInfo;
881  Info = InfoSlot;
882  } else {
883  Info = new (BaseSubobjectInfoAllocator.Allocate()) BaseSubobjectInfo;
884  }
885 
886  Info->Class = RD;
887  Info->IsVirtual = IsVirtual;
888  Info->Derived = nullptr;
889  Info->PrimaryVirtualBaseInfo = nullptr;
890 
891  const CXXRecordDecl *PrimaryVirtualBase = nullptr;
892  BaseSubobjectInfo *PrimaryVirtualBaseInfo = nullptr;
893 
894  // Check if this base has a primary virtual base.
895  if (RD->getNumVBases()) {
896  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
897  if (Layout.isPrimaryBaseVirtual()) {
898  // This base does have a primary virtual base.
899  PrimaryVirtualBase = Layout.getPrimaryBase();
900  assert(PrimaryVirtualBase && "Didn't have a primary virtual base!");
901 
902  // Now check if we have base subobject info about this primary base.
903  PrimaryVirtualBaseInfo = VirtualBaseInfo.lookup(PrimaryVirtualBase);
904 
905  if (PrimaryVirtualBaseInfo) {
906  if (PrimaryVirtualBaseInfo->Derived) {
907  // We did have info about this primary base, and it turns out that it
908  // has already been claimed as a primary virtual base for another
909  // base.
910  PrimaryVirtualBase = nullptr;
911  } else {
912  // We can claim this base as our primary base.
913  Info->PrimaryVirtualBaseInfo = PrimaryVirtualBaseInfo;
914  PrimaryVirtualBaseInfo->Derived = Info;
915  }
916  }
917  }
918  }
919 
920  // Now go through all direct bases.
921  for (const auto &I : RD->bases()) {
922  bool IsVirtual = I.isVirtual();
923 
924  const CXXRecordDecl *BaseDecl = I.getType()->getAsCXXRecordDecl();
925 
926  Info->Bases.push_back(ComputeBaseSubobjectInfo(BaseDecl, IsVirtual, Info));
927  }
928 
929  if (PrimaryVirtualBase && !PrimaryVirtualBaseInfo) {
930  // Traversing the bases must have created the base info for our primary
931  // virtual base.
932  PrimaryVirtualBaseInfo = VirtualBaseInfo.lookup(PrimaryVirtualBase);
933  assert(PrimaryVirtualBaseInfo &&
934  "Did not create a primary virtual base!");
935 
936  // Claim the primary virtual base as our primary virtual base.
937  Info->PrimaryVirtualBaseInfo = PrimaryVirtualBaseInfo;
938  PrimaryVirtualBaseInfo->Derived = Info;
939  }
940 
941  return Info;
942 }
943 
944 void ItaniumRecordLayoutBuilder::ComputeBaseSubobjectInfo(
945  const CXXRecordDecl *RD) {
946  for (const auto &I : RD->bases()) {
947  bool IsVirtual = I.isVirtual();
948 
949  const CXXRecordDecl *BaseDecl = I.getType()->getAsCXXRecordDecl();
950 
951  // Compute the base subobject info for this base.
952  BaseSubobjectInfo *Info = ComputeBaseSubobjectInfo(BaseDecl, IsVirtual,
953  nullptr);
954 
955  if (IsVirtual) {
956  // ComputeBaseInfo has already added this base for us.
957  assert(VirtualBaseInfo.count(BaseDecl) &&
958  "Did not add virtual base!");
959  } else {
960  // Add the base info to the map of non-virtual bases.
961  assert(!NonVirtualBaseInfo.count(BaseDecl) &&
962  "Non-virtual base already exists!");
963  NonVirtualBaseInfo.insert(std::make_pair(BaseDecl, Info));
964  }
965  }
966 }
967 
968 void ItaniumRecordLayoutBuilder::EnsureVTablePointerAlignment(
969  CharUnits UnpackedBaseAlign) {
970  CharUnits BaseAlign = (Packed) ? CharUnits::One() : UnpackedBaseAlign;
971 
972  // The maximum field alignment overrides base align.
973  if (!MaxFieldAlignment.isZero()) {
974  BaseAlign = std::min(BaseAlign, MaxFieldAlignment);
975  UnpackedBaseAlign = std::min(UnpackedBaseAlign, MaxFieldAlignment);
976  }
977 
978  // Round up the current record size to pointer alignment.
979  setSize(getSize().alignTo(BaseAlign));
980  setDataSize(getSize());
981 
982  // Update the alignment.
983  UpdateAlignment(BaseAlign, UnpackedBaseAlign);
984 }
985 
986 void ItaniumRecordLayoutBuilder::LayoutNonVirtualBases(
987  const CXXRecordDecl *RD) {
988  // Then, determine the primary base class.
989  DeterminePrimaryBase(RD);
990 
991  // Compute base subobject info.
992  ComputeBaseSubobjectInfo(RD);
993 
994  // If we have a primary base class, lay it out.
995  if (PrimaryBase) {
996  if (PrimaryBaseIsVirtual) {
997  // If the primary virtual base was a primary virtual base of some other
998  // base class we'll have to steal it.
999  BaseSubobjectInfo *PrimaryBaseInfo = VirtualBaseInfo.lookup(PrimaryBase);
1000  PrimaryBaseInfo->Derived = nullptr;
1001 
1002  // We have a virtual primary base, insert it as an indirect primary base.
1003  IndirectPrimaryBases.insert(PrimaryBase);
1004 
1005  assert(!VisitedVirtualBases.count(PrimaryBase) &&
1006  "vbase already visited!");
1007  VisitedVirtualBases.insert(PrimaryBase);
1008 
1009  LayoutVirtualBase(PrimaryBaseInfo);
1010  } else {
1011  BaseSubobjectInfo *PrimaryBaseInfo =
1012  NonVirtualBaseInfo.lookup(PrimaryBase);
1013  assert(PrimaryBaseInfo &&
1014  "Did not find base info for non-virtual primary base!");
1015 
1016  LayoutNonVirtualBase(PrimaryBaseInfo);
1017  }
1018 
1019  // If this class needs a vtable/vf-table and didn't get one from a
1020  // primary base, add it in now.
1021  } else if (RD->isDynamicClass()) {
1022  assert(DataSize == 0 && "Vtable pointer must be at offset zero!");
1023  CharUnits PtrWidth =
1024  Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
1025  CharUnits PtrAlign =
1026  Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerAlign(0));
1027  EnsureVTablePointerAlignment(PtrAlign);
1028  HasOwnVFPtr = true;
1029  setSize(getSize() + PtrWidth);
1030  setDataSize(getSize());
1031  }
1032 
1033  // Now lay out the non-virtual bases.
1034  for (const auto &I : RD->bases()) {
1035 
1036  // Ignore virtual bases.
1037  if (I.isVirtual())
1038  continue;
1039 
1040  const CXXRecordDecl *BaseDecl = I.getType()->getAsCXXRecordDecl();
1041 
1042  // Skip the primary base, because we've already laid it out. The
1043  // !PrimaryBaseIsVirtual check is required because we might have a
1044  // non-virtual base of the same type as a primary virtual base.
1045  if (BaseDecl == PrimaryBase && !PrimaryBaseIsVirtual)
1046  continue;
1047 
1048  // Lay out the base.
1049  BaseSubobjectInfo *BaseInfo = NonVirtualBaseInfo.lookup(BaseDecl);
1050  assert(BaseInfo && "Did not find base info for non-virtual base!");
1051 
1052  LayoutNonVirtualBase(BaseInfo);
1053  }
1054 }
1055 
1056 void ItaniumRecordLayoutBuilder::LayoutNonVirtualBase(
1057  const BaseSubobjectInfo *Base) {
1058  // Layout the base.
1059  CharUnits Offset = LayoutBase(Base);
1060 
1061  // Add its base class offset.
1062  assert(!Bases.count(Base->Class) && "base offset already exists!");
1063  Bases.insert(std::make_pair(Base->Class, Offset));
1064 
1065  AddPrimaryVirtualBaseOffsets(Base, Offset);
1066 }
1067 
1068 void ItaniumRecordLayoutBuilder::AddPrimaryVirtualBaseOffsets(
1069  const BaseSubobjectInfo *Info, CharUnits Offset) {
1070  // This base isn't interesting, it has no virtual bases.
1071  if (!Info->Class->getNumVBases())
1072  return;
1073 
1074  // First, check if we have a virtual primary base to add offsets for.
1075  if (Info->PrimaryVirtualBaseInfo) {
1076  assert(Info->PrimaryVirtualBaseInfo->IsVirtual &&
1077  "Primary virtual base is not virtual!");
1078  if (Info->PrimaryVirtualBaseInfo->Derived == Info) {
1079  // Add the offset.
1080  assert(!VBases.count(Info->PrimaryVirtualBaseInfo->Class) &&
1081  "primary vbase offset already exists!");
1082  VBases.insert(std::make_pair(Info->PrimaryVirtualBaseInfo->Class,
1083  ASTRecordLayout::VBaseInfo(Offset, false)));
1084 
1085  // Traverse the primary virtual base.
1086  AddPrimaryVirtualBaseOffsets(Info->PrimaryVirtualBaseInfo, Offset);
1087  }
1088  }
1089 
1090  // Now go through all direct non-virtual bases.
1091  const ASTRecordLayout &Layout = Context.getASTRecordLayout(Info->Class);
1092  for (const BaseSubobjectInfo *Base : Info->Bases) {
1093  if (Base->IsVirtual)
1094  continue;
1095 
1096  CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base->Class);
1097  AddPrimaryVirtualBaseOffsets(Base, BaseOffset);
1098  }
1099 }
1100 
1101 void ItaniumRecordLayoutBuilder::LayoutVirtualBases(
1102  const CXXRecordDecl *RD, const CXXRecordDecl *MostDerivedClass) {
1103  const CXXRecordDecl *PrimaryBase;
1104  bool PrimaryBaseIsVirtual;
1105 
1106  if (MostDerivedClass == RD) {
1107  PrimaryBase = this->PrimaryBase;
1108  PrimaryBaseIsVirtual = this->PrimaryBaseIsVirtual;
1109  } else {
1110  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1111  PrimaryBase = Layout.getPrimaryBase();
1112  PrimaryBaseIsVirtual = Layout.isPrimaryBaseVirtual();
1113  }
1114 
1115  for (const CXXBaseSpecifier &Base : RD->bases()) {
1116  assert(!Base.getType()->isDependentType() &&
1117  "Cannot layout class with dependent bases.");
1118 
1119  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
1120 
1121  if (Base.isVirtual()) {
1122  if (PrimaryBase != BaseDecl || !PrimaryBaseIsVirtual) {
1123  bool IndirectPrimaryBase = IndirectPrimaryBases.count(BaseDecl);
1124 
1125  // Only lay out the virtual base if it's not an indirect primary base.
1126  if (!IndirectPrimaryBase) {
1127  // Only visit virtual bases once.
1128  if (!VisitedVirtualBases.insert(BaseDecl).second)
1129  continue;
1130 
1131  const BaseSubobjectInfo *BaseInfo = VirtualBaseInfo.lookup(BaseDecl);
1132  assert(BaseInfo && "Did not find virtual base info!");
1133  LayoutVirtualBase(BaseInfo);
1134  }
1135  }
1136  }
1137 
1138  if (!BaseDecl->getNumVBases()) {
1139  // This base isn't interesting since it doesn't have any virtual bases.
1140  continue;
1141  }
1142 
1143  LayoutVirtualBases(BaseDecl, MostDerivedClass);
1144  }
1145 }
1146 
1147 void ItaniumRecordLayoutBuilder::LayoutVirtualBase(
1148  const BaseSubobjectInfo *Base) {
1149  assert(!Base->Derived && "Trying to lay out a primary virtual base!");
1150 
1151  // Layout the base.
1152  CharUnits Offset = LayoutBase(Base);
1153 
1154  // Add its base class offset.
1155  assert(!VBases.count(Base->Class) && "vbase offset already exists!");
1156  VBases.insert(std::make_pair(Base->Class,
1157  ASTRecordLayout::VBaseInfo(Offset, false)));
1158 
1159  AddPrimaryVirtualBaseOffsets(Base, Offset);
1160 }
1161 
1162 CharUnits
1163 ItaniumRecordLayoutBuilder::LayoutBase(const BaseSubobjectInfo *Base) {
1164  const ASTRecordLayout &Layout = Context.getASTRecordLayout(Base->Class);
1165 
1166 
1167  CharUnits Offset;
1168 
1169  // Query the external layout to see if it provides an offset.
1170  bool HasExternalLayout = false;
1171  if (UseExternalLayout) {
1172  if (Base->IsVirtual)
1173  HasExternalLayout = External.getExternalNVBaseOffset(Base->Class, Offset);
1174  else
1175  HasExternalLayout = External.getExternalVBaseOffset(Base->Class, Offset);
1176  }
1177 
1178  CharUnits UnpackedBaseAlign = Layout.getNonVirtualAlignment();
1179  CharUnits BaseAlign = (Packed) ? CharUnits::One() : UnpackedBaseAlign;
1180 
1181  // If we have an empty base class, try to place it at offset 0.
1182  if (Base->Class->isEmpty() &&
1183  (!HasExternalLayout || Offset == CharUnits::Zero()) &&
1184  EmptySubobjects->CanPlaceBaseAtOffset(Base, CharUnits::Zero())) {
1185  setSize(std::max(getSize(), Layout.getSize()));
1186  UpdateAlignment(BaseAlign, UnpackedBaseAlign);
1187 
1188  return CharUnits::Zero();
1189  }
1190 
1191  // The maximum field alignment overrides base align.
1192  if (!MaxFieldAlignment.isZero()) {
1193  BaseAlign = std::min(BaseAlign, MaxFieldAlignment);
1194  UnpackedBaseAlign = std::min(UnpackedBaseAlign, MaxFieldAlignment);
1195  }
1196 
1197  if (!HasExternalLayout) {
1198  // Round up the current record size to the base's alignment boundary.
1199  Offset = getDataSize().alignTo(BaseAlign);
1200 
1201  // Try to place the base.
1202  while (!EmptySubobjects->CanPlaceBaseAtOffset(Base, Offset))
1203  Offset += BaseAlign;
1204  } else {
1205  bool Allowed = EmptySubobjects->CanPlaceBaseAtOffset(Base, Offset);
1206  (void)Allowed;
1207  assert(Allowed && "Base subobject externally placed at overlapping offset");
1208 
1209  if (InferAlignment && Offset < getDataSize().alignTo(BaseAlign)) {
1210  // The externally-supplied base offset is before the base offset we
1211  // computed. Assume that the structure is packed.
1212  Alignment = CharUnits::One();
1213  InferAlignment = false;
1214  }
1215  }
1216 
1217  if (!Base->Class->isEmpty()) {
1218  // Update the data size.
1219  setDataSize(Offset + Layout.getNonVirtualSize());
1220 
1221  setSize(std::max(getSize(), getDataSize()));
1222  } else
1223  setSize(std::max(getSize(), Offset + Layout.getSize()));
1224 
1225  // Remember max struct/class alignment.
1226  UpdateAlignment(BaseAlign, UnpackedBaseAlign);
1227 
1228  return Offset;
1229 }
1230 
1231 void ItaniumRecordLayoutBuilder::InitializeLayout(const Decl *D) {
1232  if (const RecordDecl *RD = dyn_cast<RecordDecl>(D)) {
1233  IsUnion = RD->isUnion();
1234  IsMsStruct = RD->isMsStruct(Context);
1235  }
1236 
1237  Packed = D->hasAttr<PackedAttr>();
1238 
1239  // Honor the default struct packing maximum alignment flag.
1240  if (unsigned DefaultMaxFieldAlignment = Context.getLangOpts().PackStruct) {
1241  MaxFieldAlignment = CharUnits::fromQuantity(DefaultMaxFieldAlignment);
1242  }
1243 
1244  // mac68k alignment supersedes maximum field alignment and attribute aligned,
1245  // and forces all structures to have 2-byte alignment. The IBM docs on it
1246  // allude to additional (more complicated) semantics, especially with regard
1247  // to bit-fields, but gcc appears not to follow that.
1248  if (D->hasAttr<AlignMac68kAttr>()) {
1249  IsMac68kAlign = true;
1250  MaxFieldAlignment = CharUnits::fromQuantity(2);
1251  Alignment = CharUnits::fromQuantity(2);
1252  } else {
1253  if (const MaxFieldAlignmentAttr *MFAA = D->getAttr<MaxFieldAlignmentAttr>())
1254  MaxFieldAlignment = Context.toCharUnitsFromBits(MFAA->getAlignment());
1255 
1256  if (unsigned MaxAlign = D->getMaxAlignment())
1257  UpdateAlignment(Context.toCharUnitsFromBits(MaxAlign));
1258  }
1259 
1260  // If there is an external AST source, ask it for the various offsets.
1261  if (const RecordDecl *RD = dyn_cast<RecordDecl>(D))
1262  if (ExternalASTSource *Source = Context.getExternalSource()) {
1263  UseExternalLayout = Source->layoutRecordType(
1264  RD, External.Size, External.Align, External.FieldOffsets,
1265  External.BaseOffsets, External.VirtualBaseOffsets);
1266 
1267  // Update based on external alignment.
1268  if (UseExternalLayout) {
1269  if (External.Align > 0) {
1270  Alignment = Context.toCharUnitsFromBits(External.Align);
1271  } else {
1272  // The external source didn't have alignment information; infer it.
1273  InferAlignment = true;
1274  }
1275  }
1276  }
1277 }
1278 
1279 void ItaniumRecordLayoutBuilder::Layout(const RecordDecl *D) {
1280  InitializeLayout(D);
1281  LayoutFields(D);
1282 
1283  // Finally, round the size of the total struct up to the alignment of the
1284  // struct itself.
1285  FinishLayout(D);
1286 }
1287 
1288 void ItaniumRecordLayoutBuilder::Layout(const CXXRecordDecl *RD) {
1289  InitializeLayout(RD);
1290 
1291  // Lay out the vtable and the non-virtual bases.
1292  LayoutNonVirtualBases(RD);
1293 
1294  LayoutFields(RD);
1295 
1296  NonVirtualSize = Context.toCharUnitsFromBits(
1297  llvm::alignTo(getSizeInBits(), Context.getTargetInfo().getCharAlign()));
1298  NonVirtualAlignment = Alignment;
1299 
1300  // Lay out the virtual bases and add the primary virtual base offsets.
1301  LayoutVirtualBases(RD, RD);
1302 
1303  // Finally, round the size of the total struct up to the alignment
1304  // of the struct itself.
1305  FinishLayout(RD);
1306 
1307 #ifndef NDEBUG
1308  // Check that we have base offsets for all bases.
1309  for (const CXXBaseSpecifier &Base : RD->bases()) {
1310  if (Base.isVirtual())
1311  continue;
1312 
1313  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
1314 
1315  assert(Bases.count(BaseDecl) && "Did not find base offset!");
1316  }
1317 
1318  // And all virtual bases.
1319  for (const CXXBaseSpecifier &Base : RD->vbases()) {
1320  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
1321 
1322  assert(VBases.count(BaseDecl) && "Did not find base offset!");
1323  }
1324 #endif
1325 }
1326 
1327 void ItaniumRecordLayoutBuilder::Layout(const ObjCInterfaceDecl *D) {
1328  if (ObjCInterfaceDecl *SD = D->getSuperClass()) {
1329  const ASTRecordLayout &SL = Context.getASTObjCInterfaceLayout(SD);
1330 
1331  UpdateAlignment(SL.getAlignment());
1332 
1333  // We start laying out ivars not at the end of the superclass
1334  // structure, but at the next byte following the last field.
1335  setSize(SL.getDataSize());
1336  setDataSize(getSize());
1337  }
1338 
1339  InitializeLayout(D);
1340  // Layout each ivar sequentially.
1341  for (const ObjCIvarDecl *IVD = D->all_declared_ivar_begin(); IVD;
1342  IVD = IVD->getNextIvar())
1343  LayoutField(IVD, false);
1344 
1345  // Finally, round the size of the total struct up to the alignment of the
1346  // struct itself.
1347  FinishLayout(D);
1348 }
1349 
1350 void ItaniumRecordLayoutBuilder::LayoutFields(const RecordDecl *D) {
1351  // Layout each field, for now, just sequentially, respecting alignment. In
1352  // the future, this will need to be tweakable by targets.
1353  bool InsertExtraPadding = D->mayInsertExtraPadding(/*EmitRemark=*/true);
1354  bool HasFlexibleArrayMember = D->hasFlexibleArrayMember();
1355  for (auto I = D->field_begin(), End = D->field_end(); I != End; ++I) {
1356  auto Next(I);
1357  ++Next;
1358  LayoutField(*I,
1359  InsertExtraPadding && (Next != End || !HasFlexibleArrayMember));
1360  }
1361 }
1362 
1363 // Rounds the specified size to have it a multiple of the char size.
1364 static uint64_t
1366  const ASTContext &Context) {
1367  uint64_t CharAlignment = Context.getTargetInfo().getCharAlign();
1368  return llvm::alignTo(Size, CharAlignment);
1369 }
1370 
1371 void ItaniumRecordLayoutBuilder::LayoutWideBitField(uint64_t FieldSize,
1372  uint64_t TypeSize,
1373  bool FieldPacked,
1374  const FieldDecl *D) {
1375  assert(Context.getLangOpts().CPlusPlus &&
1376  "Can only have wide bit-fields in C++!");
1377 
1378  // Itanium C++ ABI 2.4:
1379  // If sizeof(T)*8 < n, let T' be the largest integral POD type with
1380  // sizeof(T')*8 <= n.
1381 
1382  QualType IntegralPODTypes[] = {
1383  Context.UnsignedCharTy, Context.UnsignedShortTy, Context.UnsignedIntTy,
1384  Context.UnsignedLongTy, Context.UnsignedLongLongTy
1385  };
1386 
1387  QualType Type;
1388  for (const QualType &QT : IntegralPODTypes) {
1389  uint64_t Size = Context.getTypeSize(QT);
1390 
1391  if (Size > FieldSize)
1392  break;
1393 
1394  Type = QT;
1395  }
1396  assert(!Type.isNull() && "Did not find a type!");
1397 
1398  CharUnits TypeAlign = Context.getTypeAlignInChars(Type);
1399 
1400  // We're not going to use any of the unfilled bits in the last byte.
1401  UnfilledBitsInLastUnit = 0;
1402  LastBitfieldTypeSize = 0;
1403 
1404  uint64_t FieldOffset;
1405  uint64_t UnpaddedFieldOffset = getDataSizeInBits() - UnfilledBitsInLastUnit;
1406 
1407  if (IsUnion) {
1408  uint64_t RoundedFieldSize = roundUpSizeToCharAlignment(FieldSize,
1409  Context);
1410  setDataSize(std::max(getDataSizeInBits(), RoundedFieldSize));
1411  FieldOffset = 0;
1412  } else {
1413  // The bitfield is allocated starting at the next offset aligned
1414  // appropriately for T', with length n bits.
1415  FieldOffset = llvm::alignTo(getDataSizeInBits(), Context.toBits(TypeAlign));
1416 
1417  uint64_t NewSizeInBits = FieldOffset + FieldSize;
1418 
1419  setDataSize(
1420  llvm::alignTo(NewSizeInBits, Context.getTargetInfo().getCharAlign()));
1421  UnfilledBitsInLastUnit = getDataSizeInBits() - NewSizeInBits;
1422  }
1423 
1424  // Place this field at the current location.
1425  FieldOffsets.push_back(FieldOffset);
1426 
1427  CheckFieldPadding(FieldOffset, UnpaddedFieldOffset, FieldOffset,
1428  Context.toBits(TypeAlign), FieldPacked, D);
1429 
1430  // Update the size.
1431  setSize(std::max(getSizeInBits(), getDataSizeInBits()));
1432 
1433  // Remember max struct/class alignment.
1434  UpdateAlignment(TypeAlign);
1435 }
1436 
1437 void ItaniumRecordLayoutBuilder::LayoutBitField(const FieldDecl *D) {
1438  bool FieldPacked = Packed || D->hasAttr<PackedAttr>();
1439  uint64_t FieldSize = D->getBitWidthValue(Context);
1440  TypeInfo FieldInfo = Context.getTypeInfo(D->getType());
1441  uint64_t TypeSize = FieldInfo.Width;
1442  unsigned FieldAlign = FieldInfo.Align;
1443 
1444  // UnfilledBitsInLastUnit is the difference between the end of the
1445  // last allocated bitfield (i.e. the first bit offset available for
1446  // bitfields) and the end of the current data size in bits (i.e. the
1447  // first bit offset available for non-bitfields). The current data
1448  // size in bits is always a multiple of the char size; additionally,
1449  // for ms_struct records it's also a multiple of the
1450  // LastBitfieldTypeSize (if set).
1451 
1452  // The struct-layout algorithm is dictated by the platform ABI,
1453  // which in principle could use almost any rules it likes. In
1454  // practice, UNIXy targets tend to inherit the algorithm described
1455  // in the System V generic ABI. The basic bitfield layout rule in
1456  // System V is to place bitfields at the next available bit offset
1457  // where the entire bitfield would fit in an aligned storage unit of
1458  // the declared type; it's okay if an earlier or later non-bitfield
1459  // is allocated in the same storage unit. However, some targets
1460  // (those that !useBitFieldTypeAlignment(), e.g. ARM APCS) don't
1461  // require this storage unit to be aligned, and therefore always put
1462  // the bitfield at the next available bit offset.
1463 
1464  // ms_struct basically requests a complete replacement of the
1465  // platform ABI's struct-layout algorithm, with the high-level goal
1466  // of duplicating MSVC's layout. For non-bitfields, this follows
1467  // the standard algorithm. The basic bitfield layout rule is to
1468  // allocate an entire unit of the bitfield's declared type
1469  // (e.g. 'unsigned long'), then parcel it up among successive
1470  // bitfields whose declared types have the same size, making a new
1471  // unit as soon as the last can no longer store the whole value.
1472  // Since it completely replaces the platform ABI's algorithm,
1473  // settings like !useBitFieldTypeAlignment() do not apply.
1474 
1475  // A zero-width bitfield forces the use of a new storage unit for
1476  // later bitfields. In general, this occurs by rounding up the
1477  // current size of the struct as if the algorithm were about to
1478  // place a non-bitfield of the field's formal type. Usually this
1479  // does not change the alignment of the struct itself, but it does
1480  // on some targets (those that useZeroLengthBitfieldAlignment(),
1481  // e.g. ARM). In ms_struct layout, zero-width bitfields are
1482  // ignored unless they follow a non-zero-width bitfield.
1483 
1484  // A field alignment restriction (e.g. from #pragma pack) or
1485  // specification (e.g. from __attribute__((aligned))) changes the
1486  // formal alignment of the field. For System V, this alters the
1487  // required alignment of the notional storage unit that must contain
1488  // the bitfield. For ms_struct, this only affects the placement of
1489  // new storage units. In both cases, the effect of #pragma pack is
1490  // ignored on zero-width bitfields.
1491 
1492  // On System V, a packed field (e.g. from #pragma pack or
1493  // __attribute__((packed))) always uses the next available bit
1494  // offset.
1495 
1496  // In an ms_struct struct, the alignment of a fundamental type is
1497  // always equal to its size. This is necessary in order to mimic
1498  // the i386 alignment rules on targets which might not fully align
1499  // all types (e.g. Darwin PPC32, where alignof(long long) == 4).
1500 
1501  // First, some simple bookkeeping to perform for ms_struct structs.
1502  if (IsMsStruct) {
1503  // The field alignment for integer types is always the size.
1504  FieldAlign = TypeSize;
1505 
1506  // If the previous field was not a bitfield, or was a bitfield
1507  // with a different storage unit size, or if this field doesn't fit into
1508  // the current storage unit, we're done with that storage unit.
1509  if (LastBitfieldTypeSize != TypeSize ||
1510  UnfilledBitsInLastUnit < FieldSize) {
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 = Context.getTargetAddressSpace(RT->getPointeeType());
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 
1756  if (!llvm::isPowerOf2_64(TypeSize.getQuantity())) {
1757  assert(
1758  !Context.getTargetInfo().getTriple().isWindowsMSVCEnvironment() &&
1759  "Non PowerOf2 size in MSVC mode");
1760  // Base types with sizes that aren't a power of two don't work
1761  // with the layout rules for MS structs. This isn't an issue in
1762  // MSVC itself since there are no such base data types there.
1763  // On e.g. x86_32 mingw and linux, long double is 12 bytes though.
1764  // Any structs involving that data type obviously can't be ABI
1765  // compatible with MSVC regardless of how it is laid out.
1766 
1767  // Since ms_struct can be mass enabled (via a pragma or via the
1768  // -mms-bitfields command line parameter), this can trigger for
1769  // structs that don't actually need MSVC compatibility, so we
1770  // need to be able to sidestep the ms_struct layout for these types.
1771 
1772  // Since the combination of -mms-bitfields together with structs
1773  // like max_align_t (which contains a long double) for mingw is
1774  // quite comon (and GCC handles it silently), just handle it
1775  // silently there. For other targets that have ms_struct enabled
1776  // (most probably via a pragma or attribute), trigger a diagnostic
1777  // that defaults to an error.
1778  if (!Context.getTargetInfo().getTriple().isWindowsGNUEnvironment())
1779  Diag(D->getLocation(), diag::warn_npot_ms_struct);
1780  }
1781  if (TypeSize > FieldAlign &&
1782  llvm::isPowerOf2_64(TypeSize.getQuantity()))
1783  FieldAlign = TypeSize;
1784  }
1785  }
1786  }
1787 
1788  // The align if the field is not packed. This is to check if the attribute
1789  // was unnecessary (-Wpacked).
1790  CharUnits UnpackedFieldAlign = FieldAlign;
1791  CharUnits UnpackedFieldOffset = FieldOffset;
1792 
1793  if (FieldPacked)
1794  FieldAlign = CharUnits::One();
1795  CharUnits MaxAlignmentInChars =
1796  Context.toCharUnitsFromBits(D->getMaxAlignment());
1797  FieldAlign = std::max(FieldAlign, MaxAlignmentInChars);
1798  UnpackedFieldAlign = std::max(UnpackedFieldAlign, MaxAlignmentInChars);
1799 
1800  // The maximum field alignment overrides the aligned attribute.
1801  if (!MaxFieldAlignment.isZero()) {
1802  FieldAlign = std::min(FieldAlign, MaxFieldAlignment);
1803  UnpackedFieldAlign = std::min(UnpackedFieldAlign, MaxFieldAlignment);
1804  }
1805 
1806  // Round up the current record size to the field's alignment boundary.
1807  FieldOffset = FieldOffset.alignTo(FieldAlign);
1808  UnpackedFieldOffset = UnpackedFieldOffset.alignTo(UnpackedFieldAlign);
1809 
1810  if (UseExternalLayout) {
1811  FieldOffset = Context.toCharUnitsFromBits(
1812  updateExternalFieldOffset(D, Context.toBits(FieldOffset)));
1813 
1814  if (!IsUnion && EmptySubobjects) {
1815  // Record the fact that we're placing a field at this offset.
1816  bool Allowed = EmptySubobjects->CanPlaceFieldAtOffset(D, FieldOffset);
1817  (void)Allowed;
1818  assert(Allowed && "Externally-placed field cannot be placed here");
1819  }
1820  } else {
1821  if (!IsUnion && EmptySubobjects) {
1822  // Check if we can place the field at this offset.
1823  while (!EmptySubobjects->CanPlaceFieldAtOffset(D, FieldOffset)) {
1824  // We couldn't place the field at the offset. Try again at a new offset.
1825  FieldOffset += FieldAlign;
1826  }
1827  }
1828  }
1829 
1830  // Place this field at the current location.
1831  FieldOffsets.push_back(Context.toBits(FieldOffset));
1832 
1833  if (!UseExternalLayout)
1834  CheckFieldPadding(Context.toBits(FieldOffset), UnpaddedFieldOffset,
1835  Context.toBits(UnpackedFieldOffset),
1836  Context.toBits(UnpackedFieldAlign), FieldPacked, D);
1837 
1838  if (InsertExtraPadding) {
1839  CharUnits ASanAlignment = CharUnits::fromQuantity(8);
1840  CharUnits ExtraSizeForAsan = ASanAlignment;
1841  if (FieldSize % ASanAlignment)
1842  ExtraSizeForAsan +=
1843  ASanAlignment - CharUnits::fromQuantity(FieldSize % ASanAlignment);
1844  FieldSize += ExtraSizeForAsan;
1845  }
1846 
1847  // Reserve space for this field.
1848  uint64_t FieldSizeInBits = Context.toBits(FieldSize);
1849  if (IsUnion)
1850  setDataSize(std::max(getDataSizeInBits(), FieldSizeInBits));
1851  else
1852  setDataSize(FieldOffset + FieldSize);
1853 
1854  // Update the size.
1855  setSize(std::max(getSizeInBits(), getDataSizeInBits()));
1856 
1857  // Remember max struct/class alignment.
1858  UpdateAlignment(FieldAlign, UnpackedFieldAlign);
1859 }
1860 
1861 void ItaniumRecordLayoutBuilder::FinishLayout(const NamedDecl *D) {
1862  // In C++, records cannot be of size 0.
1863  if (Context.getLangOpts().CPlusPlus && getSizeInBits() == 0) {
1864  if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D)) {
1865  // Compatibility with gcc requires a class (pod or non-pod)
1866  // which is not empty but of size 0; such as having fields of
1867  // array of zero-length, remains of Size 0
1868  if (RD->isEmpty())
1869  setSize(CharUnits::One());
1870  }
1871  else
1872  setSize(CharUnits::One());
1873  }
1874 
1875  // Finally, round the size of the record up to the alignment of the
1876  // record itself.
1877  uint64_t UnpaddedSize = getSizeInBits() - UnfilledBitsInLastUnit;
1878  uint64_t UnpackedSizeInBits =
1879  llvm::alignTo(getSizeInBits(), Context.toBits(UnpackedAlignment));
1880  uint64_t RoundedSize =
1881  llvm::alignTo(getSizeInBits(), Context.toBits(Alignment));
1882 
1883  if (UseExternalLayout) {
1884  // If we're inferring alignment, and the external size is smaller than
1885  // our size after we've rounded up to alignment, conservatively set the
1886  // alignment to 1.
1887  if (InferAlignment && External.Size < RoundedSize) {
1888  Alignment = CharUnits::One();
1889  InferAlignment = false;
1890  }
1891  setSize(External.Size);
1892  return;
1893  }
1894 
1895  // Set the size to the final size.
1896  setSize(RoundedSize);
1897 
1898  unsigned CharBitNum = Context.getTargetInfo().getCharWidth();
1899  if (const RecordDecl *RD = dyn_cast<RecordDecl>(D)) {
1900  // Warn if padding was introduced to the struct/class/union.
1901  if (getSizeInBits() > UnpaddedSize) {
1902  unsigned PadSize = getSizeInBits() - UnpaddedSize;
1903  bool InBits = true;
1904  if (PadSize % CharBitNum == 0) {
1905  PadSize = PadSize / CharBitNum;
1906  InBits = false;
1907  }
1908  Diag(RD->getLocation(), diag::warn_padded_struct_size)
1909  << Context.getTypeDeclType(RD)
1910  << PadSize
1911  << (InBits ? 1 : 0); // (byte|bit)
1912  }
1913 
1914  // Warn if we packed it unnecessarily, when the unpacked alignment is not
1915  // greater than the one after packing, the size in bits doesn't change and
1916  // the offset of each field is identical.
1917  if (Packed && UnpackedAlignment <= Alignment &&
1918  UnpackedSizeInBits == getSizeInBits() && !HasPackedField)
1919  Diag(D->getLocation(), diag::warn_unnecessary_packed)
1920  << Context.getTypeDeclType(RD);
1921  }
1922 }
1923 
1924 void ItaniumRecordLayoutBuilder::UpdateAlignment(
1925  CharUnits NewAlignment, CharUnits UnpackedNewAlignment) {
1926  // The alignment is not modified when using 'mac68k' alignment or when
1927  // we have an externally-supplied layout that also provides overall alignment.
1928  if (IsMac68kAlign || (UseExternalLayout && !InferAlignment))
1929  return;
1930 
1931  if (NewAlignment > Alignment) {
1932  assert(llvm::isPowerOf2_64(NewAlignment.getQuantity()) &&
1933  "Alignment not a power of 2");
1934  Alignment = NewAlignment;
1935  }
1936 
1937  if (UnpackedNewAlignment > UnpackedAlignment) {
1938  assert(llvm::isPowerOf2_64(UnpackedNewAlignment.getQuantity()) &&
1939  "Alignment not a power of 2");
1940  UnpackedAlignment = UnpackedNewAlignment;
1941  }
1942 }
1943 
1944 uint64_t
1945 ItaniumRecordLayoutBuilder::updateExternalFieldOffset(const FieldDecl *Field,
1946  uint64_t ComputedOffset) {
1947  uint64_t ExternalFieldOffset = External.getExternalFieldOffset(Field);
1948 
1949  if (InferAlignment && ExternalFieldOffset < ComputedOffset) {
1950  // The externally-supplied field offset is before the field offset we
1951  // computed. Assume that the structure is packed.
1952  Alignment = CharUnits::One();
1953  InferAlignment = false;
1954  }
1955 
1956  // Use the externally-supplied field offset.
1957  return ExternalFieldOffset;
1958 }
1959 
1960 /// \brief Get diagnostic %select index for tag kind for
1961 /// field padding diagnostic message.
1962 /// WARNING: Indexes apply to particular diagnostics only!
1963 ///
1964 /// \returns diagnostic %select index.
1966  switch (Tag) {
1967  case TTK_Struct: return 0;
1968  case TTK_Interface: return 1;
1969  case TTK_Class: return 2;
1970  default: llvm_unreachable("Invalid tag kind for field padding diagnostic!");
1971  }
1972 }
1973 
1974 void ItaniumRecordLayoutBuilder::CheckFieldPadding(
1975  uint64_t Offset, uint64_t UnpaddedOffset, uint64_t UnpackedOffset,
1976  unsigned UnpackedAlign, bool isPacked, const FieldDecl *D) {
1977  // We let objc ivars without warning, objc interfaces generally are not used
1978  // for padding tricks.
1979  if (isa<ObjCIvarDecl>(D))
1980  return;
1981 
1982  // Don't warn about structs created without a SourceLocation. This can
1983  // be done by clients of the AST, such as codegen.
1984  if (D->getLocation().isInvalid())
1985  return;
1986 
1987  unsigned CharBitNum = Context.getTargetInfo().getCharWidth();
1988 
1989  // Warn if padding was introduced to the struct/class.
1990  if (!IsUnion && Offset > UnpaddedOffset) {
1991  unsigned PadSize = Offset - UnpaddedOffset;
1992  bool InBits = true;
1993  if (PadSize % CharBitNum == 0) {
1994  PadSize = PadSize / CharBitNum;
1995  InBits = false;
1996  }
1997  if (D->getIdentifier())
1998  Diag(D->getLocation(), diag::warn_padded_struct_field)
2000  << Context.getTypeDeclType(D->getParent())
2001  << PadSize
2002  << (InBits ? 1 : 0) // (byte|bit)
2003  << D->getIdentifier();
2004  else
2005  Diag(D->getLocation(), diag::warn_padded_struct_anon_field)
2007  << Context.getTypeDeclType(D->getParent())
2008  << PadSize
2009  << (InBits ? 1 : 0); // (byte|bit)
2010  }
2011  if (isPacked && Offset != UnpackedOffset) {
2012  HasPackedField = true;
2013  }
2014 }
2015 
2017  const CXXRecordDecl *RD) {
2018  // If a class isn't polymorphic it doesn't have a key function.
2019  if (!RD->isPolymorphic())
2020  return nullptr;
2021 
2022  // A class that is not externally visible doesn't have a key function. (Or
2023  // at least, there's no point to assigning a key function to such a class;
2024  // this doesn't affect the ABI.)
2025  if (!RD->isExternallyVisible())
2026  return nullptr;
2027 
2028  // Template instantiations don't have key functions per Itanium C++ ABI 5.2.6.
2029  // Same behavior as GCC.
2031  if (TSK == TSK_ImplicitInstantiation ||
2034  return nullptr;
2035 
2036  bool allowInlineFunctions =
2038 
2039  for (const CXXMethodDecl *MD : RD->methods()) {
2040  if (!MD->isVirtual())
2041  continue;
2042 
2043  if (MD->isPure())
2044  continue;
2045 
2046  // Ignore implicit member functions, they are always marked as inline, but
2047  // they don't have a body until they're defined.
2048  if (MD->isImplicit())
2049  continue;
2050 
2051  if (MD->isInlineSpecified())
2052  continue;
2053 
2054  if (MD->hasInlineBody())
2055  continue;
2056 
2057  // Ignore inline deleted or defaulted functions.
2058  if (!MD->isUserProvided())
2059  continue;
2060 
2061  // In certain ABIs, ignore functions with out-of-line inline definitions.
2062  if (!allowInlineFunctions) {
2063  const FunctionDecl *Def;
2064  if (MD->hasBody(Def) && Def->isInlineSpecified())
2065  continue;
2066  }
2067 
2068  if (Context.getLangOpts().CUDA) {
2069  // While compiler may see key method in this TU, during CUDA
2070  // compilation we should ignore methods that are not accessible
2071  // on this side of compilation.
2072  if (Context.getLangOpts().CUDAIsDevice) {
2073  // In device mode ignore methods without __device__ attribute.
2074  if (!MD->hasAttr<CUDADeviceAttr>())
2075  continue;
2076  } else {
2077  // In host mode ignore __device__-only methods.
2078  if (!MD->hasAttr<CUDAHostAttr>() && MD->hasAttr<CUDADeviceAttr>())
2079  continue;
2080  }
2081  }
2082 
2083  // If the key function is dllimport but the class isn't, then the class has
2084  // no key function. The DLL that exports the key function won't export the
2085  // vtable in this case.
2086  if (MD->hasAttr<DLLImportAttr>() && !RD->hasAttr<DLLImportAttr>())
2087  return nullptr;
2088 
2089  // We found it.
2090  return MD;
2091  }
2092 
2093  return nullptr;
2094 }
2095 
2097  unsigned DiagID) {
2098  return Context.getDiagnostics().Report(Loc, DiagID);
2099 }
2100 
2101 /// Does the target C++ ABI require us to skip over the tail-padding
2102 /// of the given class (considering it as a base class) when allocating
2103 /// objects?
2104 static bool mustSkipTailPadding(TargetCXXABI ABI, const CXXRecordDecl *RD) {
2105  switch (ABI.getTailPaddingUseRules()) {
2107  return false;
2108 
2110  // FIXME: To the extent that this is meant to cover the Itanium ABI
2111  // rules, we should implement the restrictions about over-sized
2112  // bitfields:
2113  //
2114  // http://itanium-cxx-abi.github.io/cxx-abi/abi.html#POD :
2115  // In general, a type is considered a POD for the purposes of
2116  // layout if it is a POD type (in the sense of ISO C++
2117  // [basic.types]). However, a POD-struct or POD-union (in the
2118  // sense of ISO C++ [class]) with a bitfield member whose
2119  // declared width is wider than the declared type of the
2120  // bitfield is not a POD for the purpose of layout. Similarly,
2121  // an array type is not a POD for the purpose of layout if the
2122  // element type of the array is not a POD for the purpose of
2123  // layout.
2124  //
2125  // Where references to the ISO C++ are made in this paragraph,
2126  // the Technical Corrigendum 1 version of the standard is
2127  // intended.
2128  return RD->isPOD();
2129 
2131  // This is equivalent to RD->getTypeForDecl().isCXX11PODType(),
2132  // but with a lot of abstraction penalty stripped off. This does
2133  // assume that these properties are set correctly even in C++98
2134  // mode; fortunately, that is true because we want to assign
2135  // consistently semantics to the type-traits intrinsics (or at
2136  // least as many of them as possible).
2137  return RD->isTrivial() && RD->isCXX11StandardLayout();
2138  }
2139 
2140  llvm_unreachable("bad tail-padding use kind");
2141 }
2142 
2143 static bool isMsLayout(const ASTContext &Context) {
2144  return Context.getTargetInfo().getCXXABI().isMicrosoft();
2145 }
2146 
2147 // This section contains an implementation of struct layout that is, up to the
2148 // included tests, compatible with cl.exe (2013). The layout produced is
2149 // significantly different than those produced by the Itanium ABI. Here we note
2150 // the most important differences.
2151 //
2152 // * The alignment of bitfields in unions is ignored when computing the
2153 // alignment of the union.
2154 // * The existence of zero-width bitfield that occurs after anything other than
2155 // a non-zero length bitfield is ignored.
2156 // * There is no explicit primary base for the purposes of layout. All bases
2157 // with vfptrs are laid out first, followed by all bases without vfptrs.
2158 // * The Itanium equivalent vtable pointers are split into a vfptr (virtual
2159 // function pointer) and a vbptr (virtual base pointer). They can each be
2160 // shared with a, non-virtual bases. These bases need not be the same. vfptrs
2161 // always occur at offset 0. vbptrs can occur at an arbitrary offset and are
2162 // placed after the lexicographically last non-virtual base. This placement
2163 // is always before fields but can be in the middle of the non-virtual bases
2164 // due to the two-pass layout scheme for non-virtual-bases.
2165 // * Virtual bases sometimes require a 'vtordisp' field that is laid out before
2166 // the virtual base and is used in conjunction with virtual overrides during
2167 // construction and destruction. This is always a 4 byte value and is used as
2168 // an alternative to constructor vtables.
2169 // * vtordisps are allocated in a block of memory with size and alignment equal
2170 // to the alignment of the completed structure (before applying __declspec(
2171 // align())). The vtordisp always occur at the end of the allocation block,
2172 // immediately prior to the virtual base.
2173 // * vfptrs are injected after all bases and fields have been laid out. In
2174 // order to guarantee proper alignment of all fields, the vfptr injection
2175 // pushes all bases and fields back by the alignment imposed by those bases
2176 // and fields. This can potentially add a significant amount of padding.
2177 // vfptrs are always injected at offset 0.
2178 // * vbptrs are injected after all bases and fields have been laid out. In
2179 // order to guarantee proper alignment of all fields, the vfptr injection
2180 // pushes all bases and fields back by the alignment imposed by those bases
2181 // and fields. This can potentially add a significant amount of padding.
2182 // vbptrs are injected immediately after the last non-virtual base as
2183 // lexicographically ordered in the code. If this site isn't pointer aligned
2184 // the vbptr is placed at the next properly aligned location. Enough padding
2185 // is added to guarantee a fit.
2186 // * The last zero sized non-virtual base can be placed at the end of the
2187 // struct (potentially aliasing another object), or may alias with the first
2188 // field, even if they are of the same type.
2189 // * The last zero size virtual base may be placed at the end of the struct
2190 // potentially aliasing another object.
2191 // * The ABI attempts to avoid aliasing of zero sized bases by adding padding
2192 // between bases or vbases with specific properties. The criteria for
2193 // additional padding between two bases is that the first base is zero sized
2194 // or ends with a zero sized subobject and the second base is zero sized or
2195 // trails with a zero sized base or field (sharing of vfptrs can reorder the
2196 // layout of the so the leading base is not always the first one declared).
2197 // This rule does take into account fields that are not records, so padding
2198 // will occur even if the last field is, e.g. an int. The padding added for
2199 // bases is 1 byte. The padding added between vbases depends on the alignment
2200 // of the object but is at least 4 bytes (in both 32 and 64 bit modes).
2201 // * There is no concept of non-virtual alignment, non-virtual alignment and
2202 // alignment are always identical.
2203 // * There is a distinction between alignment and required alignment.
2204 // __declspec(align) changes the required alignment of a struct. This
2205 // alignment is _always_ obeyed, even in the presence of #pragma pack. A
2206 // record inherits required alignment from all of its fields and bases.
2207 // * __declspec(align) on bitfields has the effect of changing the bitfield's
2208 // alignment instead of its required alignment. This is the only known way
2209 // to make the alignment of a struct bigger than 8. Interestingly enough
2210 // this alignment is also immune to the effects of #pragma pack and can be
2211 // used to create structures with large alignment under #pragma pack.
2212 // However, because it does not impact required alignment, such a structure,
2213 // when used as a field or base, will not be aligned if #pragma pack is
2214 // still active at the time of use.
2215 //
2216 // Known incompatibilities:
2217 // * all: #pragma pack between fields in a record
2218 // * 2010 and back: If the last field in a record is a bitfield, every object
2219 // laid out after the record will have extra padding inserted before it. The
2220 // extra padding will have size equal to the size of the storage class of the
2221 // bitfield. 0 sized bitfields don't exhibit this behavior and the extra
2222 // padding can be avoided by adding a 0 sized bitfield after the non-zero-
2223 // sized bitfield.
2224 // * 2012 and back: In 64-bit mode, if the alignment of a record is 16 or
2225 // greater due to __declspec(align()) then a second layout phase occurs after
2226 // The locations of the vf and vb pointers are known. This layout phase
2227 // suffers from the "last field is a bitfield" bug in 2010 and results in
2228 // _every_ field getting padding put in front of it, potentially including the
2229 // vfptr, leaving the vfprt at a non-zero location which results in a fault if
2230 // anything tries to read the vftbl. The second layout phase also treats
2231 // bitfields as separate entities and gives them each storage rather than
2232 // packing them. Additionally, because this phase appears to perform a
2233 // (an unstable) sort on the members before laying them out and because merged
2234 // bitfields have the same address, the bitfields end up in whatever order
2235 // the sort left them in, a behavior we could never hope to replicate.
2236 
2237 namespace {
2238 struct MicrosoftRecordLayoutBuilder {
2239  struct ElementInfo {
2240  CharUnits Size;
2241  CharUnits Alignment;
2242  };
2243  typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsetsMapTy;
2244  MicrosoftRecordLayoutBuilder(const ASTContext &Context) : Context(Context) {}
2245 private:
2246  MicrosoftRecordLayoutBuilder(const MicrosoftRecordLayoutBuilder &) = delete;
2247  void operator=(const MicrosoftRecordLayoutBuilder &) = delete;
2248 public:
2249  void layout(const RecordDecl *RD);
2250  void cxxLayout(const CXXRecordDecl *RD);
2251  /// \brief Initializes size and alignment and honors some flags.
2252  void initializeLayout(const RecordDecl *RD);
2253  /// \brief Initialized C++ layout, compute alignment and virtual alignment and
2254  /// existence of vfptrs and vbptrs. Alignment is needed before the vfptr is
2255  /// laid out.
2256  void initializeCXXLayout(const CXXRecordDecl *RD);
2257  void layoutNonVirtualBases(const CXXRecordDecl *RD);
2258  void layoutNonVirtualBase(const CXXRecordDecl *RD,
2259  const CXXRecordDecl *BaseDecl,
2260  const ASTRecordLayout &BaseLayout,
2261  const ASTRecordLayout *&PreviousBaseLayout);
2262  void injectVFPtr(const CXXRecordDecl *RD);
2263  void injectVBPtr(const CXXRecordDecl *RD);
2264  /// \brief Lays out the fields of the record. Also rounds size up to
2265  /// alignment.
2266  void layoutFields(const RecordDecl *RD);
2267  void layoutField(const FieldDecl *FD);
2268  void layoutBitField(const FieldDecl *FD);
2269  /// \brief Lays out a single zero-width bit-field in the record and handles
2270  /// special cases associated with zero-width bit-fields.
2271  void layoutZeroWidthBitField(const FieldDecl *FD);
2272  void layoutVirtualBases(const CXXRecordDecl *RD);
2273  void finalizeLayout(const RecordDecl *RD);
2274  /// \brief Gets the size and alignment of a base taking pragma pack and
2275  /// __declspec(align) into account.
2276  ElementInfo getAdjustedElementInfo(const ASTRecordLayout &Layout);
2277  /// \brief Gets the size and alignment of a field taking pragma pack and
2278  /// __declspec(align) into account. It also updates RequiredAlignment as a
2279  /// side effect because it is most convenient to do so here.
2280  ElementInfo getAdjustedElementInfo(const FieldDecl *FD);
2281  /// \brief Places a field at an offset in CharUnits.
2282  void placeFieldAtOffset(CharUnits FieldOffset) {
2283  FieldOffsets.push_back(Context.toBits(FieldOffset));
2284  }
2285  /// \brief Places a bitfield at a bit offset.
2286  void placeFieldAtBitOffset(uint64_t FieldOffset) {
2287  FieldOffsets.push_back(FieldOffset);
2288  }
2289  /// \brief Compute the set of virtual bases for which vtordisps are required.
2290  void computeVtorDispSet(
2291  llvm::SmallPtrSetImpl<const CXXRecordDecl *> &HasVtorDispSet,
2292  const CXXRecordDecl *RD) const;
2293  const ASTContext &Context;
2294  /// \brief The size of the record being laid out.
2295  CharUnits Size;
2296  /// \brief The non-virtual size of the record layout.
2297  CharUnits NonVirtualSize;
2298  /// \brief The data size of the record layout.
2299  CharUnits DataSize;
2300  /// \brief The current alignment of the record layout.
2301  CharUnits Alignment;
2302  /// \brief The maximum allowed field alignment. This is set by #pragma pack.
2303  CharUnits MaxFieldAlignment;
2304  /// \brief The alignment that this record must obey. This is imposed by
2305  /// __declspec(align()) on the record itself or one of its fields or bases.
2306  CharUnits RequiredAlignment;
2307  /// \brief The size of the allocation of the currently active bitfield.
2308  /// This value isn't meaningful unless LastFieldIsNonZeroWidthBitfield
2309  /// is true.
2310  CharUnits CurrentBitfieldSize;
2311  /// \brief Offset to the virtual base table pointer (if one exists).
2312  CharUnits VBPtrOffset;
2313  /// \brief Minimum record size possible.
2314  CharUnits MinEmptyStructSize;
2315  /// \brief The size and alignment info of a pointer.
2316  ElementInfo PointerInfo;
2317  /// \brief The primary base class (if one exists).
2318  const CXXRecordDecl *PrimaryBase;
2319  /// \brief The class we share our vb-pointer with.
2320  const CXXRecordDecl *SharedVBPtrBase;
2321  /// \brief The collection of field offsets.
2322  SmallVector<uint64_t, 16> FieldOffsets;
2323  /// \brief Base classes and their offsets in the record.
2324  BaseOffsetsMapTy Bases;
2325  /// \brief virtual base classes and their offsets in the record.
2327  /// \brief The number of remaining bits in our last bitfield allocation.
2328  /// This value isn't meaningful unless LastFieldIsNonZeroWidthBitfield is
2329  /// true.
2330  unsigned RemainingBitsInField;
2331  bool IsUnion : 1;
2332  /// \brief True if the last field laid out was a bitfield and was not 0
2333  /// width.
2334  bool LastFieldIsNonZeroWidthBitfield : 1;
2335  /// \brief True if the class has its own vftable pointer.
2336  bool HasOwnVFPtr : 1;
2337  /// \brief True if the class has a vbtable pointer.
2338  bool HasVBPtr : 1;
2339  /// \brief True if the last sub-object within the type is zero sized or the
2340  /// object itself is zero sized. This *does not* count members that are not
2341  /// records. Only used for MS-ABI.
2342  bool EndsWithZeroSizedObject : 1;
2343  /// \brief True if this class is zero sized or first base is zero sized or
2344  /// has this property. Only used for MS-ABI.
2345  bool LeadsWithZeroSizedBase : 1;
2346 
2347  /// \brief True if the external AST source provided a layout for this record.
2348  bool UseExternalLayout : 1;
2349 
2350  /// \brief The layout provided by the external AST source. Only active if
2351  /// UseExternalLayout is true.
2352  ExternalLayout External;
2353 };
2354 } // namespace
2355 
2356 MicrosoftRecordLayoutBuilder::ElementInfo
2357 MicrosoftRecordLayoutBuilder::getAdjustedElementInfo(
2358  const ASTRecordLayout &Layout) {
2359  ElementInfo Info;
2360  Info.Alignment = Layout.getAlignment();
2361  // Respect pragma pack.
2362  if (!MaxFieldAlignment.isZero())
2363  Info.Alignment = std::min(Info.Alignment, MaxFieldAlignment);
2364  // Track zero-sized subobjects here where it's already available.
2365  EndsWithZeroSizedObject = Layout.endsWithZeroSizedObject();
2366  // Respect required alignment, this is necessary because we may have adjusted
2367  // the alignment in the case of pragam pack. Note that the required alignment
2368  // doesn't actually apply to the struct alignment at this point.
2369  Alignment = std::max(Alignment, Info.Alignment);
2370  RequiredAlignment = std::max(RequiredAlignment, Layout.getRequiredAlignment());
2371  Info.Alignment = std::max(Info.Alignment, Layout.getRequiredAlignment());
2372  Info.Size = Layout.getNonVirtualSize();
2373  return Info;
2374 }
2375 
2376 MicrosoftRecordLayoutBuilder::ElementInfo
2377 MicrosoftRecordLayoutBuilder::getAdjustedElementInfo(
2378  const FieldDecl *FD) {
2379  // Get the alignment of the field type's natural alignment, ignore any
2380  // alignment attributes.
2381  ElementInfo Info;
2382  std::tie(Info.Size, Info.Alignment) =
2384  // Respect align attributes on the field.
2385  CharUnits FieldRequiredAlignment =
2386  Context.toCharUnitsFromBits(FD->getMaxAlignment());
2387  // Respect align attributes on the type.
2388  if (Context.isAlignmentRequired(FD->getType()))
2389  FieldRequiredAlignment = std::max(
2390  Context.getTypeAlignInChars(FD->getType()), FieldRequiredAlignment);
2391  // Respect attributes applied to subobjects of the field.
2392  if (FD->isBitField())
2393  // For some reason __declspec align impacts alignment rather than required
2394  // alignment when it is applied to bitfields.
2395  Info.Alignment = std::max(Info.Alignment, FieldRequiredAlignment);
2396  else {
2397  if (auto RT =
2399  auto const &Layout = Context.getASTRecordLayout(RT->getDecl());
2400  EndsWithZeroSizedObject = Layout.endsWithZeroSizedObject();
2401  FieldRequiredAlignment = std::max(FieldRequiredAlignment,
2402  Layout.getRequiredAlignment());
2403  }
2404  // Capture required alignment as a side-effect.
2405  RequiredAlignment = std::max(RequiredAlignment, FieldRequiredAlignment);
2406  }
2407  // Respect pragma pack, attribute pack and declspec align
2408  if (!MaxFieldAlignment.isZero())
2409  Info.Alignment = std::min(Info.Alignment, MaxFieldAlignment);
2410  if (FD->hasAttr<PackedAttr>())
2411  Info.Alignment = CharUnits::One();
2412  Info.Alignment = std::max(Info.Alignment, FieldRequiredAlignment);
2413  return Info;
2414 }
2415 
2416 void MicrosoftRecordLayoutBuilder::layout(const RecordDecl *RD) {
2417  // For C record layout, zero-sized records always have size 4.
2418  MinEmptyStructSize = CharUnits::fromQuantity(4);
2419  initializeLayout(RD);
2420  layoutFields(RD);
2421  DataSize = Size = Size.alignTo(Alignment);
2422  RequiredAlignment = std::max(
2423  RequiredAlignment, Context.toCharUnitsFromBits(RD->getMaxAlignment()));
2424  finalizeLayout(RD);
2425 }
2426 
2427 void MicrosoftRecordLayoutBuilder::cxxLayout(const CXXRecordDecl *RD) {
2428  // The C++ standard says that empty structs have size 1.
2429  MinEmptyStructSize = CharUnits::One();
2430  initializeLayout(RD);
2431  initializeCXXLayout(RD);
2432  layoutNonVirtualBases(RD);
2433  layoutFields(RD);
2434  injectVBPtr(RD);
2435  injectVFPtr(RD);
2436  if (HasOwnVFPtr || (HasVBPtr && !SharedVBPtrBase))
2437  Alignment = std::max(Alignment, PointerInfo.Alignment);
2438  auto RoundingAlignment = Alignment;
2439  if (!MaxFieldAlignment.isZero())
2440  RoundingAlignment = std::min(RoundingAlignment, MaxFieldAlignment);
2441  NonVirtualSize = Size = Size.alignTo(RoundingAlignment);
2442  RequiredAlignment = std::max(
2443  RequiredAlignment, Context.toCharUnitsFromBits(RD->getMaxAlignment()));
2444  layoutVirtualBases(RD);
2445  finalizeLayout(RD);
2446 }
2447 
2448 void MicrosoftRecordLayoutBuilder::initializeLayout(const RecordDecl *RD) {
2449  IsUnion = RD->isUnion();
2450  Size = CharUnits::Zero();
2451  Alignment = CharUnits::One();
2452  // In 64-bit mode we always perform an alignment step after laying out vbases.
2453  // In 32-bit mode we do not. The check to see if we need to perform alignment
2454  // checks the RequiredAlignment field and performs alignment if it isn't 0.
2455  RequiredAlignment = Context.getTargetInfo().getTriple().isArch64Bit()
2456  ? CharUnits::One()
2457  : CharUnits::Zero();
2458  // Compute the maximum field alignment.
2459  MaxFieldAlignment = CharUnits::Zero();
2460  // Honor the default struct packing maximum alignment flag.
2461  if (unsigned DefaultMaxFieldAlignment = Context.getLangOpts().PackStruct)
2462  MaxFieldAlignment = CharUnits::fromQuantity(DefaultMaxFieldAlignment);
2463  // Honor the packing attribute. The MS-ABI ignores pragma pack if its larger
2464  // than the pointer size.
2465  if (const MaxFieldAlignmentAttr *MFAA = RD->getAttr<MaxFieldAlignmentAttr>()){
2466  unsigned PackedAlignment = MFAA->getAlignment();
2467  if (PackedAlignment <= Context.getTargetInfo().getPointerWidth(0))
2468  MaxFieldAlignment = Context.toCharUnitsFromBits(PackedAlignment);
2469  }
2470  // Packed attribute forces max field alignment to be 1.
2471  if (RD->hasAttr<PackedAttr>())
2472  MaxFieldAlignment = CharUnits::One();
2473 
2474  // Try to respect the external layout if present.
2475  UseExternalLayout = false;
2476  if (ExternalASTSource *Source = Context.getExternalSource())
2477  UseExternalLayout = Source->layoutRecordType(
2478  RD, External.Size, External.Align, External.FieldOffsets,
2479  External.BaseOffsets, External.VirtualBaseOffsets);
2480 }
2481 
2482 void
2483 MicrosoftRecordLayoutBuilder::initializeCXXLayout(const CXXRecordDecl *RD) {
2484  EndsWithZeroSizedObject = false;
2485  LeadsWithZeroSizedBase = false;
2486  HasOwnVFPtr = false;
2487  HasVBPtr = false;
2488  PrimaryBase = nullptr;
2489  SharedVBPtrBase = nullptr;
2490  // Calculate pointer size and alignment. These are used for vfptr and vbprt
2491  // injection.
2492  PointerInfo.Size =
2493  Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
2494  PointerInfo.Alignment =
2495  Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerAlign(0));
2496  // Respect pragma pack.
2497  if (!MaxFieldAlignment.isZero())
2498  PointerInfo.Alignment = std::min(PointerInfo.Alignment, MaxFieldAlignment);
2499 }
2500 
2501 void
2502 MicrosoftRecordLayoutBuilder::layoutNonVirtualBases(const CXXRecordDecl *RD) {
2503  // The MS-ABI lays out all bases that contain leading vfptrs before it lays
2504  // out any bases that do not contain vfptrs. We implement this as two passes
2505  // over the bases. This approach guarantees that the primary base is laid out
2506  // first. We use these passes to calculate some additional aggregated
2507  // information about the bases, such as required alignment and the presence of
2508  // zero sized members.
2509  const ASTRecordLayout *PreviousBaseLayout = nullptr;
2510  // Iterate through the bases and lay out the non-virtual ones.
2511  for (const CXXBaseSpecifier &Base : RD->bases()) {
2512  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2513  const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2514  // Mark and skip virtual bases.
2515  if (Base.isVirtual()) {
2516  HasVBPtr = true;
2517  continue;
2518  }
2519  // Check for a base to share a VBPtr with.
2520  if (!SharedVBPtrBase && BaseLayout.hasVBPtr()) {
2521  SharedVBPtrBase = BaseDecl;
2522  HasVBPtr = true;
2523  }
2524  // Only lay out bases with extendable VFPtrs on the first pass.
2525  if (!BaseLayout.hasExtendableVFPtr())
2526  continue;
2527  // If we don't have a primary base, this one qualifies.
2528  if (!PrimaryBase) {
2529  PrimaryBase = BaseDecl;
2530  LeadsWithZeroSizedBase = BaseLayout.leadsWithZeroSizedBase();
2531  }
2532  // Lay out the base.
2533  layoutNonVirtualBase(RD, BaseDecl, BaseLayout, PreviousBaseLayout);
2534  }
2535  // Figure out if we need a fresh VFPtr for this class.
2536  if (!PrimaryBase && RD->isDynamicClass())
2538  e = RD->method_end();
2539  !HasOwnVFPtr && i != e; ++i)
2540  HasOwnVFPtr = i->isVirtual() && i->size_overridden_methods() == 0;
2541  // If we don't have a primary base then we have a leading object that could
2542  // itself lead with a zero-sized object, something we track.
2543  bool CheckLeadingLayout = !PrimaryBase;
2544  // Iterate through the bases and lay out the non-virtual ones.
2545  for (const CXXBaseSpecifier &Base : RD->bases()) {
2546  if (Base.isVirtual())
2547  continue;
2548  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2549  const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2550  // Only lay out bases without extendable VFPtrs on the second pass.
2551  if (BaseLayout.hasExtendableVFPtr()) {
2552  VBPtrOffset = Bases[BaseDecl] + BaseLayout.getNonVirtualSize();
2553  continue;
2554  }
2555  // If this is the first layout, check to see if it leads with a zero sized
2556  // object. If it does, so do we.
2557  if (CheckLeadingLayout) {
2558  CheckLeadingLayout = false;
2559  LeadsWithZeroSizedBase = BaseLayout.leadsWithZeroSizedBase();
2560  }
2561  // Lay out the base.
2562  layoutNonVirtualBase(RD, BaseDecl, BaseLayout, PreviousBaseLayout);
2563  VBPtrOffset = Bases[BaseDecl] + BaseLayout.getNonVirtualSize();
2564  }
2565  // Set our VBPtroffset if we know it at this point.
2566  if (!HasVBPtr)
2567  VBPtrOffset = CharUnits::fromQuantity(-1);
2568  else if (SharedVBPtrBase) {
2569  const ASTRecordLayout &Layout = Context.getASTRecordLayout(SharedVBPtrBase);
2570  VBPtrOffset = Bases[SharedVBPtrBase] + Layout.getVBPtrOffset();
2571  }
2572 }
2573 
2574 static bool recordUsesEBO(const RecordDecl *RD) {
2575  if (!isa<CXXRecordDecl>(RD))
2576  return false;
2577  if (RD->hasAttr<EmptyBasesAttr>())
2578  return true;
2579  if (auto *LVA = RD->getAttr<LayoutVersionAttr>())
2580  // TODO: Double check with the next version of MSVC.
2581  if (LVA->getVersion() <= LangOptions::MSVC2015)
2582  return false;
2583  // TODO: Some later version of MSVC will change the default behavior of the
2584  // compiler to enable EBO by default. When this happens, we will need an
2585  // additional isCompatibleWithMSVC check.
2586  return false;
2587 }
2588 
2589 void MicrosoftRecordLayoutBuilder::layoutNonVirtualBase(
2590  const CXXRecordDecl *RD,
2591  const CXXRecordDecl *BaseDecl,
2592  const ASTRecordLayout &BaseLayout,
2593  const ASTRecordLayout *&PreviousBaseLayout) {
2594  // Insert padding between two bases if the left first one is zero sized or
2595  // contains a zero sized subobject and the right is zero sized or one leads
2596  // with a zero sized base.
2597  bool MDCUsesEBO = recordUsesEBO(RD);
2598  if (PreviousBaseLayout && PreviousBaseLayout->endsWithZeroSizedObject() &&
2599  BaseLayout.leadsWithZeroSizedBase() && !MDCUsesEBO)
2600  Size++;
2601  ElementInfo Info = getAdjustedElementInfo(BaseLayout);
2602  CharUnits BaseOffset;
2603 
2604  // Respect the external AST source base offset, if present.
2605  bool FoundBase = false;
2606  if (UseExternalLayout) {
2607  FoundBase = External.getExternalNVBaseOffset(BaseDecl, BaseOffset);
2608  if (FoundBase) {
2609  assert(BaseOffset >= Size && "base offset already allocated");
2610  Size = BaseOffset;
2611  }
2612  }
2613 
2614  if (!FoundBase) {
2615  if (MDCUsesEBO && BaseDecl->isEmpty() &&
2616  BaseLayout.getNonVirtualSize() == CharUnits::Zero()) {
2617  BaseOffset = CharUnits::Zero();
2618  } else {
2619  // Otherwise, lay the base out at the end of the MDC.
2620  BaseOffset = Size = Size.alignTo(Info.Alignment);
2621  }
2622  }
2623  Bases.insert(std::make_pair(BaseDecl, BaseOffset));
2624  Size += BaseLayout.getNonVirtualSize();
2625  PreviousBaseLayout = &BaseLayout;
2626 }
2627 
2628 void MicrosoftRecordLayoutBuilder::layoutFields(const RecordDecl *RD) {
2629  LastFieldIsNonZeroWidthBitfield = false;
2630  for (const FieldDecl *Field : RD->fields())
2631  layoutField(Field);
2632 }
2633 
2634 void MicrosoftRecordLayoutBuilder::layoutField(const FieldDecl *FD) {
2635  if (FD->isBitField()) {
2636  layoutBitField(FD);
2637  return;
2638  }
2639  LastFieldIsNonZeroWidthBitfield = false;
2640  ElementInfo Info = getAdjustedElementInfo(FD);
2641  Alignment = std::max(Alignment, Info.Alignment);
2642  if (IsUnion) {
2643  placeFieldAtOffset(CharUnits::Zero());
2644  Size = std::max(Size, Info.Size);
2645  } else {
2646  CharUnits FieldOffset;
2647  if (UseExternalLayout) {
2648  FieldOffset =
2649  Context.toCharUnitsFromBits(External.getExternalFieldOffset(FD));
2650  assert(FieldOffset >= Size && "field offset already allocated");
2651  } else {
2652  FieldOffset = Size.alignTo(Info.Alignment);
2653  }
2654  placeFieldAtOffset(FieldOffset);
2655  Size = FieldOffset + Info.Size;
2656  }
2657 }
2658 
2659 void MicrosoftRecordLayoutBuilder::layoutBitField(const FieldDecl *FD) {
2660  unsigned Width = FD->getBitWidthValue(Context);
2661  if (Width == 0) {
2662  layoutZeroWidthBitField(FD);
2663  return;
2664  }
2665  ElementInfo Info = getAdjustedElementInfo(FD);
2666  // Clamp the bitfield to a containable size for the sake of being able
2667  // to lay them out. Sema will throw an error.
2668  if (Width > Context.toBits(Info.Size))
2669  Width = Context.toBits(Info.Size);
2670  // Check to see if this bitfield fits into an existing allocation. Note:
2671  // MSVC refuses to pack bitfields of formal types with different sizes
2672  // into the same allocation.
2673  if (!IsUnion && LastFieldIsNonZeroWidthBitfield &&
2674  CurrentBitfieldSize == Info.Size && Width <= RemainingBitsInField) {
2675  placeFieldAtBitOffset(Context.toBits(Size) - RemainingBitsInField);
2676  RemainingBitsInField -= Width;
2677  return;
2678  }
2679  LastFieldIsNonZeroWidthBitfield = true;
2680  CurrentBitfieldSize = Info.Size;
2681  if (IsUnion) {
2682  placeFieldAtOffset(CharUnits::Zero());
2683  Size = std::max(Size, Info.Size);
2684  // TODO: Add a Sema warning that MS ignores bitfield alignment in unions.
2685  } else {
2686  // Allocate a new block of memory and place the bitfield in it.
2687  CharUnits FieldOffset = Size.alignTo(Info.Alignment);
2688  placeFieldAtOffset(FieldOffset);
2689  Size = FieldOffset + Info.Size;
2690  Alignment = std::max(Alignment, Info.Alignment);
2691  RemainingBitsInField = Context.toBits(Info.Size) - Width;
2692  }
2693 }
2694 
2695 void
2696 MicrosoftRecordLayoutBuilder::layoutZeroWidthBitField(const FieldDecl *FD) {
2697  // Zero-width bitfields are ignored unless they follow a non-zero-width
2698  // bitfield.
2699  if (!LastFieldIsNonZeroWidthBitfield) {
2700  placeFieldAtOffset(IsUnion ? CharUnits::Zero() : Size);
2701  // TODO: Add a Sema warning that MS ignores alignment for zero
2702  // sized bitfields that occur after zero-size bitfields or non-bitfields.
2703  return;
2704  }
2705  LastFieldIsNonZeroWidthBitfield = false;
2706  ElementInfo Info = getAdjustedElementInfo(FD);
2707  if (IsUnion) {
2708  placeFieldAtOffset(CharUnits::Zero());
2709  Size = std::max(Size, Info.Size);
2710  // TODO: Add a Sema warning that MS ignores bitfield alignment in unions.
2711  } else {
2712  // Round up the current record size to the field's alignment boundary.
2713  CharUnits FieldOffset = Size.alignTo(Info.Alignment);
2714  placeFieldAtOffset(FieldOffset);
2715  Size = FieldOffset;
2716  Alignment = std::max(Alignment, Info.Alignment);
2717  }
2718 }
2719 
2720 void MicrosoftRecordLayoutBuilder::injectVBPtr(const CXXRecordDecl *RD) {
2721  if (!HasVBPtr || SharedVBPtrBase)
2722  return;
2723  // Inject the VBPointer at the injection site.
2724  CharUnits InjectionSite = VBPtrOffset;
2725  // But before we do, make sure it's properly aligned.
2726  VBPtrOffset = VBPtrOffset.alignTo(PointerInfo.Alignment);
2727  // Shift everything after the vbptr down, unless we're using an external
2728  // layout.
2729  if (UseExternalLayout)
2730  return;
2731  // Determine where the first field should be laid out after the vbptr.
2732  CharUnits FieldStart = VBPtrOffset + PointerInfo.Size;
2733  // Make sure that the amount we push the fields back by is a multiple of the
2734  // alignment.
2735  CharUnits Offset = (FieldStart - InjectionSite)
2736  .alignTo(std::max(RequiredAlignment, Alignment));
2737  Size += Offset;
2738  for (uint64_t &FieldOffset : FieldOffsets)
2739  FieldOffset += Context.toBits(Offset);
2740  for (BaseOffsetsMapTy::value_type &Base : Bases)
2741  if (Base.second >= InjectionSite)
2742  Base.second += Offset;
2743 }
2744 
2745 void MicrosoftRecordLayoutBuilder::injectVFPtr(const CXXRecordDecl *RD) {
2746  if (!HasOwnVFPtr)
2747  return;
2748  // Make sure that the amount we push the struct back by is a multiple of the
2749  // alignment.
2750  CharUnits Offset =
2751  PointerInfo.Size.alignTo(std::max(RequiredAlignment, Alignment));
2752  // Push back the vbptr, but increase the size of the object and push back
2753  // regular fields by the offset only if not using external record layout.
2754  if (HasVBPtr)
2755  VBPtrOffset += Offset;
2756 
2757  if (UseExternalLayout)
2758  return;
2759 
2760  Size += Offset;
2761 
2762  // If we're using an external layout, the fields offsets have already
2763  // accounted for this adjustment.
2764  for (uint64_t &FieldOffset : FieldOffsets)
2765  FieldOffset += Context.toBits(Offset);
2766  for (BaseOffsetsMapTy::value_type &Base : Bases)
2767  Base.second += Offset;
2768 }
2769 
2770 void MicrosoftRecordLayoutBuilder::layoutVirtualBases(const CXXRecordDecl *RD) {
2771  if (!HasVBPtr)
2772  return;
2773  // Vtordisps are always 4 bytes (even in 64-bit mode)
2774  CharUnits VtorDispSize = CharUnits::fromQuantity(4);
2775  CharUnits VtorDispAlignment = VtorDispSize;
2776  // vtordisps respect pragma pack.
2777  if (!MaxFieldAlignment.isZero())
2778  VtorDispAlignment = std::min(VtorDispAlignment, MaxFieldAlignment);
2779  // The alignment of the vtordisp is at least the required alignment of the
2780  // entire record. This requirement may be present to support vtordisp
2781  // injection.
2782  for (const CXXBaseSpecifier &VBase : RD->vbases()) {
2783  const CXXRecordDecl *BaseDecl = VBase.getType()->getAsCXXRecordDecl();
2784  const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2785  RequiredAlignment =
2786  std::max(RequiredAlignment, BaseLayout.getRequiredAlignment());
2787  }
2788  VtorDispAlignment = std::max(VtorDispAlignment, RequiredAlignment);
2789  // Compute the vtordisp set.
2790  llvm::SmallPtrSet<const CXXRecordDecl *, 2> HasVtorDispSet;
2791  computeVtorDispSet(HasVtorDispSet, RD);
2792  // Iterate through the virtual bases and lay them out.
2793  const ASTRecordLayout *PreviousBaseLayout = nullptr;
2794  for (const CXXBaseSpecifier &VBase : RD->vbases()) {
2795  const CXXRecordDecl *BaseDecl = VBase.getType()->getAsCXXRecordDecl();
2796  const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2797  bool HasVtordisp = HasVtorDispSet.count(BaseDecl) > 0;
2798  // Insert padding between two bases if the left first one is zero sized or
2799  // contains a zero sized subobject and the right is zero sized or one leads
2800  // with a zero sized base. The padding between virtual bases is 4
2801  // bytes (in both 32 and 64 bits modes) and always involves rounding up to
2802  // the required alignment, we don't know why.
2803  if ((PreviousBaseLayout && PreviousBaseLayout->endsWithZeroSizedObject() &&
2804  BaseLayout.leadsWithZeroSizedBase() && !recordUsesEBO(RD)) ||
2805  HasVtordisp) {
2806  Size = Size.alignTo(VtorDispAlignment) + VtorDispSize;
2807  Alignment = std::max(VtorDispAlignment, Alignment);
2808  }
2809  // Insert the virtual base.
2810  ElementInfo Info = getAdjustedElementInfo(BaseLayout);
2811  CharUnits BaseOffset;
2812 
2813  // Respect the external AST source base offset, if present.
2814  bool FoundBase = false;
2815  if (UseExternalLayout) {
2816  FoundBase = External.getExternalVBaseOffset(BaseDecl, BaseOffset);
2817  if (FoundBase)
2818  assert(BaseOffset >= Size && "base offset already allocated");
2819  }
2820  if (!FoundBase)
2821  BaseOffset = Size.alignTo(Info.Alignment);
2822 
2823  VBases.insert(std::make_pair(BaseDecl,
2824  ASTRecordLayout::VBaseInfo(BaseOffset, HasVtordisp)));
2825  Size = BaseOffset + BaseLayout.getNonVirtualSize();
2826  PreviousBaseLayout = &BaseLayout;
2827  }
2828 }
2829 
2830 void MicrosoftRecordLayoutBuilder::finalizeLayout(const RecordDecl *RD) {
2831  // Respect required alignment. Note that in 32-bit mode Required alignment
2832  // may be 0 and cause size not to be updated.
2833  DataSize = Size;
2834  if (!RequiredAlignment.isZero()) {
2835  Alignment = std::max(Alignment, RequiredAlignment);
2836  auto RoundingAlignment = Alignment;
2837  if (!MaxFieldAlignment.isZero())
2838  RoundingAlignment = std::min(RoundingAlignment, MaxFieldAlignment);
2839  RoundingAlignment = std::max(RoundingAlignment, RequiredAlignment);
2840  Size = Size.alignTo(RoundingAlignment);
2841  }
2842  if (Size.isZero()) {
2843  if (!recordUsesEBO(RD) || !cast<CXXRecordDecl>(RD)->isEmpty()) {
2844  EndsWithZeroSizedObject = true;
2845  LeadsWithZeroSizedBase = true;
2846  }
2847  // Zero-sized structures have size equal to their alignment if a
2848  // __declspec(align) came into play.
2849  if (RequiredAlignment >= MinEmptyStructSize)
2850  Size = Alignment;
2851  else
2852  Size = MinEmptyStructSize;
2853  }
2854 
2855  if (UseExternalLayout) {
2856  Size = Context.toCharUnitsFromBits(External.Size);
2857  if (External.Align)
2858  Alignment = Context.toCharUnitsFromBits(External.Align);
2859  }
2860 }
2861 
2862 // Recursively walks the non-virtual bases of a class and determines if any of
2863 // them are in the bases with overridden methods set.
2864 static bool
2865 RequiresVtordisp(const llvm::SmallPtrSetImpl<const CXXRecordDecl *> &
2866  BasesWithOverriddenMethods,
2867  const CXXRecordDecl *RD) {
2868  if (BasesWithOverriddenMethods.count(RD))
2869  return true;
2870  // If any of a virtual bases non-virtual bases (recursively) requires a
2871  // vtordisp than so does this virtual base.
2872  for (const CXXBaseSpecifier &Base : RD->bases())
2873  if (!Base.isVirtual() &&
2874  RequiresVtordisp(BasesWithOverriddenMethods,
2875  Base.getType()->getAsCXXRecordDecl()))
2876  return true;
2877  return false;
2878 }
2879 
2880 void MicrosoftRecordLayoutBuilder::computeVtorDispSet(
2881  llvm::SmallPtrSetImpl<const CXXRecordDecl *> &HasVtordispSet,
2882  const CXXRecordDecl *RD) const {
2883  // /vd2 or #pragma vtordisp(2): Always use vtordisps for virtual bases with
2884  // vftables.
2885  if (RD->getMSVtorDispMode() == MSVtorDispAttr::ForVFTable) {
2886  for (const CXXBaseSpecifier &Base : RD->vbases()) {
2887  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2888  const ASTRecordLayout &Layout = Context.getASTRecordLayout(BaseDecl);
2889  if (Layout.hasExtendableVFPtr())
2890  HasVtordispSet.insert(BaseDecl);
2891  }
2892  return;
2893  }
2894 
2895  // If any of our bases need a vtordisp for this type, so do we. Check our
2896  // direct bases for vtordisp requirements.
2897  for (const CXXBaseSpecifier &Base : RD->bases()) {
2898  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2899  const ASTRecordLayout &Layout = Context.getASTRecordLayout(BaseDecl);
2900  for (const auto &bi : Layout.getVBaseOffsetsMap())
2901  if (bi.second.hasVtorDisp())
2902  HasVtordispSet.insert(bi.first);
2903  }
2904  // We don't introduce any additional vtordisps if either:
2905  // * A user declared constructor or destructor aren't declared.
2906  // * #pragma vtordisp(0) or the /vd0 flag are in use.
2907  if ((!RD->hasUserDeclaredConstructor() && !RD->hasUserDeclaredDestructor()) ||
2908  RD->getMSVtorDispMode() == MSVtorDispAttr::Never)
2909  return;
2910  // /vd1 or #pragma vtordisp(1): Try to guess based on whether we think it's
2911  // possible for a partially constructed object with virtual base overrides to
2912  // escape a non-trivial constructor.
2913  assert(RD->getMSVtorDispMode() == MSVtorDispAttr::ForVBaseOverride);
2914  // Compute a set of base classes which define methods we override. A virtual
2915  // base in this set will require a vtordisp. A virtual base that transitively
2916  // contains one of these bases as a non-virtual base will also require a
2917  // vtordisp.
2918  llvm::SmallPtrSet<const CXXMethodDecl *, 8> Work;
2919  llvm::SmallPtrSet<const CXXRecordDecl *, 2> BasesWithOverriddenMethods;
2920  // Seed the working set with our non-destructor, non-pure virtual methods.
2921  for (const CXXMethodDecl *MD : RD->methods())
2922  if (MD->isVirtual() && !isa<CXXDestructorDecl>(MD) && !MD->isPure())
2923  Work.insert(MD);
2924  while (!Work.empty()) {
2925  const CXXMethodDecl *MD = *Work.begin();
2926  auto MethodRange = MD->overridden_methods();
2927  // If a virtual method has no-overrides it lives in its parent's vtable.
2928  if (MethodRange.begin() == MethodRange.end())
2929  BasesWithOverriddenMethods.insert(MD->getParent());
2930  else
2931  Work.insert(MethodRange.begin(), MethodRange.end());
2932  // We've finished processing this element, remove it from the working set.
2933  Work.erase(MD);
2934  }
2935  // For each of our virtual bases, check if it is in the set of overridden
2936  // bases or if it transitively contains a non-virtual base that is.
2937  for (const CXXBaseSpecifier &Base : RD->vbases()) {
2938  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2939  if (!HasVtordispSet.count(BaseDecl) &&
2940  RequiresVtordisp(BasesWithOverriddenMethods, BaseDecl))
2941  HasVtordispSet.insert(BaseDecl);
2942  }
2943 }
2944 
2945 /// getASTRecordLayout - Get or compute information about the layout of the
2946 /// specified record (struct/union/class), which indicates its size and field
2947 /// position information.
2948 const ASTRecordLayout &
2950  // These asserts test different things. A record has a definition
2951  // as soon as we begin to parse the definition. That definition is
2952  // not a complete definition (which is what isDefinition() tests)
2953  // until we *finish* parsing the definition.
2954 
2955  if (D->hasExternalLexicalStorage() && !D->getDefinition())
2956  getExternalSource()->CompleteType(const_cast<RecordDecl*>(D));
2957 
2958  D = D->getDefinition();
2959  assert(D && "Cannot get layout of forward declarations!");
2960  assert(!D->isInvalidDecl() && "Cannot get layout of invalid decl!");
2961  assert(D->isCompleteDefinition() && "Cannot layout type before complete!");
2962 
2963  // Look up this layout, if already laid out, return what we have.
2964  // Note that we can't save a reference to the entry because this function
2965  // is recursive.
2966  const ASTRecordLayout *Entry = ASTRecordLayouts[D];
2967  if (Entry) return *Entry;
2968 
2969  const ASTRecordLayout *NewEntry = nullptr;
2970 
2971  if (isMsLayout(*this)) {
2972  MicrosoftRecordLayoutBuilder Builder(*this);
2973  if (const auto *RD = dyn_cast<CXXRecordDecl>(D)) {
2974  Builder.cxxLayout(RD);
2975  NewEntry = new (*this) ASTRecordLayout(
2976  *this, Builder.Size, Builder.Alignment, Builder.RequiredAlignment,
2977  Builder.HasOwnVFPtr, Builder.HasOwnVFPtr || Builder.PrimaryBase,
2978  Builder.VBPtrOffset, Builder.DataSize, Builder.FieldOffsets,
2979  Builder.NonVirtualSize, Builder.Alignment, CharUnits::Zero(),
2980  Builder.PrimaryBase, false, Builder.SharedVBPtrBase,
2981  Builder.EndsWithZeroSizedObject, Builder.LeadsWithZeroSizedBase,
2982  Builder.Bases, Builder.VBases);
2983  } else {
2984  Builder.layout(D);
2985  NewEntry = new (*this) ASTRecordLayout(
2986  *this, Builder.Size, Builder.Alignment, Builder.RequiredAlignment,
2987  Builder.Size, Builder.FieldOffsets);
2988  }
2989  } else {
2990  if (const auto *RD = dyn_cast<CXXRecordDecl>(D)) {
2991  EmptySubobjectMap EmptySubobjects(*this, RD);
2992  ItaniumRecordLayoutBuilder Builder(*this, &EmptySubobjects);
2993  Builder.Layout(RD);
2994 
2995  // In certain situations, we are allowed to lay out objects in the
2996  // tail-padding of base classes. This is ABI-dependent.
2997  // FIXME: this should be stored in the record layout.
2998  bool skipTailPadding =
2999  mustSkipTailPadding(getTargetInfo().getCXXABI(), RD);
3000 
3001  // FIXME: This should be done in FinalizeLayout.
3002  CharUnits DataSize =
3003  skipTailPadding ? Builder.getSize() : Builder.getDataSize();
3004  CharUnits NonVirtualSize =
3005  skipTailPadding ? DataSize : Builder.NonVirtualSize;
3006  NewEntry = new (*this) ASTRecordLayout(
3007  *this, Builder.getSize(), Builder.Alignment,
3008  /*RequiredAlignment : used by MS-ABI)*/
3009  Builder.Alignment, Builder.HasOwnVFPtr, RD->isDynamicClass(),
3010  CharUnits::fromQuantity(-1), DataSize, Builder.FieldOffsets,
3011  NonVirtualSize, Builder.NonVirtualAlignment,
3012  EmptySubobjects.SizeOfLargestEmptySubobject, Builder.PrimaryBase,
3013  Builder.PrimaryBaseIsVirtual, nullptr, false, false, Builder.Bases,
3014  Builder.VBases);
3015  } else {
3016  ItaniumRecordLayoutBuilder Builder(*this, /*EmptySubobjects=*/nullptr);
3017  Builder.Layout(D);
3018 
3019  NewEntry = new (*this) ASTRecordLayout(
3020  *this, Builder.getSize(), Builder.Alignment,
3021  /*RequiredAlignment : used by MS-ABI)*/
3022  Builder.Alignment, Builder.getSize(), Builder.FieldOffsets);
3023  }
3024  }
3025 
3026  ASTRecordLayouts[D] = NewEntry;
3027 
3028  if (getLangOpts().DumpRecordLayouts) {
3029  llvm::outs() << "\n*** Dumping AST Record Layout\n";
3030  DumpRecordLayout(D, llvm::outs(), getLangOpts().DumpRecordLayoutsSimple);
3031  }
3032 
3033  return *NewEntry;
3034 }
3035 
3037  if (!getTargetInfo().getCXXABI().hasKeyFunctions())
3038  return nullptr;
3039 
3040  assert(RD->getDefinition() && "Cannot get key function for forward decl!");
3041  RD = RD->getDefinition();
3042 
3043  // Beware:
3044  // 1) computing the key function might trigger deserialization, which might
3045  // invalidate iterators into KeyFunctions
3046  // 2) 'get' on the LazyDeclPtr might also trigger deserialization and
3047  // invalidate the LazyDeclPtr within the map itself
3048  LazyDeclPtr Entry = KeyFunctions[RD];
3049  const Decl *Result =
3050  Entry ? Entry.get(getExternalSource()) : computeKeyFunction(*this, RD);
3051 
3052  // Store it back if it changed.
3053  if (Entry.isOffset() || Entry.isValid() != bool(Result))
3054  KeyFunctions[RD] = const_cast<Decl*>(Result);
3055 
3056  return cast_or_null<CXXMethodDecl>(Result);
3057 }
3058 
3060  assert(Method == Method->getFirstDecl() &&
3061  "not working with method declaration from class definition");
3062 
3063  // Look up the cache entry. Since we're working with the first
3064  // declaration, its parent must be the class definition, which is
3065  // the correct key for the KeyFunctions hash.
3066  const auto &Map = KeyFunctions;
3067  auto I = Map.find(Method->getParent());
3068 
3069  // If it's not cached, there's nothing to do.
3070  if (I == Map.end()) return;
3071 
3072  // If it is cached, check whether it's the target method, and if so,
3073  // remove it from the cache. Note, the call to 'get' might invalidate
3074  // the iterator and the LazyDeclPtr object within the map.
3075  LazyDeclPtr Ptr = I->second;
3076  if (Ptr.get(getExternalSource()) == Method) {
3077  // FIXME: remember that we did this for module / chained PCH state?
3078  KeyFunctions.erase(Method->getParent());
3079  }
3080 }
3081 
3082 static uint64_t getFieldOffset(const ASTContext &C, const FieldDecl *FD) {
3083  const ASTRecordLayout &Layout = C.getASTRecordLayout(FD->getParent());
3084  return Layout.getFieldOffset(FD->getFieldIndex());
3085 }
3086 
3087 uint64_t ASTContext::getFieldOffset(const ValueDecl *VD) const {
3088  uint64_t OffsetInBits;
3089  if (const FieldDecl *FD = dyn_cast<FieldDecl>(VD)) {
3090  OffsetInBits = ::getFieldOffset(*this, FD);
3091  } else {
3092  const IndirectFieldDecl *IFD = cast<IndirectFieldDecl>(VD);
3093 
3094  OffsetInBits = 0;
3095  for (const NamedDecl *ND : IFD->chain())
3096  OffsetInBits += ::getFieldOffset(*this, cast<FieldDecl>(ND));
3097  }
3098 
3099  return OffsetInBits;
3100 }
3101 
3103  const ObjCImplementationDecl *ID,
3104  const ObjCIvarDecl *Ivar) const {
3105  const ObjCInterfaceDecl *Container = Ivar->getContainingInterface();
3106 
3107  // FIXME: We should eliminate the need to have ObjCImplementationDecl passed
3108  // in here; it should never be necessary because that should be the lexical
3109  // decl context for the ivar.
3110 
3111  // If we know have an implementation (and the ivar is in it) then
3112  // look up in the implementation layout.
3113  const ASTRecordLayout *RL;
3114  if (ID && declaresSameEntity(ID->getClassInterface(), Container))
3115  RL = &getASTObjCImplementationLayout(ID);
3116  else
3117  RL = &getASTObjCInterfaceLayout(Container);
3118 
3119  // Compute field index.
3120  //
3121  // FIXME: The index here is closely tied to how ASTContext::getObjCLayout is
3122  // implemented. This should be fixed to get the information from the layout
3123  // directly.
3124  unsigned Index = 0;
3125 
3126  for (const ObjCIvarDecl *IVD = Container->all_declared_ivar_begin();
3127  IVD; IVD = IVD->getNextIvar()) {
3128  if (Ivar == IVD)
3129  break;
3130  ++Index;
3131  }
3132  assert(Index < RL->getFieldCount() && "Ivar is not inside record layout!");
3133 
3134  return RL->getFieldOffset(Index);
3135 }
3136 
3137 /// getObjCLayout - Get or compute information about the layout of the
3138 /// given interface.
3139 ///
3140 /// \param Impl - If given, also include the layout of the interface's
3141 /// implementation. This may differ by including synthesized ivars.
3142 const ASTRecordLayout &
3143 ASTContext::getObjCLayout(const ObjCInterfaceDecl *D,
3144  const ObjCImplementationDecl *Impl) const {
3145  // Retrieve the definition
3146  if (D->hasExternalLexicalStorage() && !D->getDefinition())
3147  getExternalSource()->CompleteType(const_cast<ObjCInterfaceDecl*>(D));
3148  D = D->getDefinition();
3149  assert(D && D->isThisDeclarationADefinition() && "Invalid interface decl!");
3150 
3151  // Look up this layout, if already laid out, return what we have.
3152  const ObjCContainerDecl *Key =
3153  Impl ? (const ObjCContainerDecl*) Impl : (const ObjCContainerDecl*) D;
3154  if (const ASTRecordLayout *Entry = ObjCLayouts[Key])
3155  return *Entry;
3156 
3157  // Add in synthesized ivar count if laying out an implementation.
3158  if (Impl) {
3159  unsigned SynthCount = CountNonClassIvars(D);
3160  // If there aren't any synthesized ivars then reuse the interface
3161  // entry. Note we can't cache this because we simply free all
3162  // entries later; however we shouldn't look up implementations
3163  // frequently.
3164  if (SynthCount == 0)
3165  return getObjCLayout(D, nullptr);
3166  }
3167 
3168  ItaniumRecordLayoutBuilder Builder(*this, /*EmptySubobjects=*/nullptr);
3169  Builder.Layout(D);
3170 
3171  const ASTRecordLayout *NewEntry =
3172  new (*this) ASTRecordLayout(*this, Builder.getSize(),
3173  Builder.Alignment,
3174  /*RequiredAlignment : used by MS-ABI)*/
3175  Builder.Alignment,
3176  Builder.getDataSize(),
3177  Builder.FieldOffsets);
3178 
3179  ObjCLayouts[Key] = NewEntry;
3180 
3181  return *NewEntry;
3182 }
3183 
3184 static void PrintOffset(raw_ostream &OS,
3185  CharUnits Offset, unsigned IndentLevel) {
3186  OS << llvm::format("%10" PRId64 " | ", (int64_t)Offset.getQuantity());
3187  OS.indent(IndentLevel * 2);
3188 }
3189 
3190 static void PrintBitFieldOffset(raw_ostream &OS, CharUnits Offset,
3191  unsigned Begin, unsigned Width,
3192  unsigned IndentLevel) {
3193  llvm::SmallString<10> Buffer;
3194  {
3195  llvm::raw_svector_ostream BufferOS(Buffer);
3196  BufferOS << Offset.getQuantity() << ':';
3197  if (Width == 0) {
3198  BufferOS << '-';
3199  } else {
3200  BufferOS << Begin << '-' << (Begin + Width - 1);
3201  }
3202  }
3203 
3204  OS << llvm::right_justify(Buffer, 10) << " | ";
3205  OS.indent(IndentLevel * 2);
3206 }
3207 
3208 static void PrintIndentNoOffset(raw_ostream &OS, unsigned IndentLevel) {
3209  OS << " | ";
3210  OS.indent(IndentLevel * 2);
3211 }
3212 
3213 static void DumpRecordLayout(raw_ostream &OS, const RecordDecl *RD,
3214  const ASTContext &C,
3215  CharUnits Offset,
3216  unsigned IndentLevel,
3217  const char* Description,
3218  bool PrintSizeInfo,
3219  bool IncludeVirtualBases) {
3220  const ASTRecordLayout &Layout = C.getASTRecordLayout(RD);
3221  auto CXXRD = dyn_cast<CXXRecordDecl>(RD);
3222 
3223  PrintOffset(OS, Offset, IndentLevel);
3224  OS << C.getTypeDeclType(const_cast<RecordDecl*>(RD)).getAsString();
3225  if (Description)
3226  OS << ' ' << Description;
3227  if (CXXRD && CXXRD->isEmpty())
3228  OS << " (empty)";
3229  OS << '\n';
3230 
3231  IndentLevel++;
3232 
3233  // Dump bases.
3234  if (CXXRD) {
3235  const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
3236  bool HasOwnVFPtr = Layout.hasOwnVFPtr();
3237  bool HasOwnVBPtr = Layout.hasOwnVBPtr();
3238 
3239  // Vtable pointer.
3240  if (CXXRD->isDynamicClass() && !PrimaryBase && !isMsLayout(C)) {
3241  PrintOffset(OS, Offset, IndentLevel);
3242  OS << '(' << *RD << " vtable pointer)\n";
3243  } else if (HasOwnVFPtr) {
3244  PrintOffset(OS, Offset, IndentLevel);
3245  // vfptr (for Microsoft C++ ABI)
3246  OS << '(' << *RD << " vftable pointer)\n";
3247  }
3248 
3249  // Collect nvbases.
3251  for (const CXXBaseSpecifier &Base : CXXRD->bases()) {
3252  assert(!Base.getType()->isDependentType() &&
3253  "Cannot layout class with dependent bases.");
3254  if (!Base.isVirtual())
3255  Bases.push_back(Base.getType()->getAsCXXRecordDecl());
3256  }
3257 
3258  // Sort nvbases by offset.
3259  std::stable_sort(Bases.begin(), Bases.end(),
3260  [&](const CXXRecordDecl *L, const CXXRecordDecl *R) {
3261  return Layout.getBaseClassOffset(L) < Layout.getBaseClassOffset(R);
3262  });
3263 
3264  // Dump (non-virtual) bases
3265  for (const CXXRecordDecl *Base : Bases) {
3266  CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base);
3267  DumpRecordLayout(OS, Base, C, BaseOffset, IndentLevel,
3268  Base == PrimaryBase ? "(primary base)" : "(base)",
3269  /*PrintSizeInfo=*/false,
3270  /*IncludeVirtualBases=*/false);
3271  }
3272 
3273  // vbptr (for Microsoft C++ ABI)
3274  if (HasOwnVBPtr) {
3275  PrintOffset(OS, Offset + Layout.getVBPtrOffset(), IndentLevel);
3276  OS << '(' << *RD << " vbtable pointer)\n";
3277  }
3278  }
3279 
3280  // Dump fields.
3281  uint64_t FieldNo = 0;
3282  for (RecordDecl::field_iterator I = RD->field_begin(),
3283  E = RD->field_end(); I != E; ++I, ++FieldNo) {
3284  const FieldDecl &Field = **I;
3285  uint64_t LocalFieldOffsetInBits = Layout.getFieldOffset(FieldNo);
3286  CharUnits FieldOffset =
3287  Offset + C.toCharUnitsFromBits(LocalFieldOffsetInBits);
3288 
3289  // Recursively dump fields of record type.
3290  if (auto RT = Field.getType()->getAs<RecordType>()) {
3291  DumpRecordLayout(OS, RT->getDecl(), C, FieldOffset, IndentLevel,
3292  Field.getName().data(),
3293  /*PrintSizeInfo=*/false,
3294  /*IncludeVirtualBases=*/true);
3295  continue;
3296  }
3297 
3298  if (Field.isBitField()) {
3299  uint64_t LocalFieldByteOffsetInBits = C.toBits(FieldOffset - Offset);
3300  unsigned Begin = LocalFieldOffsetInBits - LocalFieldByteOffsetInBits;
3301  unsigned Width = Field.getBitWidthValue(C);
3302  PrintBitFieldOffset(OS, FieldOffset, Begin, Width, IndentLevel);
3303  } else {
3304  PrintOffset(OS, FieldOffset, IndentLevel);
3305  }
3306  OS << Field.getType().getAsString() << ' ' << Field << '\n';
3307  }
3308 
3309  // Dump virtual bases.
3310  if (CXXRD && IncludeVirtualBases) {
3311  const ASTRecordLayout::VBaseOffsetsMapTy &VtorDisps =
3312  Layout.getVBaseOffsetsMap();
3313 
3314  for (const CXXBaseSpecifier &Base : CXXRD->vbases()) {
3315  assert(Base.isVirtual() && "Found non-virtual class!");
3316  const CXXRecordDecl *VBase = Base.getType()->getAsCXXRecordDecl();
3317 
3318  CharUnits VBaseOffset = Offset + Layout.getVBaseClassOffset(VBase);
3319 
3320  if (VtorDisps.find(VBase)->second.hasVtorDisp()) {
3321  PrintOffset(OS, VBaseOffset - CharUnits::fromQuantity(4), IndentLevel);
3322  OS << "(vtordisp for vbase " << *VBase << ")\n";
3323  }
3324 
3325  DumpRecordLayout(OS, VBase, C, VBaseOffset, IndentLevel,
3326  VBase == Layout.getPrimaryBase() ?
3327  "(primary virtual base)" : "(virtual base)",
3328  /*PrintSizeInfo=*/false,
3329  /*IncludeVirtualBases=*/false);
3330  }
3331  }
3332 
3333  if (!PrintSizeInfo) return;
3334 
3335  PrintIndentNoOffset(OS, IndentLevel - 1);
3336  OS << "[sizeof=" << Layout.getSize().getQuantity();
3337  if (CXXRD && !isMsLayout(C))
3338  OS << ", dsize=" << Layout.getDataSize().getQuantity();
3339  OS << ", align=" << Layout.getAlignment().getQuantity();
3340 
3341  if (CXXRD) {
3342  OS << ",\n";
3343  PrintIndentNoOffset(OS, IndentLevel - 1);
3344  OS << " nvsize=" << Layout.getNonVirtualSize().getQuantity();
3345  OS << ", nvalign=" << Layout.getNonVirtualAlignment().getQuantity();
3346  }
3347  OS << "]\n";
3348 }
3349 
3351  raw_ostream &OS,
3352  bool Simple) const {
3353  if (!Simple) {
3354  ::DumpRecordLayout(OS, RD, *this, CharUnits(), 0, nullptr,
3355  /*PrintSizeInfo*/true,
3356  /*IncludeVirtualBases=*/true);
3357  return;
3358  }
3359 
3360  // The "simple" format is designed to be parsed by the
3361  // layout-override testing code. There shouldn't be any external
3362  // uses of this format --- when LLDB overrides a layout, it sets up
3363  // the data structures directly --- so feel free to adjust this as
3364  // you like as long as you also update the rudimentary parser for it
3365  // in libFrontend.
3366 
3367  const ASTRecordLayout &Info = getASTRecordLayout(RD);
3368  OS << "Type: " << getTypeDeclType(RD).getAsString() << "\n";
3369  OS << "\nLayout: ";
3370  OS << "<ASTRecordLayout\n";
3371  OS << " Size:" << toBits(Info.getSize()) << "\n";
3372  if (!isMsLayout(*this))
3373  OS << " DataSize:" << toBits(Info.getDataSize()) << "\n";
3374  OS << " Alignment:" << toBits(Info.getAlignment()) << "\n";
3375  OS << " FieldOffsets: [";
3376  for (unsigned i = 0, e = Info.getFieldCount(); i != e; ++i) {
3377  if (i) OS << ", ";
3378  OS << Info.getFieldOffset(i);
3379  }
3380  OS << "]>\n";
3381 }
static uint64_t getFieldOffset(const ASTContext &C, const FieldDecl *FD)
Defines the clang::ASTContext interface.
CharUnits alignTo(const CharUnits &Align) const
alignTo - Returns the next integer (mod 2**64) that is greater than or equal to this quantity and is ...
Definition: CharUnits.h:184
Represents a function declaration or definition.
Definition: Decl.h:1709
Only allocate objects in the tail padding of a base class if the base class is not POD according to t...
Definition: TargetCXXABI.h:302
static DiagnosticBuilder Diag(DiagnosticsEngine *Diags, const LangOptions &Features, FullSourceLoc TokLoc, const char *TokBegin, const char *TokRangeBegin, const char *TokRangeEnd, unsigned DiagID)
Produce a diagnostic highlighting some portion of a literal.
bool isPrimaryBaseVirtual() const
isPrimaryBaseVirtual - Get whether the primary base for this record is virtual or not...
Definition: RecordLayout.h:216
A (possibly-)qualified type.
Definition: Type.h:653
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:796
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:1549
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:460
const llvm::Triple & getTriple() const
Returns the target triple of the primary target.
Definition: TargetInfo.h:795
CharUnits getBaseClassOffset(const CXXRecordDecl *Base) const
getBaseClassOffset - Get the offset, in chars, for the given base class.
Definition: RecordLayout.h:223
unsigned getNumVBases() const
Retrieves the number of virtual base classes of this class.
Definition: DeclCXX.h:811
Decl - This represents one declaration (or definition), e.g.
Definition: DeclBase.h:86
bool isPOD() const
Whether this class is a POD-type (C++ [class]p4)
Definition: DeclCXX.h:1287
unsigned getFieldIndex() const
Returns the index of this field within its record, as appropriate for passing to ASTRecordLayout::get...
Definition: Decl.cpp:3708
const RecordDecl * getParent() const
Returns the parent of this field declaration, which is the struct in which this field is defined...
Definition: Decl.h:2700
The base class of the type hierarchy.
Definition: Type.h:1419
DiagnosticsEngine & getDiagnostics() const
DiagnosticBuilder Report(SourceLocation Loc, unsigned DiagID)
Issue the message to the client.
Definition: Diagnostic.h:1294
Represents an array type, per C99 6.7.5.2 - Array Declarators.
Definition: Type.h:2627
bool isZero() const
isZero - Test whether the quantity equals zero.
Definition: CharUnits.h:116
const TargetInfo & getTargetInfo() const
Definition: ASTContext.h:671
CharUnits getAlignment() const
getAlignment - Get the record alignment in characters.
Definition: RecordLayout.h:171
unsigned getCharWidth() const
Definition: TargetInfo.h:335
QualType getElementType() const
Definition: Type.h:2662
bool isCompleteDefinition() const
Return true if this decl has its body fully specified.
Definition: Decl.h:3152
bool hasVBPtr() const
hasVBPtr - Does this class have a virtual function table pointer.
Definition: RecordLayout.h:276
const T * getAs() const
Member-template getAs<specific type>&#39;.
Definition: Type.h:6390
unsigned getCharAlign() const
Definition: TargetInfo.h:336
The "__interface" keyword.
Definition: Type.h:4770
bool hasOwnVFPtr() const
hasOwnVFPtr - Does this class provide its own virtual-function table pointer, rather than inheriting ...
Definition: RecordLayout.h:250
bool isInvalidDecl() const
Definition: DeclBase.h:546
unsigned getZeroLengthBitfieldBoundary() const
Get the fixed alignment value in bits for a member that follows a zero length bitfield.
Definition: TargetInfo.h:524
bool mayInsertExtraPadding(bool EmitRemark=false) const
Whether we are allowed to insert extra padding between fields.
Definition: Decl.cpp:4057
IdentifierInfo * getIdentifier() const
Get the identifier that names this declaration, if there is one.
Definition: Decl.h:269
Represents a struct/union/class.
Definition: Decl.h:3543
uint64_t getPointerWidth(unsigned AddrSpace) const
Return the width of pointers on this target, for the specified address space.
Definition: TargetInfo.h:313
bool isEmpty() const
Determine whether this is an empty class in the sense of (C++11 [meta.unary.prop]).
Definition: DeclCXX.h:1302
TargetCXXABI getCXXABI() const
Get the C++ ABI currently in use.
Definition: TargetInfo.h:864
Holds long-lived AST nodes (such as types and decls) that can be referred to throughout the semantic ...
Definition: ASTContext.h:149
RecordDecl * getDefinition() const
Returns the RecordDecl that actually defines this struct/union/class.
Definition: Decl.h:3751
field_range fields() const
Definition: Decl.h:3761
Represents a member of a struct/union/class.
Definition: Decl.h:2516
bool hasUserDeclaredDestructor() const
Determine whether this class has a user-declared destructor.
Definition: DeclCXX.h:1158
static CharUnits Zero()
Zero - Construct a CharUnits quantity of zero.
Definition: CharUnits.h:53
CharUnits getVBaseClassOffset(const CXXRecordDecl *VBase) const
getVBaseClassOffset - Get the offset, in chars, for the given base class.
Definition: RecordLayout.h:231
method_iterator method_begin() const
Method begin iterator.
Definition: DeclCXX.h:844
uint64_t lookupFieldBitOffset(const ObjCInterfaceDecl *OID, const ObjCImplementationDecl *ID, const ObjCIvarDecl *Ivar) const
Get the offset of an ObjCIvarDecl in bits.
const ASTRecordLayout & getASTObjCInterfaceLayout(const ObjCInterfaceDecl *D) const
Get or compute information about the layout of the specified Objective-C interface.
specific_decl_iterator< FieldDecl > field_iterator
Definition: Decl.h:3758
bool canKeyFunctionBeInline() const
Can an out-of-line inline function serve as a key function?
Definition: TargetCXXABI.h:259
uint64_t getConstantArrayElementCount(const ConstantArrayType *CA) const
Return number of constant array elements.
bool isBitField() const
Determines whether this field is a bitfield.
Definition: Decl.h:2594
ObjCContainerDecl - Represents a container for method declarations.
Definition: DeclObjC.h:986
TagKind getTagKind() const
Definition: Decl.h:3211
CharUnits - This is an opaque type for sizes expressed in character units.
Definition: CharUnits.h:38
uint32_t Offset
Definition: CacheTokens.cpp:43
bool endsWithZeroSizedObject() const
Definition: RecordLayout.h:285
ArrayRef< NamedDecl * > chain() const
Definition: Decl.h:2784
unsigned Align
Definition: ASTContext.h:139
field_iterator field_begin() const
Definition: Decl.cpp:4010
unsigned getBitWidthValue(const ASTContext &Ctx) const
Definition: Decl.cpp:3698
bool declaresSameEntity(const Decl *D1, const Decl *D2)
Determine whether two declarations declare the same entity.
Definition: DeclBase.h:1153
const VBaseOffsetsMapTy & getVBaseOffsetsMap() const
Definition: RecordLayout.h:306
bool isAlignmentRequired(const Type *T) const
Determine if the alignment the type has was required using an alignment attribute.
bool useZeroLengthBitfieldAlignment() const
Check whether zero length bitfields should force alignment of the next member.
Definition: TargetInfo.h:518
Represents an ObjC class declaration.
Definition: DeclObjC.h:1191
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:380
CanQualType UnsignedCharTy
Definition: ASTContext.h:1005
lookup_result lookup(DeclarationName Name) const
lookup - Find the declarations (if any) with the given Name in this context.
Definition: DeclBase.cpp:1531
bool hasAttr() const
Definition: DeclBase.h:535
static CharUnits One()
One - Construct a CharUnits quantity of one.
Definition: CharUnits.h:58
A little helper class used to produce diagnostics.
Definition: Diagnostic.h:1042
CXXRecordDecl * getAsCXXRecordDecl() const
Retrieves the CXXRecordDecl that this type refers to, either because the type is a RecordType or beca...
Definition: Type.cpp:1590
bool isDynamicClass() const
Definition: DeclCXX.h:774
bool useExplicitBitFieldAlignment() const
Check whether explicit bitfield alignment attributes should be.
Definition: TargetInfo.h:530
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:1585
QuantityType getQuantity() const
getQuantity - Get the raw integer representation of this quantity.
Definition: CharUnits.h:179
ASTRecordLayout - This class contains layout information for one RecordDecl, which is a struct/union/...
Definition: RecordLayout.h:39
bool isMsStruct(const ASTContext &C) const
Get whether or not this is an ms_struct which can be turned on with an attribute, pragma...
Definition: Decl.cpp:4027
bool isInlineSpecified() const
Determine whether the "inline" keyword was specified for this function.
Definition: Decl.h:2291
Represent the declaration of a variable (in which case it is an lvalue) a function (in which case it ...
Definition: Decl.h:636
SourceLocation End
const FunctionProtoType * T
bool isNearlyEmpty(const CXXRecordDecl *RD) const
field_iterator field_end() const
Definition: Decl.h:3764
#define bool
Definition: stdbool.h:31
CharUnits getSizeOfLargestEmptySubobject() const
Definition: RecordLayout.h:238
overridden_method_range overridden_methods() const
Definition: DeclCXX.cpp:2124
CharUnits getTypeAlignInChars(QualType T) const
Return the ABI-specified alignment of a (complete) type T, in characters.
CXXRecordDecl * getDefinition() const
Definition: DeclCXX.h:754
ObjCInterfaceDecl * getSuperClass() const
Definition: DeclObjC.cpp:331
SourceLocation Begin
const CXXRecordDecl * getPrimaryBase() const
getPrimaryBase - Get the primary base for this record.
Definition: RecordLayout.h:208
static CharUnits fromQuantity(QuantityType Quantity)
fromQuantity - Construct a CharUnits quantity from a raw integer type.
Definition: CharUnits.h:63
unsigned getFieldCount() const
getFieldCount - Get the number of fields in the layout.
Definition: RecordLayout.h:177
bool isTrivial() const
Determine whether this class is considered trivial.
Definition: DeclCXX.h:1520
bool isPolymorphic() const
Whether this class is polymorphic (C++ [class.virtual]), which means that the class contains or inher...
Definition: DeclCXX.h:1312
bool hasExtendableVFPtr() const
hasVFPtr - Does this class have a virtual function table pointer that can be extended by a derived cl...
Definition: RecordLayout.h:258
unsigned getMaxAlignment() const
getMaxAlignment - return the maximum alignment specified by attributes on this decl, 0 if there are none.
Definition: DeclBase.cpp:384
method_iterator method_end() const
Method past-the-end iterator.
Definition: DeclCXX.h:849
CharUnits getVBPtrOffset() const
getVBPtrOffset - Get the offset for virtual base table pointer.
Definition: RecordLayout.h:296
const Type * getBaseElementTypeUnsafe() const
Get the base element type of this type, potentially discarding type qualifiers.
Definition: Type.h:6348
CharUnits getRequiredAlignment() const
Definition: RecordLayout.h:281
QualType getTypeDeclType(const TypeDecl *Decl, const TypeDecl *PrevDecl=nullptr) const
Return the unique reference to the type for the specified type declaration.
Definition: ASTContext.h:1358
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:718
decl_type * getFirstDecl()
Return the first declaration of this declaration or itself if this is the only declaration.
Definition: Redeclarable.h:220
static bool recordUsesEBO(const RecordDecl *RD)
RecordDecl * getDecl() const
Definition: Type.h:4064
Abstract interface for external sources of AST nodes.
uint64_t getFieldOffset(unsigned FieldNo) const
getFieldOffset - Get the offset of the given field index, in bits.
Definition: RecordLayout.h:181
static uint64_t roundUpSizeToCharAlignment(uint64_t Size, const ASTContext &Context)
#define false
Definition: stdbool.h:33
The "struct" keyword.
Definition: Type.h:4767
Only allocate objects in the tail padding of a base class if the base class is not POD according to t...
Definition: TargetCXXABI.h:306
Encodes a location in the source.
A set of all the primary bases for a class.
static void PrintIndentNoOffset(raw_ostream &OS, unsigned IndentLevel)
QualType getBaseElementType(const ArrayType *VAT) const
Return the innermost element type of an array type.
Represents a static or instance method of a struct/union/class.
Definition: DeclCXX.h:2016
const ConstantArrayType * getAsConstantArrayType(QualType T) const
Definition: ASTContext.h:2336
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:1891
This template specialization was instantiated from a template due to an explicit instantiation defini...
Definition: Specifiers.h:161
CharUnits getDataSize() const
getDataSize() - Get the record data size, which is the record size without tail padding, in characters.
Definition: RecordLayout.h:187
bool useBitFieldTypeAlignment() const
Check whether the alignment of bit-field types is respected when laying out structures.
Definition: TargetInfo.h:512
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:3636
bool isValid() const
Whether this pointer is non-NULL.
ASTContext & operator=(const ASTContext &)=delete
std::pair< CharUnits, CharUnits > getTypeInfoInChars(const Type *T) const
CanQualType UnsignedShortTy
Definition: ASTContext.h:1005
ObjCIvarDecl * getNextIvar()
Definition: DeclObjC.h:1997
CharUnits getNonVirtualAlignment() const
getNonVirtualSize - Get the non-virtual alignment (in chars) of an object, which is the alignment of ...
Definition: RecordLayout.h:201
TagTypeKind
The kind of a tag type.
Definition: Type.h:4765
const ObjCInterfaceDecl * getClassInterface() const
Definition: DeclObjC.h:2459
Dataflow Directional Tag Classes.
CharUnits getSize() const
getSize - Get the record size in characters.
Definition: RecordLayout.h:174
Represents a field injected from an anonymous union/struct into the parent scope. ...
Definition: Decl.h:2762
CanQualType UnsignedLongLongTy
Definition: ASTContext.h:1006
ObjCInterfaceDecl * getDefinition()
Retrieve the definition of this class, or NULL if this class has been forward-declared (with @class) ...
Definition: DeclObjC.h:1568
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:959
TailPaddingUseRules getTailPaddingUseRules() const
Definition: TargetCXXABI.h:308
bool isCXX11StandardLayout() const
Determine whether this class was standard-layout per C++11 [class]p7, specifically using the C++11 ru...
Definition: DeclCXX.h:1327
static std::string getAsString(SplitQualType split, const PrintingPolicy &Policy)
Definition: Type.h:979
const CXXRecordDecl * getParent() const
Returns the parent of this method declaration, which is the class in which this method is defined...
Definition: DeclCXX.h:2136
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:1744
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:1048
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:1600
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:2571
bool isIncompleteArrayType() const
Definition: Type.h:6078
A helper class that allows the use of isa/cast/dyncast to detect TagType objects of structs/unions/cl...
Definition: Type.h:4054
CanQualType UnsignedLongTy
Definition: ASTContext.h:1005
static bool RequiresVtordisp(const llvm::SmallPtrSetImpl< const CXXRecordDecl *> &BasesWithOverriddenMethods, const CXXRecordDecl *RD)
T * getAttr() const
Definition: DeclBase.h:531
uint64_t getCharWidth() const
Return the size of the character type, in bits.
Definition: ASTContext.h:2026
void setNonKeyFunction(const CXXMethodDecl *method)
Observe that the given method cannot be a key function.
Base for LValueReferenceType and RValueReferenceType.
Definition: Type.h:2488
The "class" keyword.
Definition: Type.h:4776
Represents a base class of a C++ class.
Definition: DeclCXX.h:192
uint64_t getTypeSize(QualType T) const
Return the size of the specified (complete) type T, in bits.
Definition: ASTContext.h:2022
uint64_t getFieldOffset(const ValueDecl *FD) const
Get the offset of a FieldDecl or IndirectFieldDecl, in bits.
CharUnits toCharUnitsFromBits(int64_t BitSize) const
Convert a size in bits to a size in characters.
Defines the C++ Decl subclasses, other than those for templates (found in DeclTemplate.h) and friends (in DeclFriend.h).
int64_t toBits(CharUnits CharSize) const
Convert a size in characters to a size in bits.
const CXXMethodDecl * getCurrentKeyFunction(const CXXRecordDecl *RD)
Get our current best idea for the key function of the given record decl, or nullptr if there isn&#39;t on...
Represents a C++ struct/union/class.
Definition: DeclCXX.h:300
TypeInfo getTypeInfo(const Type *T) const
Get the size and alignment of the specified complete type in bits.
ObjCIvarDecl - Represents an ObjC instance variable.
Definition: DeclObjC.h:1964
CharUnits getNonVirtualSize() const
getNonVirtualSize - Get the non-virtual size (in chars) of an object, which is the size of the object...
Definition: RecordLayout.h:193
static bool isMsLayout(const ASTContext &Context)
static unsigned getCharWidth(tok::TokenKind kind, const TargetInfo &Target)
This class is used for builtin types like &#39;int&#39;.
Definition: Type.h:2212
static const CXXMethodDecl * computeKeyFunction(ASTContext &Context, const CXXRecordDecl *RD)
The tail-padding of a base class is always theoretically available, even if it&#39;s POD.
Definition: TargetCXXABI.h:297
llvm::DenseMap< const CXXRecordDecl *, VBaseInfo > VBaseOffsetsMapTy
Definition: RecordLayout.h:60
bool isOffset() const
Whether this pointer is currently stored as an offset.
uint64_t getPointerAlign(unsigned AddrSpace) const
Definition: TargetInfo.h:316
Defines the clang::TargetInfo interface.
bool isMicrosoft() const
Is this ABI an MSVC-compatible ABI?
Definition: TargetCXXABI.h:154
StringRef getName() const
Get the name of identifier for this declaration as a StringRef.
Definition: Decl.h:275
static void PrintBitFieldOffset(raw_ostream &OS, CharUnits Offset, unsigned Begin, unsigned Width, unsigned IndentLevel)
uint64_t Width
Definition: ASTContext.h:138
__DEVICE__ int max(int __a, int __b)
bool isUnion() const
Definition: Decl.h:3220
__DEVICE__ int min(int __a, int __b)
CharUnits getTypeSizeInChars(QualType T) const
Return the size of the specified (complete) type T, in characters.
QualType getType() const
Definition: Decl.h:647
This represents a decl that may have a name.
Definition: Decl.h:248
ObjCIvarDecl * all_declared_ivar_begin()
all_declared_ivar_begin - return first ivar declared in this class, its extensions and its implementa...
Definition: DeclObjC.cpp:1546
bool hasOwnVBPtr() const
hasOwnVBPtr - Does this class provide its own virtual-base table pointer, rather than inheriting one ...
Definition: RecordLayout.h:270
unsigned getTargetAddressSpace(QualType T) const
Definition: ASTContext.h:2422
const LangOptions & getLangOpts() const
Definition: ASTContext.h:688
Represents the canonical version of C arrays with a specified constant size.
Definition: Type.h:2687
base_class_range vbases()
Definition: DeclCXX.h:813
SourceLocation getLocation() const
Definition: DeclBase.h:416
bool isExternallyVisible() const
Definition: Decl.h:379
CanQualType UnsignedIntTy
Definition: ASTContext.h:1005
bool leadsWithZeroSizedBase() const
Definition: RecordLayout.h:289
method_range methods() const
Definition: DeclCXX.h:838