clang  3.8.0
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  typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsetsMapTy;
636 
637  /// Bases - base classes and their offsets in the record.
638  BaseOffsetsMapTy Bases;
639 
640  // VBases - virtual base classes and their offsets in the record.
642 
643  /// IndirectPrimaryBases - Virtual base classes, direct or indirect, that are
644  /// primary base classes for some other direct or indirect base class.
645  CXXIndirectPrimaryBaseSet IndirectPrimaryBases;
646 
647  /// FirstNearlyEmptyVBase - The first nearly empty virtual base class in
648  /// inheritance graph order. Used for determining the primary base class.
649  const CXXRecordDecl *FirstNearlyEmptyVBase;
650 
651  /// VisitedVirtualBases - A set of all the visited virtual bases, used to
652  /// avoid visiting virtual bases more than once.
653  llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBases;
654 
655  /// Valid if UseExternalLayout is true.
656  ExternalLayout External;
657 
658  ItaniumRecordLayoutBuilder(const ASTContext &Context,
659  EmptySubobjectMap *EmptySubobjects)
660  : Context(Context), EmptySubobjects(EmptySubobjects), Size(0),
661  Alignment(CharUnits::One()), UnpackedAlignment(CharUnits::One()),
662  UseExternalLayout(false), InferAlignment(false), Packed(false),
663  IsUnion(false), IsMac68kAlign(false), IsMsStruct(false),
664  UnfilledBitsInLastUnit(0), LastBitfieldTypeSize(0),
665  MaxFieldAlignment(CharUnits::Zero()), DataSize(0),
666  NonVirtualSize(CharUnits::Zero()),
667  NonVirtualAlignment(CharUnits::One()), PrimaryBase(nullptr),
668  PrimaryBaseIsVirtual(false), HasOwnVFPtr(false),
669  FirstNearlyEmptyVBase(nullptr) {}
670 
671  void Layout(const RecordDecl *D);
672  void Layout(const CXXRecordDecl *D);
673  void Layout(const ObjCInterfaceDecl *D);
674 
675  void LayoutFields(const RecordDecl *D);
676  void LayoutField(const FieldDecl *D, bool InsertExtraPadding);
677  void LayoutWideBitField(uint64_t FieldSize, uint64_t TypeSize,
678  bool FieldPacked, const FieldDecl *D);
679  void LayoutBitField(const FieldDecl *D);
680 
681  TargetCXXABI getCXXABI() const {
682  return Context.getTargetInfo().getCXXABI();
683  }
684 
685  /// BaseSubobjectInfoAllocator - Allocator for BaseSubobjectInfo objects.
686  llvm::SpecificBumpPtrAllocator<BaseSubobjectInfo> BaseSubobjectInfoAllocator;
687 
688  typedef llvm::DenseMap<const CXXRecordDecl *, BaseSubobjectInfo *>
689  BaseSubobjectInfoMapTy;
690 
691  /// VirtualBaseInfo - Map from all the (direct or indirect) virtual bases
692  /// of the class we're laying out to their base subobject info.
693  BaseSubobjectInfoMapTy VirtualBaseInfo;
694 
695  /// NonVirtualBaseInfo - Map from all the direct non-virtual bases of the
696  /// class we're laying out to their base subobject info.
697  BaseSubobjectInfoMapTy NonVirtualBaseInfo;
698 
699  /// ComputeBaseSubobjectInfo - Compute the base subobject information for the
700  /// bases of the given class.
701  void ComputeBaseSubobjectInfo(const CXXRecordDecl *RD);
702 
703  /// ComputeBaseSubobjectInfo - Compute the base subobject information for a
704  /// single class and all of its base classes.
705  BaseSubobjectInfo *ComputeBaseSubobjectInfo(const CXXRecordDecl *RD,
706  bool IsVirtual,
707  BaseSubobjectInfo *Derived);
708 
709  /// DeterminePrimaryBase - Determine the primary base of the given class.
710  void DeterminePrimaryBase(const CXXRecordDecl *RD);
711 
712  void SelectPrimaryVBase(const CXXRecordDecl *RD);
713 
714  void EnsureVTablePointerAlignment(CharUnits UnpackedBaseAlign);
715 
716  /// LayoutNonVirtualBases - Determines the primary base class (if any) and
717  /// lays it out. Will then proceed to lay out all non-virtual base clasess.
718  void LayoutNonVirtualBases(const CXXRecordDecl *RD);
719 
720  /// LayoutNonVirtualBase - Lays out a single non-virtual base.
721  void LayoutNonVirtualBase(const BaseSubobjectInfo *Base);
722 
723  void AddPrimaryVirtualBaseOffsets(const BaseSubobjectInfo *Info,
724  CharUnits Offset);
725 
726  /// LayoutVirtualBases - Lays out all the virtual bases.
727  void LayoutVirtualBases(const CXXRecordDecl *RD,
728  const CXXRecordDecl *MostDerivedClass);
729 
730  /// LayoutVirtualBase - Lays out a single virtual base.
731  void LayoutVirtualBase(const BaseSubobjectInfo *Base);
732 
733  /// LayoutBase - Will lay out a base and return the offset where it was
734  /// placed, in chars.
735  CharUnits LayoutBase(const BaseSubobjectInfo *Base);
736 
737  /// InitializeLayout - Initialize record layout for the given record decl.
738  void InitializeLayout(const Decl *D);
739 
740  /// FinishLayout - Finalize record layout. Adjust record size based on the
741  /// alignment.
742  void FinishLayout(const NamedDecl *D);
743 
744  void UpdateAlignment(CharUnits NewAlignment, CharUnits UnpackedNewAlignment);
745  void UpdateAlignment(CharUnits NewAlignment) {
746  UpdateAlignment(NewAlignment, NewAlignment);
747  }
748 
749  /// \brief Retrieve the externally-supplied field offset for the given
750  /// field.
751  ///
752  /// \param Field The field whose offset is being queried.
753  /// \param ComputedOffset The offset that we've computed for this field.
754  uint64_t updateExternalFieldOffset(const FieldDecl *Field,
755  uint64_t ComputedOffset);
756 
757  void CheckFieldPadding(uint64_t Offset, uint64_t UnpaddedOffset,
758  uint64_t UnpackedOffset, unsigned UnpackedAlign,
759  bool isPacked, const FieldDecl *D);
760 
761  DiagnosticBuilder Diag(SourceLocation Loc, unsigned DiagID);
762 
763  CharUnits getSize() const {
764  assert(Size % Context.getCharWidth() == 0);
765  return Context.toCharUnitsFromBits(Size);
766  }
767  uint64_t getSizeInBits() const { return Size; }
768 
769  void setSize(CharUnits NewSize) { Size = Context.toBits(NewSize); }
770  void setSize(uint64_t NewSize) { Size = NewSize; }
771 
772  CharUnits getAligment() const { return Alignment; }
773 
774  CharUnits getDataSize() const {
775  assert(DataSize % Context.getCharWidth() == 0);
776  return Context.toCharUnitsFromBits(DataSize);
777  }
778  uint64_t getDataSizeInBits() const { return DataSize; }
779 
780  void setDataSize(CharUnits NewSize) { DataSize = Context.toBits(NewSize); }
781  void setDataSize(uint64_t NewSize) { DataSize = NewSize; }
782 
783  ItaniumRecordLayoutBuilder(const ItaniumRecordLayoutBuilder &) = delete;
784  void operator=(const ItaniumRecordLayoutBuilder &) = delete;
785 };
786 } // end anonymous namespace
787 
788 void ItaniumRecordLayoutBuilder::SelectPrimaryVBase(const CXXRecordDecl *RD) {
789  for (const auto &I : RD->bases()) {
790  assert(!I.getType()->isDependentType() &&
791  "Cannot layout class with dependent bases.");
792 
793  const CXXRecordDecl *Base = I.getType()->getAsCXXRecordDecl();
794 
795  // Check if this is a nearly empty virtual base.
796  if (I.isVirtual() && Context.isNearlyEmpty(Base)) {
797  // If it's not an indirect primary base, then we've found our primary
798  // base.
799  if (!IndirectPrimaryBases.count(Base)) {
800  PrimaryBase = Base;
801  PrimaryBaseIsVirtual = true;
802  return;
803  }
804 
805  // Is this the first nearly empty virtual base?
806  if (!FirstNearlyEmptyVBase)
807  FirstNearlyEmptyVBase = Base;
808  }
809 
810  SelectPrimaryVBase(Base);
811  if (PrimaryBase)
812  return;
813  }
814 }
815 
816 /// DeterminePrimaryBase - Determine the primary base of the given class.
817 void ItaniumRecordLayoutBuilder::DeterminePrimaryBase(const CXXRecordDecl *RD) {
818  // If the class isn't dynamic, it won't have a primary base.
819  if (!RD->isDynamicClass())
820  return;
821 
822  // Compute all the primary virtual bases for all of our direct and
823  // indirect bases, and record all their primary virtual base classes.
824  RD->getIndirectPrimaryBases(IndirectPrimaryBases);
825 
826  // If the record has a dynamic base class, attempt to choose a primary base
827  // class. It is the first (in direct base class order) non-virtual dynamic
828  // base class, if one exists.
829  for (const auto &I : RD->bases()) {
830  // Ignore virtual bases.
831  if (I.isVirtual())
832  continue;
833 
834  const CXXRecordDecl *Base = I.getType()->getAsCXXRecordDecl();
835 
836  if (Base->isDynamicClass()) {
837  // We found it.
838  PrimaryBase = Base;
839  PrimaryBaseIsVirtual = false;
840  return;
841  }
842  }
843 
844  // Under the Itanium ABI, if there is no non-virtual primary base class,
845  // try to compute the primary virtual base. The primary virtual base is
846  // the first nearly empty virtual base that is not an indirect primary
847  // virtual base class, if one exists.
848  if (RD->getNumVBases() != 0) {
849  SelectPrimaryVBase(RD);
850  if (PrimaryBase)
851  return;
852  }
853 
854  // Otherwise, it is the first indirect primary base class, if one exists.
855  if (FirstNearlyEmptyVBase) {
856  PrimaryBase = FirstNearlyEmptyVBase;
857  PrimaryBaseIsVirtual = true;
858  return;
859  }
860 
861  assert(!PrimaryBase && "Should not get here with a primary base!");
862 }
863 
864 BaseSubobjectInfo *ItaniumRecordLayoutBuilder::ComputeBaseSubobjectInfo(
865  const CXXRecordDecl *RD, bool IsVirtual, BaseSubobjectInfo *Derived) {
866  BaseSubobjectInfo *Info;
867 
868  if (IsVirtual) {
869  // Check if we already have info about this virtual base.
870  BaseSubobjectInfo *&InfoSlot = VirtualBaseInfo[RD];
871  if (InfoSlot) {
872  assert(InfoSlot->Class == RD && "Wrong class for virtual base info!");
873  return InfoSlot;
874  }
875 
876  // We don't, create it.
877  InfoSlot = new (BaseSubobjectInfoAllocator.Allocate()) BaseSubobjectInfo;
878  Info = InfoSlot;
879  } else {
880  Info = new (BaseSubobjectInfoAllocator.Allocate()) BaseSubobjectInfo;
881  }
882 
883  Info->Class = RD;
884  Info->IsVirtual = IsVirtual;
885  Info->Derived = nullptr;
886  Info->PrimaryVirtualBaseInfo = nullptr;
887 
888  const CXXRecordDecl *PrimaryVirtualBase = nullptr;
889  BaseSubobjectInfo *PrimaryVirtualBaseInfo = nullptr;
890 
891  // Check if this base has a primary virtual base.
892  if (RD->getNumVBases()) {
893  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
894  if (Layout.isPrimaryBaseVirtual()) {
895  // This base does have a primary virtual base.
896  PrimaryVirtualBase = Layout.getPrimaryBase();
897  assert(PrimaryVirtualBase && "Didn't have a primary virtual base!");
898 
899  // Now check if we have base subobject info about this primary base.
900  PrimaryVirtualBaseInfo = VirtualBaseInfo.lookup(PrimaryVirtualBase);
901 
902  if (PrimaryVirtualBaseInfo) {
903  if (PrimaryVirtualBaseInfo->Derived) {
904  // We did have info about this primary base, and it turns out that it
905  // has already been claimed as a primary virtual base for another
906  // base.
907  PrimaryVirtualBase = nullptr;
908  } else {
909  // We can claim this base as our primary base.
910  Info->PrimaryVirtualBaseInfo = PrimaryVirtualBaseInfo;
911  PrimaryVirtualBaseInfo->Derived = Info;
912  }
913  }
914  }
915  }
916 
917  // Now go through all direct bases.
918  for (const auto &I : RD->bases()) {
919  bool IsVirtual = I.isVirtual();
920 
921  const CXXRecordDecl *BaseDecl = I.getType()->getAsCXXRecordDecl();
922 
923  Info->Bases.push_back(ComputeBaseSubobjectInfo(BaseDecl, IsVirtual, Info));
924  }
925 
926  if (PrimaryVirtualBase && !PrimaryVirtualBaseInfo) {
927  // Traversing the bases must have created the base info for our primary
928  // virtual base.
929  PrimaryVirtualBaseInfo = VirtualBaseInfo.lookup(PrimaryVirtualBase);
930  assert(PrimaryVirtualBaseInfo &&
931  "Did not create a primary virtual base!");
932 
933  // Claim the primary virtual base as our primary virtual base.
934  Info->PrimaryVirtualBaseInfo = PrimaryVirtualBaseInfo;
935  PrimaryVirtualBaseInfo->Derived = Info;
936  }
937 
938  return Info;
939 }
940 
941 void ItaniumRecordLayoutBuilder::ComputeBaseSubobjectInfo(
942  const CXXRecordDecl *RD) {
943  for (const auto &I : RD->bases()) {
944  bool IsVirtual = I.isVirtual();
945 
946  const CXXRecordDecl *BaseDecl = I.getType()->getAsCXXRecordDecl();
947 
948  // Compute the base subobject info for this base.
949  BaseSubobjectInfo *Info = ComputeBaseSubobjectInfo(BaseDecl, IsVirtual,
950  nullptr);
951 
952  if (IsVirtual) {
953  // ComputeBaseInfo has already added this base for us.
954  assert(VirtualBaseInfo.count(BaseDecl) &&
955  "Did not add virtual base!");
956  } else {
957  // Add the base info to the map of non-virtual bases.
958  assert(!NonVirtualBaseInfo.count(BaseDecl) &&
959  "Non-virtual base already exists!");
960  NonVirtualBaseInfo.insert(std::make_pair(BaseDecl, Info));
961  }
962  }
963 }
964 
965 void ItaniumRecordLayoutBuilder::EnsureVTablePointerAlignment(
966  CharUnits UnpackedBaseAlign) {
967  CharUnits BaseAlign = (Packed) ? CharUnits::One() : UnpackedBaseAlign;
968 
969  // The maximum field alignment overrides base align.
970  if (!MaxFieldAlignment.isZero()) {
971  BaseAlign = std::min(BaseAlign, MaxFieldAlignment);
972  UnpackedBaseAlign = std::min(UnpackedBaseAlign, MaxFieldAlignment);
973  }
974 
975  // Round up the current record size to pointer alignment.
976  setSize(getSize().RoundUpToAlignment(BaseAlign));
977  setDataSize(getSize());
978 
979  // Update the alignment.
980  UpdateAlignment(BaseAlign, UnpackedBaseAlign);
981 }
982 
983 void ItaniumRecordLayoutBuilder::LayoutNonVirtualBases(
984  const CXXRecordDecl *RD) {
985  // Then, determine the primary base class.
986  DeterminePrimaryBase(RD);
987 
988  // Compute base subobject info.
989  ComputeBaseSubobjectInfo(RD);
990 
991  // If we have a primary base class, lay it out.
992  if (PrimaryBase) {
993  if (PrimaryBaseIsVirtual) {
994  // If the primary virtual base was a primary virtual base of some other
995  // base class we'll have to steal it.
996  BaseSubobjectInfo *PrimaryBaseInfo = VirtualBaseInfo.lookup(PrimaryBase);
997  PrimaryBaseInfo->Derived = nullptr;
998 
999  // We have a virtual primary base, insert it as an indirect primary base.
1000  IndirectPrimaryBases.insert(PrimaryBase);
1001 
1002  assert(!VisitedVirtualBases.count(PrimaryBase) &&
1003  "vbase already visited!");
1004  VisitedVirtualBases.insert(PrimaryBase);
1005 
1006  LayoutVirtualBase(PrimaryBaseInfo);
1007  } else {
1008  BaseSubobjectInfo *PrimaryBaseInfo =
1009  NonVirtualBaseInfo.lookup(PrimaryBase);
1010  assert(PrimaryBaseInfo &&
1011  "Did not find base info for non-virtual primary base!");
1012 
1013  LayoutNonVirtualBase(PrimaryBaseInfo);
1014  }
1015 
1016  // If this class needs a vtable/vf-table and didn't get one from a
1017  // primary base, add it in now.
1018  } else if (RD->isDynamicClass()) {
1019  assert(DataSize == 0 && "Vtable pointer must be at offset zero!");
1020  CharUnits PtrWidth =
1022  CharUnits PtrAlign =
1024  EnsureVTablePointerAlignment(PtrAlign);
1025  HasOwnVFPtr = true;
1026  setSize(getSize() + PtrWidth);
1027  setDataSize(getSize());
1028  }
1029 
1030  // Now lay out the non-virtual bases.
1031  for (const auto &I : RD->bases()) {
1032 
1033  // Ignore virtual bases.
1034  if (I.isVirtual())
1035  continue;
1036 
1037  const CXXRecordDecl *BaseDecl = I.getType()->getAsCXXRecordDecl();
1038 
1039  // Skip the primary base, because we've already laid it out. The
1040  // !PrimaryBaseIsVirtual check is required because we might have a
1041  // non-virtual base of the same type as a primary virtual base.
1042  if (BaseDecl == PrimaryBase && !PrimaryBaseIsVirtual)
1043  continue;
1044 
1045  // Lay out the base.
1046  BaseSubobjectInfo *BaseInfo = NonVirtualBaseInfo.lookup(BaseDecl);
1047  assert(BaseInfo && "Did not find base info for non-virtual base!");
1048 
1049  LayoutNonVirtualBase(BaseInfo);
1050  }
1051 }
1052 
1053 void ItaniumRecordLayoutBuilder::LayoutNonVirtualBase(
1054  const BaseSubobjectInfo *Base) {
1055  // Layout the base.
1056  CharUnits Offset = LayoutBase(Base);
1057 
1058  // Add its base class offset.
1059  assert(!Bases.count(Base->Class) && "base offset already exists!");
1060  Bases.insert(std::make_pair(Base->Class, Offset));
1061 
1062  AddPrimaryVirtualBaseOffsets(Base, Offset);
1063 }
1064 
1065 void ItaniumRecordLayoutBuilder::AddPrimaryVirtualBaseOffsets(
1066  const BaseSubobjectInfo *Info, CharUnits Offset) {
1067  // This base isn't interesting, it has no virtual bases.
1068  if (!Info->Class->getNumVBases())
1069  return;
1070 
1071  // First, check if we have a virtual primary base to add offsets for.
1072  if (Info->PrimaryVirtualBaseInfo) {
1073  assert(Info->PrimaryVirtualBaseInfo->IsVirtual &&
1074  "Primary virtual base is not virtual!");
1075  if (Info->PrimaryVirtualBaseInfo->Derived == Info) {
1076  // Add the offset.
1077  assert(!VBases.count(Info->PrimaryVirtualBaseInfo->Class) &&
1078  "primary vbase offset already exists!");
1079  VBases.insert(std::make_pair(Info->PrimaryVirtualBaseInfo->Class,
1080  ASTRecordLayout::VBaseInfo(Offset, false)));
1081 
1082  // Traverse the primary virtual base.
1083  AddPrimaryVirtualBaseOffsets(Info->PrimaryVirtualBaseInfo, Offset);
1084  }
1085  }
1086 
1087  // Now go through all direct non-virtual bases.
1088  const ASTRecordLayout &Layout = Context.getASTRecordLayout(Info->Class);
1089  for (const BaseSubobjectInfo *Base : Info->Bases) {
1090  if (Base->IsVirtual)
1091  continue;
1092 
1093  CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base->Class);
1094  AddPrimaryVirtualBaseOffsets(Base, BaseOffset);
1095  }
1096 }
1097 
1098 void ItaniumRecordLayoutBuilder::LayoutVirtualBases(
1099  const CXXRecordDecl *RD, const CXXRecordDecl *MostDerivedClass) {
1100  const CXXRecordDecl *PrimaryBase;
1101  bool PrimaryBaseIsVirtual;
1102 
1103  if (MostDerivedClass == RD) {
1104  PrimaryBase = this->PrimaryBase;
1105  PrimaryBaseIsVirtual = this->PrimaryBaseIsVirtual;
1106  } else {
1107  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1108  PrimaryBase = Layout.getPrimaryBase();
1109  PrimaryBaseIsVirtual = Layout.isPrimaryBaseVirtual();
1110  }
1111 
1112  for (const CXXBaseSpecifier &Base : RD->bases()) {
1113  assert(!Base.getType()->isDependentType() &&
1114  "Cannot layout class with dependent bases.");
1115 
1116  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
1117 
1118  if (Base.isVirtual()) {
1119  if (PrimaryBase != BaseDecl || !PrimaryBaseIsVirtual) {
1120  bool IndirectPrimaryBase = IndirectPrimaryBases.count(BaseDecl);
1121 
1122  // Only lay out the virtual base if it's not an indirect primary base.
1123  if (!IndirectPrimaryBase) {
1124  // Only visit virtual bases once.
1125  if (!VisitedVirtualBases.insert(BaseDecl).second)
1126  continue;
1127 
1128  const BaseSubobjectInfo *BaseInfo = VirtualBaseInfo.lookup(BaseDecl);
1129  assert(BaseInfo && "Did not find virtual base info!");
1130  LayoutVirtualBase(BaseInfo);
1131  }
1132  }
1133  }
1134 
1135  if (!BaseDecl->getNumVBases()) {
1136  // This base isn't interesting since it doesn't have any virtual bases.
1137  continue;
1138  }
1139 
1140  LayoutVirtualBases(BaseDecl, MostDerivedClass);
1141  }
1142 }
1143 
1144 void ItaniumRecordLayoutBuilder::LayoutVirtualBase(
1145  const BaseSubobjectInfo *Base) {
1146  assert(!Base->Derived && "Trying to lay out a primary virtual base!");
1147 
1148  // Layout the base.
1149  CharUnits Offset = LayoutBase(Base);
1150 
1151  // Add its base class offset.
1152  assert(!VBases.count(Base->Class) && "vbase offset already exists!");
1153  VBases.insert(std::make_pair(Base->Class,
1154  ASTRecordLayout::VBaseInfo(Offset, false)));
1155 
1156  AddPrimaryVirtualBaseOffsets(Base, Offset);
1157 }
1158 
1159 CharUnits
1160 ItaniumRecordLayoutBuilder::LayoutBase(const BaseSubobjectInfo *Base) {
1161  const ASTRecordLayout &Layout = Context.getASTRecordLayout(Base->Class);
1162 
1163 
1164  CharUnits Offset;
1165 
1166  // Query the external layout to see if it provides an offset.
1167  bool HasExternalLayout = false;
1168  if (UseExternalLayout) {
1170  if (Base->IsVirtual)
1171  HasExternalLayout = External.getExternalNVBaseOffset(Base->Class, Offset);
1172  else
1173  HasExternalLayout = External.getExternalVBaseOffset(Base->Class, Offset);
1174  }
1175 
1176  CharUnits UnpackedBaseAlign = Layout.getNonVirtualAlignment();
1177  CharUnits BaseAlign = (Packed) ? CharUnits::One() : UnpackedBaseAlign;
1178 
1179  // If we have an empty base class, try to place it at offset 0.
1180  if (Base->Class->isEmpty() &&
1181  (!HasExternalLayout || Offset == CharUnits::Zero()) &&
1182  EmptySubobjects->CanPlaceBaseAtOffset(Base, CharUnits::Zero())) {
1183  setSize(std::max(getSize(), Layout.getSize()));
1184  UpdateAlignment(BaseAlign, UnpackedBaseAlign);
1185 
1186  return CharUnits::Zero();
1187  }
1188 
1189  // The maximum field alignment overrides base align.
1190  if (!MaxFieldAlignment.isZero()) {
1191  BaseAlign = std::min(BaseAlign, MaxFieldAlignment);
1192  UnpackedBaseAlign = std::min(UnpackedBaseAlign, MaxFieldAlignment);
1193  }
1194 
1195  if (!HasExternalLayout) {
1196  // Round up the current record size to the base's alignment boundary.
1197  Offset = getDataSize().RoundUpToAlignment(BaseAlign);
1198 
1199  // Try to place the base.
1200  while (!EmptySubobjects->CanPlaceBaseAtOffset(Base, Offset))
1201  Offset += BaseAlign;
1202  } else {
1203  bool Allowed = EmptySubobjects->CanPlaceBaseAtOffset(Base, Offset);
1204  (void)Allowed;
1205  assert(Allowed && "Base subobject externally placed at overlapping offset");
1206 
1207  if (InferAlignment && Offset < getDataSize().RoundUpToAlignment(BaseAlign)){
1208  // The externally-supplied base offset is before the base offset we
1209  // computed. Assume that the structure is packed.
1210  Alignment = CharUnits::One();
1211  InferAlignment = false;
1212  }
1213  }
1214 
1215  if (!Base->Class->isEmpty()) {
1216  // Update the data size.
1217  setDataSize(Offset + Layout.getNonVirtualSize());
1218 
1219  setSize(std::max(getSize(), getDataSize()));
1220  } else
1221  setSize(std::max(getSize(), Offset + Layout.getSize()));
1222 
1223  // Remember max struct/class alignment.
1224  UpdateAlignment(BaseAlign, UnpackedBaseAlign);
1225 
1226  return Offset;
1227 }
1228 
1229 void ItaniumRecordLayoutBuilder::InitializeLayout(const Decl *D) {
1230  if (const RecordDecl *RD = dyn_cast<RecordDecl>(D)) {
1231  IsUnion = RD->isUnion();
1232  IsMsStruct = RD->isMsStruct(Context);
1233  }
1234 
1235  Packed = D->hasAttr<PackedAttr>();
1236 
1237  // Honor the default struct packing maximum alignment flag.
1238  if (unsigned DefaultMaxFieldAlignment = Context.getLangOpts().PackStruct) {
1239  MaxFieldAlignment = CharUnits::fromQuantity(DefaultMaxFieldAlignment);
1240  }
1241 
1242  // mac68k alignment supersedes maximum field alignment and attribute aligned,
1243  // and forces all structures to have 2-byte alignment. The IBM docs on it
1244  // allude to additional (more complicated) semantics, especially with regard
1245  // to bit-fields, but gcc appears not to follow that.
1246  if (D->hasAttr<AlignMac68kAttr>()) {
1247  IsMac68kAlign = true;
1248  MaxFieldAlignment = CharUnits::fromQuantity(2);
1249  Alignment = CharUnits::fromQuantity(2);
1250  } else {
1251  if (const MaxFieldAlignmentAttr *MFAA = D->getAttr<MaxFieldAlignmentAttr>())
1252  MaxFieldAlignment = Context.toCharUnitsFromBits(MFAA->getAlignment());
1253 
1254  if (unsigned MaxAlign = D->getMaxAlignment())
1255  UpdateAlignment(Context.toCharUnitsFromBits(MaxAlign));
1256  }
1257 
1258  // If there is an external AST source, ask it for the various offsets.
1259  if (const RecordDecl *RD = dyn_cast<RecordDecl>(D))
1260  if (ExternalASTSource *Source = Context.getExternalSource()) {
1261  UseExternalLayout = Source->layoutRecordType(
1262  RD, External.Size, External.Align, External.FieldOffsets,
1263  External.BaseOffsets, External.VirtualBaseOffsets);
1264 
1265  // Update based on external alignment.
1266  if (UseExternalLayout) {
1267  if (External.Align > 0) {
1268  Alignment = Context.toCharUnitsFromBits(External.Align);
1269  } else {
1270  // The external source didn't have alignment information; infer it.
1271  InferAlignment = true;
1272  }
1273  }
1274  }
1275 }
1276 
1277 void ItaniumRecordLayoutBuilder::Layout(const RecordDecl *D) {
1278  InitializeLayout(D);
1279  LayoutFields(D);
1280 
1281  // Finally, round the size of the total struct up to the alignment of the
1282  // struct itself.
1283  FinishLayout(D);
1284 }
1285 
1286 void ItaniumRecordLayoutBuilder::Layout(const CXXRecordDecl *RD) {
1287  InitializeLayout(RD);
1288 
1289  // Lay out the vtable and the non-virtual bases.
1290  LayoutNonVirtualBases(RD);
1291 
1292  LayoutFields(RD);
1293 
1294  NonVirtualSize = Context.toCharUnitsFromBits(
1295  llvm::RoundUpToAlignment(getSizeInBits(),
1297  NonVirtualAlignment = Alignment;
1298 
1299  // Lay out the virtual bases and add the primary virtual base offsets.
1300  LayoutVirtualBases(RD, RD);
1301 
1302  // Finally, round the size of the total struct up to the alignment
1303  // of the struct itself.
1304  FinishLayout(RD);
1305 
1306 #ifndef NDEBUG
1307  // Check that we have base offsets for all bases.
1308  for (const CXXBaseSpecifier &Base : RD->bases()) {
1309  if (Base.isVirtual())
1310  continue;
1311 
1312  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
1313 
1314  assert(Bases.count(BaseDecl) && "Did not find base offset!");
1315  }
1316 
1317  // And all virtual bases.
1318  for (const CXXBaseSpecifier &Base : RD->vbases()) {
1319  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
1320 
1321  assert(VBases.count(BaseDecl) && "Did not find base offset!");
1322  }
1323 #endif
1324 }
1325 
1326 void ItaniumRecordLayoutBuilder::Layout(const ObjCInterfaceDecl *D) {
1327  if (ObjCInterfaceDecl *SD = D->getSuperClass()) {
1329 
1330  UpdateAlignment(SL.getAlignment());
1331 
1332  // We start laying out ivars not at the end of the superclass
1333  // structure, but at the next byte following the last field.
1334  setSize(SL.getDataSize());
1335  setDataSize(getSize());
1336  }
1337 
1338  InitializeLayout(D);
1339  // Layout each ivar sequentially.
1340  for (const ObjCIvarDecl *IVD = D->all_declared_ivar_begin(); IVD;
1341  IVD = IVD->getNextIvar())
1342  LayoutField(IVD, false);
1343 
1344  // Finally, round the size of the total struct up to the alignment of the
1345  // struct itself.
1346  FinishLayout(D);
1347 }
1348 
1349 void ItaniumRecordLayoutBuilder::LayoutFields(const RecordDecl *D) {
1350  // Layout each field, for now, just sequentially, respecting alignment. In
1351  // the future, this will need to be tweakable by targets.
1352  bool InsertExtraPadding = D->mayInsertExtraPadding(/*EmitRemark=*/true);
1353  bool HasFlexibleArrayMember = D->hasFlexibleArrayMember();
1354  for (auto I = D->field_begin(), End = D->field_end(); I != End; ++I) {
1355  auto Next(I);
1356  ++Next;
1357  LayoutField(*I,
1358  InsertExtraPadding && (Next != End || !HasFlexibleArrayMember));
1359  }
1360 }
1361 
1362 // Rounds the specified size to have it a multiple of the char size.
1363 static uint64_t
1365  const ASTContext &Context) {
1366  uint64_t CharAlignment = Context.getTargetInfo().getCharAlign();
1367  return llvm::RoundUpToAlignment(Size, CharAlignment);
1368 }
1369 
1370 void ItaniumRecordLayoutBuilder::LayoutWideBitField(uint64_t FieldSize,
1371  uint64_t TypeSize,
1372  bool FieldPacked,
1373  const FieldDecl *D) {
1374  assert(Context.getLangOpts().CPlusPlus &&
1375  "Can only have wide bit-fields in C++!");
1376 
1377  // Itanium C++ ABI 2.4:
1378  // If sizeof(T)*8 < n, let T' be the largest integral POD type with
1379  // sizeof(T')*8 <= n.
1380 
1381  QualType IntegralPODTypes[] = {
1384  };
1385 
1386  QualType Type;
1387  for (const QualType &QT : IntegralPODTypes) {
1388  uint64_t Size = Context.getTypeSize(QT);
1389 
1390  if (Size > FieldSize)
1391  break;
1392 
1393  Type = QT;
1394  }
1395  assert(!Type.isNull() && "Did not find a type!");
1396 
1397  CharUnits TypeAlign = Context.getTypeAlignInChars(Type);
1398 
1399  // We're not going to use any of the unfilled bits in the last byte.
1400  UnfilledBitsInLastUnit = 0;
1401  LastBitfieldTypeSize = 0;
1402 
1403  uint64_t FieldOffset;
1404  uint64_t UnpaddedFieldOffset = getDataSizeInBits() - UnfilledBitsInLastUnit;
1405 
1406  if (IsUnion) {
1407  uint64_t RoundedFieldSize = roundUpSizeToCharAlignment(FieldSize,
1408  Context);
1409  setDataSize(std::max(getDataSizeInBits(), RoundedFieldSize));
1410  FieldOffset = 0;
1411  } else {
1412  // The bitfield is allocated starting at the next offset aligned
1413  // appropriately for T', with length n bits.
1414  FieldOffset = llvm::RoundUpToAlignment(getDataSizeInBits(),
1415  Context.toBits(TypeAlign));
1416 
1417  uint64_t NewSizeInBits = FieldOffset + FieldSize;
1418 
1419  setDataSize(llvm::RoundUpToAlignment(NewSizeInBits,
1421  UnfilledBitsInLastUnit = getDataSizeInBits() - NewSizeInBits;
1422  }
1423 
1424  // Place this field at the current location.
1425  FieldOffsets.push_back(FieldOffset);
1426 
1427  CheckFieldPadding(FieldOffset, UnpaddedFieldOffset, FieldOffset,
1428  Context.toBits(TypeAlign), FieldPacked, D);
1429 
1430  // Update the size.
1431  setSize(std::max(getSizeInBits(), getDataSizeInBits()));
1432 
1433  // Remember max struct/class alignment.
1434  UpdateAlignment(TypeAlign);
1435 }
1436 
1437 void ItaniumRecordLayoutBuilder::LayoutBitField(const FieldDecl *D) {
1438  bool FieldPacked = Packed || D->hasAttr<PackedAttr>();
1439  uint64_t FieldSize = D->getBitWidthValue(Context);
1440  TypeInfo FieldInfo = Context.getTypeInfo(D->getType());
1441  uint64_t TypeSize = FieldInfo.Width;
1442  unsigned FieldAlign = FieldInfo.Align;
1443 
1444  // UnfilledBitsInLastUnit is the difference between the end of the
1445  // last allocated bitfield (i.e. the first bit offset available for
1446  // bitfields) and the end of the current data size in bits (i.e. the
1447  // first bit offset available for non-bitfields). The current data
1448  // size in bits is always a multiple of the char size; additionally,
1449  // for ms_struct records it's also a multiple of the
1450  // LastBitfieldTypeSize (if set).
1451 
1452  // The struct-layout algorithm is dictated by the platform ABI,
1453  // which in principle could use almost any rules it likes. In
1454  // practice, UNIXy targets tend to inherit the algorithm described
1455  // in the System V generic ABI. The basic bitfield layout rule in
1456  // System V is to place bitfields at the next available bit offset
1457  // where the entire bitfield would fit in an aligned storage unit of
1458  // the declared type; it's okay if an earlier or later non-bitfield
1459  // is allocated in the same storage unit. However, some targets
1460  // (those that !useBitFieldTypeAlignment(), e.g. ARM APCS) don't
1461  // require this storage unit to be aligned, and therefore always put
1462  // the bitfield at the next available bit offset.
1463 
1464  // ms_struct basically requests a complete replacement of the
1465  // platform ABI's struct-layout algorithm, with the high-level goal
1466  // of duplicating MSVC's layout. For non-bitfields, this follows
1467  // the standard algorithm. The basic bitfield layout rule is to
1468  // allocate an entire unit of the bitfield's declared type
1469  // (e.g. 'unsigned long'), then parcel it up among successive
1470  // bitfields whose declared types have the same size, making a new
1471  // unit as soon as the last can no longer store the whole value.
1472  // Since it completely replaces the platform ABI's algorithm,
1473  // settings like !useBitFieldTypeAlignment() do not apply.
1474 
1475  // A zero-width bitfield forces the use of a new storage unit for
1476  // later bitfields. In general, this occurs by rounding up the
1477  // current size of the struct as if the algorithm were about to
1478  // place a non-bitfield of the field's formal type. Usually this
1479  // does not change the alignment of the struct itself, but it does
1480  // on some targets (those that useZeroLengthBitfieldAlignment(),
1481  // e.g. ARM). In ms_struct layout, zero-width bitfields are
1482  // ignored unless they follow a non-zero-width bitfield.
1483 
1484  // A field alignment restriction (e.g. from #pragma pack) or
1485  // specification (e.g. from __attribute__((aligned))) changes the
1486  // formal alignment of the field. For System V, this alters the
1487  // required alignment of the notional storage unit that must contain
1488  // the bitfield. For ms_struct, this only affects the placement of
1489  // new storage units. In both cases, the effect of #pragma pack is
1490  // ignored on zero-width bitfields.
1491 
1492  // On System V, a packed field (e.g. from #pragma pack or
1493  // __attribute__((packed))) always uses the next available bit
1494  // offset.
1495 
1496  // In an ms_struct struct, the alignment of a fundamental type is
1497  // always equal to its size. This is necessary in order to mimic
1498  // the i386 alignment rules on targets which might not fully align
1499  // all types (e.g. Darwin PPC32, where alignof(long long) == 4).
1500 
1501  // First, some simple bookkeeping to perform for ms_struct structs.
1502  if (IsMsStruct) {
1503  // The field alignment for integer types is always the size.
1504  FieldAlign = TypeSize;
1505 
1506  // If the previous field was not a bitfield, or was a bitfield
1507  // with a different storage unit size, we're done with that
1508  // storage unit.
1509  if (LastBitfieldTypeSize != TypeSize) {
1510  // Also, ignore zero-length bitfields after non-bitfields.
1511  if (!LastBitfieldTypeSize && !FieldSize)
1512  FieldAlign = 1;
1513 
1514  UnfilledBitsInLastUnit = 0;
1515  LastBitfieldTypeSize = 0;
1516  }
1517  }
1518 
1519  // If the field is wider than its declared type, it follows
1520  // different rules in all cases.
1521  if (FieldSize > TypeSize) {
1522  LayoutWideBitField(FieldSize, TypeSize, FieldPacked, D);
1523  return;
1524  }
1525 
1526  // Compute the next available bit offset.
1527  uint64_t FieldOffset =
1528  IsUnion ? 0 : (getDataSizeInBits() - UnfilledBitsInLastUnit);
1529 
1530  // Handle targets that don't honor bitfield type alignment.
1531  if (!IsMsStruct && !Context.getTargetInfo().useBitFieldTypeAlignment()) {
1532  // Some such targets do honor it on zero-width bitfields.
1533  if (FieldSize == 0 &&
1535  // The alignment to round up to is the max of the field's natural
1536  // alignment and a target-specific fixed value (sometimes zero).
1537  unsigned ZeroLengthBitfieldBoundary =
1539  FieldAlign = std::max(FieldAlign, ZeroLengthBitfieldBoundary);
1540 
1541  // If that doesn't apply, just ignore the field alignment.
1542  } else {
1543  FieldAlign = 1;
1544  }
1545  }
1546 
1547  // Remember the alignment we would have used if the field were not packed.
1548  unsigned UnpackedFieldAlign = FieldAlign;
1549 
1550  // Ignore the field alignment if the field is packed unless it has zero-size.
1551  if (!IsMsStruct && FieldPacked && FieldSize != 0)
1552  FieldAlign = 1;
1553 
1554  // But, if there's an 'aligned' attribute on the field, honor that.
1555  unsigned ExplicitFieldAlign = D->getMaxAlignment();
1556  if (ExplicitFieldAlign) {
1557  FieldAlign = std::max(FieldAlign, ExplicitFieldAlign);
1558  UnpackedFieldAlign = std::max(UnpackedFieldAlign, ExplicitFieldAlign);
1559  }
1560 
1561  // But, if there's a #pragma pack in play, that takes precedent over
1562  // even the 'aligned' attribute, for non-zero-width bitfields.
1563  if (!MaxFieldAlignment.isZero() && FieldSize) {
1564  unsigned MaxFieldAlignmentInBits = Context.toBits(MaxFieldAlignment);
1565  FieldAlign = std::min(FieldAlign, MaxFieldAlignmentInBits);
1566  UnpackedFieldAlign = std::min(UnpackedFieldAlign, MaxFieldAlignmentInBits);
1567  }
1568 
1569  // But, ms_struct just ignores all of that in unions, even explicit
1570  // alignment attributes.
1571  if (IsMsStruct && IsUnion) {
1572  FieldAlign = UnpackedFieldAlign = 1;
1573  }
1574 
1575  // For purposes of diagnostics, we're going to simultaneously
1576  // compute the field offsets that we would have used if we weren't
1577  // adding any alignment padding or if the field weren't packed.
1578  uint64_t UnpaddedFieldOffset = FieldOffset;
1579  uint64_t UnpackedFieldOffset = FieldOffset;
1580 
1581  // Check if we need to add padding to fit the bitfield within an
1582  // allocation unit with the right size and alignment. The rules are
1583  // somewhat different here for ms_struct structs.
1584  if (IsMsStruct) {
1585  // If it's not a zero-width bitfield, and we can fit the bitfield
1586  // into the active storage unit (and we haven't already decided to
1587  // start a new storage unit), just do so, regardless of any other
1588  // other consideration. Otherwise, round up to the right alignment.
1589  if (FieldSize == 0 || FieldSize > UnfilledBitsInLastUnit) {
1590  FieldOffset = llvm::RoundUpToAlignment(FieldOffset, FieldAlign);
1591  UnpackedFieldOffset = llvm::RoundUpToAlignment(UnpackedFieldOffset,
1592  UnpackedFieldAlign);
1593  UnfilledBitsInLastUnit = 0;
1594  }
1595 
1596  } else {
1597  // #pragma pack, with any value, suppresses the insertion of padding.
1598  bool AllowPadding = MaxFieldAlignment.isZero();
1599 
1600  // Compute the real offset.
1601  if (FieldSize == 0 ||
1602  (AllowPadding &&
1603  (FieldOffset & (FieldAlign-1)) + FieldSize > TypeSize)) {
1604  FieldOffset = llvm::RoundUpToAlignment(FieldOffset, FieldAlign);
1605  } else if (ExplicitFieldAlign) {
1606  // TODO: figure it out what needs to be done on targets that don't honor
1607  // bit-field type alignment like ARM APCS ABI.
1608  FieldOffset = llvm::RoundUpToAlignment(FieldOffset, ExplicitFieldAlign);
1609  }
1610 
1611  // Repeat the computation for diagnostic purposes.
1612  if (FieldSize == 0 ||
1613  (AllowPadding &&
1614  (UnpackedFieldOffset & (UnpackedFieldAlign-1)) + FieldSize > TypeSize))
1615  UnpackedFieldOffset = llvm::RoundUpToAlignment(UnpackedFieldOffset,
1616  UnpackedFieldAlign);
1617  else if (ExplicitFieldAlign)
1618  UnpackedFieldOffset = llvm::RoundUpToAlignment(UnpackedFieldOffset,
1619  ExplicitFieldAlign);
1620  }
1621 
1622  // If we're using external layout, give the external layout a chance
1623  // to override this information.
1624  if (UseExternalLayout)
1625  FieldOffset = updateExternalFieldOffset(D, FieldOffset);
1626 
1627  // Okay, place the bitfield at the calculated offset.
1628  FieldOffsets.push_back(FieldOffset);
1629 
1630  // Bookkeeping:
1631 
1632  // Anonymous members don't affect the overall record alignment,
1633  // except on targets where they do.
1634  if (!IsMsStruct &&
1636  !D->getIdentifier())
1637  FieldAlign = UnpackedFieldAlign = 1;
1638 
1639  // Diagnose differences in layout due to padding or packing.
1640  if (!UseExternalLayout)
1641  CheckFieldPadding(FieldOffset, UnpaddedFieldOffset, UnpackedFieldOffset,
1642  UnpackedFieldAlign, FieldPacked, D);
1643 
1644  // Update DataSize to include the last byte containing (part of) the bitfield.
1645 
1646  // For unions, this is just a max operation, as usual.
1647  if (IsUnion) {
1648  // For ms_struct, allocate the entire storage unit --- unless this
1649  // is a zero-width bitfield, in which case just use a size of 1.
1650  uint64_t RoundedFieldSize;
1651  if (IsMsStruct) {
1652  RoundedFieldSize =
1653  (FieldSize ? TypeSize : Context.getTargetInfo().getCharWidth());
1654 
1655  // Otherwise, allocate just the number of bytes required to store
1656  // the bitfield.
1657  } else {
1658  RoundedFieldSize = roundUpSizeToCharAlignment(FieldSize, Context);
1659  }
1660  setDataSize(std::max(getDataSizeInBits(), RoundedFieldSize));
1661 
1662  // For non-zero-width bitfields in ms_struct structs, allocate a new
1663  // storage unit if necessary.
1664  } else if (IsMsStruct && FieldSize) {
1665  // We should have cleared UnfilledBitsInLastUnit in every case
1666  // where we changed storage units.
1667  if (!UnfilledBitsInLastUnit) {
1668  setDataSize(FieldOffset + TypeSize);
1669  UnfilledBitsInLastUnit = TypeSize;
1670  }
1671  UnfilledBitsInLastUnit -= FieldSize;
1672  LastBitfieldTypeSize = TypeSize;
1673 
1674  // Otherwise, bump the data size up to include the bitfield,
1675  // including padding up to char alignment, and then remember how
1676  // bits we didn't use.
1677  } else {
1678  uint64_t NewSizeInBits = FieldOffset + FieldSize;
1679  uint64_t CharAlignment = Context.getTargetInfo().getCharAlign();
1680  setDataSize(llvm::RoundUpToAlignment(NewSizeInBits, CharAlignment));
1681  UnfilledBitsInLastUnit = getDataSizeInBits() - NewSizeInBits;
1682 
1683  // The only time we can get here for an ms_struct is if this is a
1684  // zero-width bitfield, which doesn't count as anything for the
1685  // purposes of unfilled bits.
1686  LastBitfieldTypeSize = 0;
1687  }
1688 
1689  // Update the size.
1690  setSize(std::max(getSizeInBits(), getDataSizeInBits()));
1691 
1692  // Remember max struct/class alignment.
1693  UpdateAlignment(Context.toCharUnitsFromBits(FieldAlign),
1694  Context.toCharUnitsFromBits(UnpackedFieldAlign));
1695 }
1696 
1697 void ItaniumRecordLayoutBuilder::LayoutField(const FieldDecl *D,
1698  bool InsertExtraPadding) {
1699  if (D->isBitField()) {
1700  LayoutBitField(D);
1701  return;
1702  }
1703 
1704  uint64_t UnpaddedFieldOffset = getDataSizeInBits() - UnfilledBitsInLastUnit;
1705 
1706  // Reset the unfilled bits.
1707  UnfilledBitsInLastUnit = 0;
1708  LastBitfieldTypeSize = 0;
1709 
1710  bool FieldPacked = Packed || D->hasAttr<PackedAttr>();
1711  CharUnits FieldOffset =
1712  IsUnion ? CharUnits::Zero() : getDataSize();
1713  CharUnits FieldSize;
1714  CharUnits FieldAlign;
1715 
1716  if (D->getType()->isIncompleteArrayType()) {
1717  // This is a flexible array member; we can't directly
1718  // query getTypeInfo about these, so we figure it out here.
1719  // Flexible array members don't have any size, but they
1720  // have to be aligned appropriately for their element type.
1721  FieldSize = CharUnits::Zero();
1722  const ArrayType* ATy = Context.getAsArrayType(D->getType());
1723  FieldAlign = Context.getTypeAlignInChars(ATy->getElementType());
1724  } else if (const ReferenceType *RT = D->getType()->getAs<ReferenceType>()) {
1725  unsigned AS = RT->getPointeeType().getAddressSpace();
1726  FieldSize =
1728  FieldAlign =
1730  } else {
1731  std::pair<CharUnits, CharUnits> FieldInfo =
1733  FieldSize = FieldInfo.first;
1734  FieldAlign = FieldInfo.second;
1735 
1736  if (IsMsStruct) {
1737  // If MS bitfield layout is required, figure out what type is being
1738  // laid out and align the field to the width of that type.
1739 
1740  // Resolve all typedefs down to their base type and round up the field
1741  // alignment if necessary.
1743  if (const BuiltinType *BTy = T->getAs<BuiltinType>()) {
1744  CharUnits TypeSize = Context.getTypeSizeInChars(BTy);
1745  if (TypeSize > FieldAlign)
1746  FieldAlign = TypeSize;
1747  }
1748  }
1749  }
1750 
1751  // The align if the field is not packed. This is to check if the attribute
1752  // was unnecessary (-Wpacked).
1753  CharUnits UnpackedFieldAlign = FieldAlign;
1754  CharUnits UnpackedFieldOffset = FieldOffset;
1755 
1756  if (FieldPacked)
1757  FieldAlign = CharUnits::One();
1758  CharUnits MaxAlignmentInChars =
1760  FieldAlign = std::max(FieldAlign, MaxAlignmentInChars);
1761  UnpackedFieldAlign = std::max(UnpackedFieldAlign, MaxAlignmentInChars);
1762 
1763  // The maximum field alignment overrides the aligned attribute.
1764  if (!MaxFieldAlignment.isZero()) {
1765  FieldAlign = std::min(FieldAlign, MaxFieldAlignment);
1766  UnpackedFieldAlign = std::min(UnpackedFieldAlign, MaxFieldAlignment);
1767  }
1768 
1769  // Round up the current record size to the field's alignment boundary.
1770  FieldOffset = FieldOffset.RoundUpToAlignment(FieldAlign);
1771  UnpackedFieldOffset =
1772  UnpackedFieldOffset.RoundUpToAlignment(UnpackedFieldAlign);
1773 
1774  if (UseExternalLayout) {
1775  FieldOffset = Context.toCharUnitsFromBits(
1776  updateExternalFieldOffset(D, Context.toBits(FieldOffset)));
1777 
1778  if (!IsUnion && EmptySubobjects) {
1779  // Record the fact that we're placing a field at this offset.
1780  bool Allowed = EmptySubobjects->CanPlaceFieldAtOffset(D, FieldOffset);
1781  (void)Allowed;
1782  assert(Allowed && "Externally-placed field cannot be placed here");
1783  }
1784  } else {
1785  if (!IsUnion && EmptySubobjects) {
1786  // Check if we can place the field at this offset.
1787  while (!EmptySubobjects->CanPlaceFieldAtOffset(D, FieldOffset)) {
1788  // We couldn't place the field at the offset. Try again at a new offset.
1789  FieldOffset += FieldAlign;
1790  }
1791  }
1792  }
1793 
1794  // Place this field at the current location.
1795  FieldOffsets.push_back(Context.toBits(FieldOffset));
1796 
1797  if (!UseExternalLayout)
1798  CheckFieldPadding(Context.toBits(FieldOffset), UnpaddedFieldOffset,
1799  Context.toBits(UnpackedFieldOffset),
1800  Context.toBits(UnpackedFieldAlign), FieldPacked, D);
1801 
1802  if (InsertExtraPadding) {
1803  CharUnits ASanAlignment = CharUnits::fromQuantity(8);
1804  CharUnits ExtraSizeForAsan = ASanAlignment;
1805  if (FieldSize % ASanAlignment)
1806  ExtraSizeForAsan +=
1807  ASanAlignment - CharUnits::fromQuantity(FieldSize % ASanAlignment);
1808  FieldSize += ExtraSizeForAsan;
1809  }
1810 
1811  // Reserve space for this field.
1812  uint64_t FieldSizeInBits = Context.toBits(FieldSize);
1813  if (IsUnion)
1814  setDataSize(std::max(getDataSizeInBits(), FieldSizeInBits));
1815  else
1816  setDataSize(FieldOffset + FieldSize);
1817 
1818  // Update the size.
1819  setSize(std::max(getSizeInBits(), getDataSizeInBits()));
1820 
1821  // Remember max struct/class alignment.
1822  UpdateAlignment(FieldAlign, UnpackedFieldAlign);
1823 }
1824 
1825 void ItaniumRecordLayoutBuilder::FinishLayout(const NamedDecl *D) {
1826  // In C++, records cannot be of size 0.
1827  if (Context.getLangOpts().CPlusPlus && getSizeInBits() == 0) {
1828  if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D)) {
1829  // Compatibility with gcc requires a class (pod or non-pod)
1830  // which is not empty but of size 0; such as having fields of
1831  // array of zero-length, remains of Size 0
1832  if (RD->isEmpty())
1833  setSize(CharUnits::One());
1834  }
1835  else
1836  setSize(CharUnits::One());
1837  }
1838 
1839  // Finally, round the size of the record up to the alignment of the
1840  // record itself.
1841  uint64_t UnpaddedSize = getSizeInBits() - UnfilledBitsInLastUnit;
1842  uint64_t UnpackedSizeInBits =
1843  llvm::RoundUpToAlignment(getSizeInBits(),
1844  Context.toBits(UnpackedAlignment));
1845  CharUnits UnpackedSize = Context.toCharUnitsFromBits(UnpackedSizeInBits);
1846  uint64_t RoundedSize
1847  = llvm::RoundUpToAlignment(getSizeInBits(), Context.toBits(Alignment));
1848 
1849  if (UseExternalLayout) {
1850  // If we're inferring alignment, and the external size is smaller than
1851  // our size after we've rounded up to alignment, conservatively set the
1852  // alignment to 1.
1853  if (InferAlignment && External.Size < RoundedSize) {
1854  Alignment = CharUnits::One();
1855  InferAlignment = false;
1856  }
1857  setSize(External.Size);
1858  return;
1859  }
1860 
1861  // Set the size to the final size.
1862  setSize(RoundedSize);
1863 
1864  unsigned CharBitNum = Context.getTargetInfo().getCharWidth();
1865  if (const RecordDecl *RD = dyn_cast<RecordDecl>(D)) {
1866  // Warn if padding was introduced to the struct/class/union.
1867  if (getSizeInBits() > UnpaddedSize) {
1868  unsigned PadSize = getSizeInBits() - UnpaddedSize;
1869  bool InBits = true;
1870  if (PadSize % CharBitNum == 0) {
1871  PadSize = PadSize / CharBitNum;
1872  InBits = false;
1873  }
1874  Diag(RD->getLocation(), diag::warn_padded_struct_size)
1875  << Context.getTypeDeclType(RD)
1876  << PadSize
1877  << (InBits ? 1 : 0); // (byte|bit)
1878  }
1879 
1880  // Warn if we packed it unnecessarily. If the alignment is 1 byte don't
1881  // bother since there won't be alignment issues.
1882  if (Packed && UnpackedAlignment > CharUnits::One() &&
1883  getSize() == UnpackedSize)
1884  Diag(D->getLocation(), diag::warn_unnecessary_packed)
1885  << Context.getTypeDeclType(RD);
1886  }
1887 }
1888 
1889 void ItaniumRecordLayoutBuilder::UpdateAlignment(
1890  CharUnits NewAlignment, CharUnits UnpackedNewAlignment) {
1891  // The alignment is not modified when using 'mac68k' alignment or when
1892  // we have an externally-supplied layout that also provides overall alignment.
1893  if (IsMac68kAlign || (UseExternalLayout && !InferAlignment))
1894  return;
1895 
1896  if (NewAlignment > Alignment) {
1897  assert(llvm::isPowerOf2_64(NewAlignment.getQuantity()) &&
1898  "Alignment not a power of 2");
1899  Alignment = NewAlignment;
1900  }
1901 
1902  if (UnpackedNewAlignment > UnpackedAlignment) {
1903  assert(llvm::isPowerOf2_64(UnpackedNewAlignment.getQuantity()) &&
1904  "Alignment not a power of 2");
1905  UnpackedAlignment = UnpackedNewAlignment;
1906  }
1907 }
1908 
1909 uint64_t
1910 ItaniumRecordLayoutBuilder::updateExternalFieldOffset(const FieldDecl *Field,
1911  uint64_t ComputedOffset) {
1912  uint64_t ExternalFieldOffset = External.getExternalFieldOffset(Field);
1913 
1914  if (InferAlignment && ExternalFieldOffset < ComputedOffset) {
1915  // The externally-supplied field offset is before the field offset we
1916  // computed. Assume that the structure is packed.
1917  Alignment = CharUnits::One();
1918  InferAlignment = false;
1919  }
1920 
1921  // Use the externally-supplied field offset.
1922  return ExternalFieldOffset;
1923 }
1924 
1925 /// \brief Get diagnostic %select index for tag kind for
1926 /// field padding diagnostic message.
1927 /// WARNING: Indexes apply to particular diagnostics only!
1928 ///
1929 /// \returns diagnostic %select index.
1931  switch (Tag) {
1932  case TTK_Struct: return 0;
1933  case TTK_Interface: return 1;
1934  case TTK_Class: return 2;
1935  default: llvm_unreachable("Invalid tag kind for field padding diagnostic!");
1936  }
1937 }
1938 
1939 void ItaniumRecordLayoutBuilder::CheckFieldPadding(
1940  uint64_t Offset, uint64_t UnpaddedOffset, uint64_t UnpackedOffset,
1941  unsigned UnpackedAlign, bool isPacked, const FieldDecl *D) {
1942  // We let objc ivars without warning, objc interfaces generally are not used
1943  // for padding tricks.
1944  if (isa<ObjCIvarDecl>(D))
1945  return;
1946 
1947  // Don't warn about structs created without a SourceLocation. This can
1948  // be done by clients of the AST, such as codegen.
1949  if (D->getLocation().isInvalid())
1950  return;
1951 
1952  unsigned CharBitNum = Context.getTargetInfo().getCharWidth();
1953 
1954  // Warn if padding was introduced to the struct/class.
1955  if (!IsUnion && Offset > UnpaddedOffset) {
1956  unsigned PadSize = Offset - UnpaddedOffset;
1957  bool InBits = true;
1958  if (PadSize % CharBitNum == 0) {
1959  PadSize = PadSize / CharBitNum;
1960  InBits = false;
1961  }
1962  if (D->getIdentifier())
1963  Diag(D->getLocation(), diag::warn_padded_struct_field)
1966  << PadSize
1967  << (InBits ? 1 : 0) // (byte|bit)
1968  << D->getIdentifier();
1969  else
1970  Diag(D->getLocation(), diag::warn_padded_struct_anon_field)
1973  << PadSize
1974  << (InBits ? 1 : 0); // (byte|bit)
1975  }
1976 
1977  // Warn if we packed it unnecessarily. If the alignment is 1 byte don't
1978  // bother since there won't be alignment issues.
1979  if (isPacked && UnpackedAlign > CharBitNum && Offset == UnpackedOffset)
1980  Diag(D->getLocation(), diag::warn_unnecessary_packed)
1981  << D->getIdentifier();
1982 }
1983 
1985  const CXXRecordDecl *RD) {
1986  // If a class isn't polymorphic it doesn't have a key function.
1987  if (!RD->isPolymorphic())
1988  return nullptr;
1989 
1990  // A class that is not externally visible doesn't have a key function. (Or
1991  // at least, there's no point to assigning a key function to such a class;
1992  // this doesn't affect the ABI.)
1993  if (!RD->isExternallyVisible())
1994  return nullptr;
1995 
1996  // Template instantiations don't have key functions per Itanium C++ ABI 5.2.6.
1997  // Same behavior as GCC.
1999  if (TSK == TSK_ImplicitInstantiation ||
2002  return nullptr;
2003 
2004  bool allowInlineFunctions =
2006 
2007  for (const CXXMethodDecl *MD : RD->methods()) {
2008  if (!MD->isVirtual())
2009  continue;
2010 
2011  if (MD->isPure())
2012  continue;
2013 
2014  // Ignore implicit member functions, they are always marked as inline, but
2015  // they don't have a body until they're defined.
2016  if (MD->isImplicit())
2017  continue;
2018 
2019  if (MD->isInlineSpecified())
2020  continue;
2021 
2022  if (MD->hasInlineBody())
2023  continue;
2024 
2025  // Ignore inline deleted or defaulted functions.
2026  if (!MD->isUserProvided())
2027  continue;
2028 
2029  // In certain ABIs, ignore functions with out-of-line inline definitions.
2030  if (!allowInlineFunctions) {
2031  const FunctionDecl *Def;
2032  if (MD->hasBody(Def) && Def->isInlineSpecified())
2033  continue;
2034  }
2035 
2036  if (Context.getLangOpts().CUDA) {
2037  // While compiler may see key method in this TU, during CUDA
2038  // compilation we should ignore methods that are not accessible
2039  // on this side of compilation.
2040  if (Context.getLangOpts().CUDAIsDevice) {
2041  // In device mode ignore methods without __device__ attribute.
2042  if (!MD->hasAttr<CUDADeviceAttr>())
2043  continue;
2044  } else {
2045  // In host mode ignore __device__-only methods.
2046  if (!MD->hasAttr<CUDAHostAttr>() && MD->hasAttr<CUDADeviceAttr>())
2047  continue;
2048  }
2049  }
2050 
2051  // If the key function is dllimport but the class isn't, then the class has
2052  // no key function. The DLL that exports the key function won't export the
2053  // vtable in this case.
2054  if (MD->hasAttr<DLLImportAttr>() && !RD->hasAttr<DLLImportAttr>())
2055  return nullptr;
2056 
2057  // We found it.
2058  return MD;
2059  }
2060 
2061  return nullptr;
2062 }
2063 
2065  unsigned DiagID) {
2066  return Context.getDiagnostics().Report(Loc, DiagID);
2067 }
2068 
2069 /// Does the target C++ ABI require us to skip over the tail-padding
2070 /// of the given class (considering it as a base class) when allocating
2071 /// objects?
2072 static bool mustSkipTailPadding(TargetCXXABI ABI, const CXXRecordDecl *RD) {
2073  switch (ABI.getTailPaddingUseRules()) {
2075  return false;
2076 
2078  // FIXME: To the extent that this is meant to cover the Itanium ABI
2079  // rules, we should implement the restrictions about over-sized
2080  // bitfields:
2081  //
2082  // http://mentorembedded.github.com/cxx-abi/abi.html#POD :
2083  // In general, a type is considered a POD for the purposes of
2084  // layout if it is a POD type (in the sense of ISO C++
2085  // [basic.types]). However, a POD-struct or POD-union (in the
2086  // sense of ISO C++ [class]) with a bitfield member whose
2087  // declared width is wider than the declared type of the
2088  // bitfield is not a POD for the purpose of layout. Similarly,
2089  // an array type is not a POD for the purpose of layout if the
2090  // element type of the array is not a POD for the purpose of
2091  // layout.
2092  //
2093  // Where references to the ISO C++ are made in this paragraph,
2094  // the Technical Corrigendum 1 version of the standard is
2095  // intended.
2096  return RD->isPOD();
2097 
2099  // This is equivalent to RD->getTypeForDecl().isCXX11PODType(),
2100  // but with a lot of abstraction penalty stripped off. This does
2101  // assume that these properties are set correctly even in C++98
2102  // mode; fortunately, that is true because we want to assign
2103  // consistently semantics to the type-traits intrinsics (or at
2104  // least as many of them as possible).
2105  return RD->isTrivial() && RD->isStandardLayout();
2106  }
2107 
2108  llvm_unreachable("bad tail-padding use kind");
2109 }
2110 
2111 static bool isMsLayout(const ASTContext &Context) {
2112  return Context.getTargetInfo().getCXXABI().isMicrosoft();
2113 }
2114 
2115 // This section contains an implementation of struct layout that is, up to the
2116 // included tests, compatible with cl.exe (2013). The layout produced is
2117 // significantly different than those produced by the Itanium ABI. Here we note
2118 // the most important differences.
2119 //
2120 // * The alignment of bitfields in unions is ignored when computing the
2121 // alignment of the union.
2122 // * The existence of zero-width bitfield that occurs after anything other than
2123 // a non-zero length bitfield is ignored.
2124 // * There is no explicit primary base for the purposes of layout. All bases
2125 // with vfptrs are laid out first, followed by all bases without vfptrs.
2126 // * The Itanium equivalent vtable pointers are split into a vfptr (virtual
2127 // function pointer) and a vbptr (virtual base pointer). They can each be
2128 // shared with a, non-virtual bases. These bases need not be the same. vfptrs
2129 // always occur at offset 0. vbptrs can occur at an arbitrary offset and are
2130 // placed after the lexiographically last non-virtual base. This placement
2131 // is always before fields but can be in the middle of the non-virtual bases
2132 // due to the two-pass layout scheme for non-virtual-bases.
2133 // * Virtual bases sometimes require a 'vtordisp' field that is laid out before
2134 // the virtual base and is used in conjunction with virtual overrides during
2135 // construction and destruction. This is always a 4 byte value and is used as
2136 // an alternative to constructor vtables.
2137 // * vtordisps are allocated in a block of memory with size and alignment equal
2138 // to the alignment of the completed structure (before applying __declspec(
2139 // align())). The vtordisp always occur at the end of the allocation block,
2140 // immediately prior to the virtual base.
2141 // * vfptrs are injected after all bases and fields have been laid out. In
2142 // order to guarantee proper alignment of all fields, the vfptr injection
2143 // pushes all bases and fields back by the alignment imposed by those bases
2144 // and fields. This can potentially add a significant amount of padding.
2145 // vfptrs are always injected at offset 0.
2146 // * vbptrs are injected after all bases and fields have been laid out. In
2147 // order to guarantee proper alignment of all fields, the vfptr injection
2148 // pushes all bases and fields back by the alignment imposed by those bases
2149 // and fields. This can potentially add a significant amount of padding.
2150 // vbptrs are injected immediately after the last non-virtual base as
2151 // lexiographically ordered in the code. If this site isn't pointer aligned
2152 // the vbptr is placed at the next properly aligned location. Enough padding
2153 // is added to guarantee a fit.
2154 // * The last zero sized non-virtual base can be placed at the end of the
2155 // struct (potentially aliasing another object), or may alias with the first
2156 // field, even if they are of the same type.
2157 // * The last zero size virtual base may be placed at the end of the struct
2158 // potentially aliasing another object.
2159 // * The ABI attempts to avoid aliasing of zero sized bases by adding padding
2160 // between bases or vbases with specific properties. The criteria for
2161 // additional padding between two bases is that the first base is zero sized
2162 // or ends with a zero sized subobject and the second base is zero sized or
2163 // trails with a zero sized base or field (sharing of vfptrs can reorder the
2164 // layout of the so the leading base is not always the first one declared).
2165 // This rule does take into account fields that are not records, so padding
2166 // will occur even if the last field is, e.g. an int. The padding added for
2167 // bases is 1 byte. The padding added between vbases depends on the alignment
2168 // of the object but is at least 4 bytes (in both 32 and 64 bit modes).
2169 // * There is no concept of non-virtual alignment, non-virtual alignment and
2170 // alignment are always identical.
2171 // * There is a distinction between alignment and required alignment.
2172 // __declspec(align) changes the required alignment of a struct. This
2173 // alignment is _always_ obeyed, even in the presence of #pragma pack. A
2174 // record inherits required alignment from all of its fields and bases.
2175 // * __declspec(align) on bitfields has the effect of changing the bitfield's
2176 // alignment instead of its required alignment. This is the only known way
2177 // to make the alignment of a struct bigger than 8. Interestingly enough
2178 // this alignment is also immune to the effects of #pragma pack and can be
2179 // used to create structures with large alignment under #pragma pack.
2180 // However, because it does not impact required alignment, such a structure,
2181 // when used as a field or base, will not be aligned if #pragma pack is
2182 // still active at the time of use.
2183 //
2184 // Known incompatibilities:
2185 // * all: #pragma pack between fields in a record
2186 // * 2010 and back: If the last field in a record is a bitfield, every object
2187 // laid out after the record will have extra padding inserted before it. The
2188 // extra padding will have size equal to the size of the storage class of the
2189 // bitfield. 0 sized bitfields don't exhibit this behavior and the extra
2190 // padding can be avoided by adding a 0 sized bitfield after the non-zero-
2191 // sized bitfield.
2192 // * 2012 and back: In 64-bit mode, if the alignment of a record is 16 or
2193 // greater due to __declspec(align()) then a second layout phase occurs after
2194 // The locations of the vf and vb pointers are known. This layout phase
2195 // suffers from the "last field is a bitfield" bug in 2010 and results in
2196 // _every_ field getting padding put in front of it, potentially including the
2197 // vfptr, leaving the vfprt at a non-zero location which results in a fault if
2198 // anything tries to read the vftbl. The second layout phase also treats
2199 // bitfields as separate entities and gives them each storage rather than
2200 // packing them. Additionally, because this phase appears to perform a
2201 // (an unstable) sort on the members before laying them out and because merged
2202 // bitfields have the same address, the bitfields end up in whatever order
2203 // the sort left them in, a behavior we could never hope to replicate.
2204 
2205 namespace {
2206 struct MicrosoftRecordLayoutBuilder {
2207  struct ElementInfo {
2208  CharUnits Size;
2209  CharUnits Alignment;
2210  };
2211  typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsetsMapTy;
2212  MicrosoftRecordLayoutBuilder(const ASTContext &Context) : Context(Context) {}
2213 private:
2214  MicrosoftRecordLayoutBuilder(const MicrosoftRecordLayoutBuilder &) = delete;
2215  void operator=(const MicrosoftRecordLayoutBuilder &) = delete;
2216 public:
2217  void layout(const RecordDecl *RD);
2218  void cxxLayout(const CXXRecordDecl *RD);
2219  /// \brief Initializes size and alignment and honors some flags.
2220  void initializeLayout(const RecordDecl *RD);
2221  /// \brief Initialized C++ layout, compute alignment and virtual alignment and
2222  /// existence of vfptrs and vbptrs. Alignment is needed before the vfptr is
2223  /// laid out.
2224  void initializeCXXLayout(const CXXRecordDecl *RD);
2225  void layoutNonVirtualBases(const CXXRecordDecl *RD);
2226  void layoutNonVirtualBase(const CXXRecordDecl *BaseDecl,
2227  const ASTRecordLayout &BaseLayout,
2228  const ASTRecordLayout *&PreviousBaseLayout);
2229  void injectVFPtr(const CXXRecordDecl *RD);
2230  void injectVBPtr(const CXXRecordDecl *RD);
2231  /// \brief Lays out the fields of the record. Also rounds size up to
2232  /// alignment.
2233  void layoutFields(const RecordDecl *RD);
2234  void layoutField(const FieldDecl *FD);
2235  void layoutBitField(const FieldDecl *FD);
2236  /// \brief Lays out a single zero-width bit-field in the record and handles
2237  /// special cases associated with zero-width bit-fields.
2238  void layoutZeroWidthBitField(const FieldDecl *FD);
2239  void layoutVirtualBases(const CXXRecordDecl *RD);
2240  void finalizeLayout(const RecordDecl *RD);
2241  /// \brief Gets the size and alignment of a base taking pragma pack and
2242  /// __declspec(align) into account.
2243  ElementInfo getAdjustedElementInfo(const ASTRecordLayout &Layout);
2244  /// \brief Gets the size and alignment of a field taking pragma pack and
2245  /// __declspec(align) into account. It also updates RequiredAlignment as a
2246  /// side effect because it is most convenient to do so here.
2247  ElementInfo getAdjustedElementInfo(const FieldDecl *FD);
2248  /// \brief Places a field at an offset in CharUnits.
2249  void placeFieldAtOffset(CharUnits FieldOffset) {
2250  FieldOffsets.push_back(Context.toBits(FieldOffset));
2251  }
2252  /// \brief Places a bitfield at a bit offset.
2253  void placeFieldAtBitOffset(uint64_t FieldOffset) {
2254  FieldOffsets.push_back(FieldOffset);
2255  }
2256  /// \brief Compute the set of virtual bases for which vtordisps are required.
2257  void computeVtorDispSet(
2258  llvm::SmallPtrSetImpl<const CXXRecordDecl *> &HasVtorDispSet,
2259  const CXXRecordDecl *RD) const;
2260  const ASTContext &Context;
2261  /// \brief The size of the record being laid out.
2262  CharUnits Size;
2263  /// \brief The non-virtual size of the record layout.
2264  CharUnits NonVirtualSize;
2265  /// \brief The data size of the record layout.
2266  CharUnits DataSize;
2267  /// \brief The current alignment of the record layout.
2268  CharUnits Alignment;
2269  /// \brief The maximum allowed field alignment. This is set by #pragma pack.
2270  CharUnits MaxFieldAlignment;
2271  /// \brief The alignment that this record must obey. This is imposed by
2272  /// __declspec(align()) on the record itself or one of its fields or bases.
2273  CharUnits RequiredAlignment;
2274  /// \brief The size of the allocation of the currently active bitfield.
2275  /// This value isn't meaningful unless LastFieldIsNonZeroWidthBitfield
2276  /// is true.
2277  CharUnits CurrentBitfieldSize;
2278  /// \brief Offset to the virtual base table pointer (if one exists).
2279  CharUnits VBPtrOffset;
2280  /// \brief Minimum record size possible.
2281  CharUnits MinEmptyStructSize;
2282  /// \brief The size and alignment info of a pointer.
2283  ElementInfo PointerInfo;
2284  /// \brief The primary base class (if one exists).
2285  const CXXRecordDecl *PrimaryBase;
2286  /// \brief The class we share our vb-pointer with.
2287  const CXXRecordDecl *SharedVBPtrBase;
2288  /// \brief The collection of field offsets.
2289  SmallVector<uint64_t, 16> FieldOffsets;
2290  /// \brief Base classes and their offsets in the record.
2291  BaseOffsetsMapTy Bases;
2292  /// \brief virtual base classes and their offsets in the record.
2294  /// \brief The number of remaining bits in our last bitfield allocation.
2295  /// This value isn't meaningful unless LastFieldIsNonZeroWidthBitfield is
2296  /// true.
2297  unsigned RemainingBitsInField;
2298  bool IsUnion : 1;
2299  /// \brief True if the last field laid out was a bitfield and was not 0
2300  /// width.
2301  bool LastFieldIsNonZeroWidthBitfield : 1;
2302  /// \brief True if the class has its own vftable pointer.
2303  bool HasOwnVFPtr : 1;
2304  /// \brief True if the class has a vbtable pointer.
2305  bool HasVBPtr : 1;
2306  /// \brief True if the last sub-object within the type is zero sized or the
2307  /// object itself is zero sized. This *does not* count members that are not
2308  /// records. Only used for MS-ABI.
2309  bool EndsWithZeroSizedObject : 1;
2310  /// \brief True if this class is zero sized or first base is zero sized or
2311  /// has this property. Only used for MS-ABI.
2312  bool LeadsWithZeroSizedBase : 1;
2313 
2314  /// \brief True if the external AST source provided a layout for this record.
2315  bool UseExternalLayout : 1;
2316 
2317  /// \brief The layout provided by the external AST source. Only active if
2318  /// UseExternalLayout is true.
2319  ExternalLayout External;
2320 };
2321 } // namespace
2322 
2323 MicrosoftRecordLayoutBuilder::ElementInfo
2324 MicrosoftRecordLayoutBuilder::getAdjustedElementInfo(
2325  const ASTRecordLayout &Layout) {
2326  ElementInfo Info;
2327  Info.Alignment = Layout.getAlignment();
2328  // Respect pragma pack.
2329  if (!MaxFieldAlignment.isZero())
2330  Info.Alignment = std::min(Info.Alignment, MaxFieldAlignment);
2331  // Track zero-sized subobjects here where it's already available.
2332  EndsWithZeroSizedObject = Layout.hasZeroSizedSubObject();
2333  // Respect required alignment, this is necessary because we may have adjusted
2334  // the alignment in the case of pragam pack. Note that the required alignment
2335  // doesn't actually apply to the struct alignment at this point.
2336  Alignment = std::max(Alignment, Info.Alignment);
2337  RequiredAlignment = std::max(RequiredAlignment, Layout.getRequiredAlignment());
2338  Info.Alignment = std::max(Info.Alignment, Layout.getRequiredAlignment());
2339  Info.Size = Layout.getNonVirtualSize();
2340  return Info;
2341 }
2342 
2343 MicrosoftRecordLayoutBuilder::ElementInfo
2344 MicrosoftRecordLayoutBuilder::getAdjustedElementInfo(
2345  const FieldDecl *FD) {
2346  // Get the alignment of the field type's natural alignment, ignore any
2347  // alignment attributes.
2348  ElementInfo Info;
2349  std::tie(Info.Size, Info.Alignment) =
2351  // Respect align attributes on the field.
2352  CharUnits FieldRequiredAlignment =
2354  // Respect align attributes on the type.
2355  if (Context.isAlignmentRequired(FD->getType()))
2356  FieldRequiredAlignment = std::max(
2357  Context.getTypeAlignInChars(FD->getType()), FieldRequiredAlignment);
2358  // Respect attributes applied to subobjects of the field.
2359  if (FD->isBitField())
2360  // For some reason __declspec align impacts alignment rather than required
2361  // alignment when it is applied to bitfields.
2362  Info.Alignment = std::max(Info.Alignment, FieldRequiredAlignment);
2363  else {
2364  if (auto RT =
2366  auto const &Layout = Context.getASTRecordLayout(RT->getDecl());
2367  EndsWithZeroSizedObject = Layout.hasZeroSizedSubObject();
2368  FieldRequiredAlignment = std::max(FieldRequiredAlignment,
2369  Layout.getRequiredAlignment());
2370  }
2371  // Capture required alignment as a side-effect.
2372  RequiredAlignment = std::max(RequiredAlignment, FieldRequiredAlignment);
2373  }
2374  // Respect pragma pack, attribute pack and declspec align
2375  if (!MaxFieldAlignment.isZero())
2376  Info.Alignment = std::min(Info.Alignment, MaxFieldAlignment);
2377  if (FD->hasAttr<PackedAttr>())
2378  Info.Alignment = CharUnits::One();
2379  Info.Alignment = std::max(Info.Alignment, FieldRequiredAlignment);
2380  return Info;
2381 }
2382 
2383 void MicrosoftRecordLayoutBuilder::layout(const RecordDecl *RD) {
2384  // For C record layout, zero-sized records always have size 4.
2385  MinEmptyStructSize = CharUnits::fromQuantity(4);
2386  initializeLayout(RD);
2387  layoutFields(RD);
2388  DataSize = Size = Size.RoundUpToAlignment(Alignment);
2389  RequiredAlignment = std::max(
2390  RequiredAlignment, Context.toCharUnitsFromBits(RD->getMaxAlignment()));
2391  finalizeLayout(RD);
2392 }
2393 
2394 void MicrosoftRecordLayoutBuilder::cxxLayout(const CXXRecordDecl *RD) {
2395  // The C++ standard says that empty structs have size 1.
2396  MinEmptyStructSize = CharUnits::One();
2397  initializeLayout(RD);
2398  initializeCXXLayout(RD);
2399  layoutNonVirtualBases(RD);
2400  layoutFields(RD);
2401  injectVBPtr(RD);
2402  injectVFPtr(RD);
2403  if (HasOwnVFPtr || (HasVBPtr && !SharedVBPtrBase))
2404  Alignment = std::max(Alignment, PointerInfo.Alignment);
2405  auto RoundingAlignment = Alignment;
2406  if (!MaxFieldAlignment.isZero())
2407  RoundingAlignment = std::min(RoundingAlignment, MaxFieldAlignment);
2408  NonVirtualSize = Size = Size.RoundUpToAlignment(RoundingAlignment);
2409  RequiredAlignment = std::max(
2410  RequiredAlignment, Context.toCharUnitsFromBits(RD->getMaxAlignment()));
2411  layoutVirtualBases(RD);
2412  finalizeLayout(RD);
2413 }
2414 
2415 void MicrosoftRecordLayoutBuilder::initializeLayout(const RecordDecl *RD) {
2416  IsUnion = RD->isUnion();
2417  Size = CharUnits::Zero();
2418  Alignment = CharUnits::One();
2419  // In 64-bit mode we always perform an alignment step after laying out vbases.
2420  // In 32-bit mode we do not. The check to see if we need to perform alignment
2421  // checks the RequiredAlignment field and performs alignment if it isn't 0.
2422  RequiredAlignment = Context.getTargetInfo().getTriple().isArch64Bit()
2423  ? CharUnits::One()
2424  : CharUnits::Zero();
2425  // Compute the maximum field alignment.
2426  MaxFieldAlignment = CharUnits::Zero();
2427  // Honor the default struct packing maximum alignment flag.
2428  if (unsigned DefaultMaxFieldAlignment = Context.getLangOpts().PackStruct)
2429  MaxFieldAlignment = CharUnits::fromQuantity(DefaultMaxFieldAlignment);
2430  // Honor the packing attribute. The MS-ABI ignores pragma pack if its larger
2431  // than the pointer size.
2432  if (const MaxFieldAlignmentAttr *MFAA = RD->getAttr<MaxFieldAlignmentAttr>()){
2433  unsigned PackedAlignment = MFAA->getAlignment();
2434  if (PackedAlignment <= Context.getTargetInfo().getPointerWidth(0))
2435  MaxFieldAlignment = Context.toCharUnitsFromBits(PackedAlignment);
2436  }
2437  // Packed attribute forces max field alignment to be 1.
2438  if (RD->hasAttr<PackedAttr>())
2439  MaxFieldAlignment = CharUnits::One();
2440 
2441  // Try to respect the external layout if present.
2442  UseExternalLayout = false;
2444  UseExternalLayout = Source->layoutRecordType(
2445  RD, External.Size, External.Align, External.FieldOffsets,
2446  External.BaseOffsets, External.VirtualBaseOffsets);
2447 }
2448 
2449 void
2450 MicrosoftRecordLayoutBuilder::initializeCXXLayout(const CXXRecordDecl *RD) {
2451  EndsWithZeroSizedObject = false;
2452  LeadsWithZeroSizedBase = false;
2453  HasOwnVFPtr = false;
2454  HasVBPtr = false;
2455  PrimaryBase = nullptr;
2456  SharedVBPtrBase = nullptr;
2457  // Calculate pointer size and alignment. These are used for vfptr and vbprt
2458  // injection.
2459  PointerInfo.Size =
2461  PointerInfo.Alignment =
2463  // Respect pragma pack.
2464  if (!MaxFieldAlignment.isZero())
2465  PointerInfo.Alignment = std::min(PointerInfo.Alignment, MaxFieldAlignment);
2466 }
2467 
2468 void
2469 MicrosoftRecordLayoutBuilder::layoutNonVirtualBases(const CXXRecordDecl *RD) {
2470  // The MS-ABI lays out all bases that contain leading vfptrs before it lays
2471  // out any bases that do not contain vfptrs. We implement this as two passes
2472  // over the bases. This approach guarantees that the primary base is laid out
2473  // first. We use these passes to calculate some additional aggregated
2474  // information about the bases, such as reqruied alignment and the presence of
2475  // zero sized members.
2476  const ASTRecordLayout *PreviousBaseLayout = nullptr;
2477  // Iterate through the bases and lay out the non-virtual ones.
2478  for (const CXXBaseSpecifier &Base : RD->bases()) {
2479  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2480  const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2481  // Mark and skip virtual bases.
2482  if (Base.isVirtual()) {
2483  HasVBPtr = true;
2484  continue;
2485  }
2486  // Check fo a base to share a VBPtr with.
2487  if (!SharedVBPtrBase && BaseLayout.hasVBPtr()) {
2488  SharedVBPtrBase = BaseDecl;
2489  HasVBPtr = true;
2490  }
2491  // Only lay out bases with extendable VFPtrs on the first pass.
2492  if (!BaseLayout.hasExtendableVFPtr())
2493  continue;
2494  // If we don't have a primary base, this one qualifies.
2495  if (!PrimaryBase) {
2496  PrimaryBase = BaseDecl;
2497  LeadsWithZeroSizedBase = BaseLayout.leadsWithZeroSizedBase();
2498  }
2499  // Lay out the base.
2500  layoutNonVirtualBase(BaseDecl, BaseLayout, PreviousBaseLayout);
2501  }
2502  // Figure out if we need a fresh VFPtr for this class.
2503  if (!PrimaryBase && RD->isDynamicClass())
2505  e = RD->method_end();
2506  !HasOwnVFPtr && i != e; ++i)
2507  HasOwnVFPtr = i->isVirtual() && i->size_overridden_methods() == 0;
2508  // If we don't have a primary base then we have a leading object that could
2509  // itself lead with a zero-sized object, something we track.
2510  bool CheckLeadingLayout = !PrimaryBase;
2511  // Iterate through the bases and lay out the non-virtual ones.
2512  for (const CXXBaseSpecifier &Base : RD->bases()) {
2513  if (Base.isVirtual())
2514  continue;
2515  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2516  const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2517  // Only lay out bases without extendable VFPtrs on the second pass.
2518  if (BaseLayout.hasExtendableVFPtr()) {
2519  VBPtrOffset = Bases[BaseDecl] + BaseLayout.getNonVirtualSize();
2520  continue;
2521  }
2522  // If this is the first layout, check to see if it leads with a zero sized
2523  // object. If it does, so do we.
2524  if (CheckLeadingLayout) {
2525  CheckLeadingLayout = false;
2526  LeadsWithZeroSizedBase = BaseLayout.leadsWithZeroSizedBase();
2527  }
2528  // Lay out the base.
2529  layoutNonVirtualBase(BaseDecl, BaseLayout, PreviousBaseLayout);
2530  VBPtrOffset = Bases[BaseDecl] + BaseLayout.getNonVirtualSize();
2531  }
2532  // Set our VBPtroffset if we know it at this point.
2533  if (!HasVBPtr)
2534  VBPtrOffset = CharUnits::fromQuantity(-1);
2535  else if (SharedVBPtrBase) {
2536  const ASTRecordLayout &Layout = Context.getASTRecordLayout(SharedVBPtrBase);
2537  VBPtrOffset = Bases[SharedVBPtrBase] + Layout.getVBPtrOffset();
2538  }
2539 }
2540 
2541 void MicrosoftRecordLayoutBuilder::layoutNonVirtualBase(
2542  const CXXRecordDecl *BaseDecl,
2543  const ASTRecordLayout &BaseLayout,
2544  const ASTRecordLayout *&PreviousBaseLayout) {
2545  // Insert padding between two bases if the left first one is zero sized or
2546  // contains a zero sized subobject and the right is zero sized or one leads
2547  // with a zero sized base.
2548  if (PreviousBaseLayout && PreviousBaseLayout->hasZeroSizedSubObject() &&
2549  BaseLayout.leadsWithZeroSizedBase())
2550  Size++;
2551  ElementInfo Info = getAdjustedElementInfo(BaseLayout);
2552  CharUnits BaseOffset;
2553 
2554  // Respect the external AST source base offset, if present.
2555  bool FoundBase = false;
2556  if (UseExternalLayout) {
2557  FoundBase = External.getExternalNVBaseOffset(BaseDecl, BaseOffset);
2558  if (FoundBase)
2559  assert(BaseOffset >= Size && "base offset already allocated");
2560  }
2561 
2562  if (!FoundBase)
2563  BaseOffset = Size.RoundUpToAlignment(Info.Alignment);
2564  Bases.insert(std::make_pair(BaseDecl, BaseOffset));
2565  Size = BaseOffset + BaseLayout.getNonVirtualSize();
2566  PreviousBaseLayout = &BaseLayout;
2567 }
2568 
2569 void MicrosoftRecordLayoutBuilder::layoutFields(const RecordDecl *RD) {
2570  LastFieldIsNonZeroWidthBitfield = false;
2571  for (const FieldDecl *Field : RD->fields())
2572  layoutField(Field);
2573 }
2574 
2575 void MicrosoftRecordLayoutBuilder::layoutField(const FieldDecl *FD) {
2576  if (FD->isBitField()) {
2577  layoutBitField(FD);
2578  return;
2579  }
2580  LastFieldIsNonZeroWidthBitfield = false;
2581  ElementInfo Info = getAdjustedElementInfo(FD);
2582  Alignment = std::max(Alignment, Info.Alignment);
2583  if (IsUnion) {
2584  placeFieldAtOffset(CharUnits::Zero());
2585  Size = std::max(Size, Info.Size);
2586  } else {
2587  CharUnits FieldOffset;
2588  if (UseExternalLayout) {
2589  FieldOffset =
2590  Context.toCharUnitsFromBits(External.getExternalFieldOffset(FD));
2591  assert(FieldOffset >= Size && "field offset already allocated");
2592  } else {
2593  FieldOffset = Size.RoundUpToAlignment(Info.Alignment);
2594  }
2595  placeFieldAtOffset(FieldOffset);
2596  Size = FieldOffset + Info.Size;
2597  }
2598 }
2599 
2600 void MicrosoftRecordLayoutBuilder::layoutBitField(const FieldDecl *FD) {
2601  unsigned Width = FD->getBitWidthValue(Context);
2602  if (Width == 0) {
2603  layoutZeroWidthBitField(FD);
2604  return;
2605  }
2606  ElementInfo Info = getAdjustedElementInfo(FD);
2607  // Clamp the bitfield to a containable size for the sake of being able
2608  // to lay them out. Sema will throw an error.
2609  if (Width > Context.toBits(Info.Size))
2610  Width = Context.toBits(Info.Size);
2611  // Check to see if this bitfield fits into an existing allocation. Note:
2612  // MSVC refuses to pack bitfields of formal types with different sizes
2613  // into the same allocation.
2614  if (!IsUnion && LastFieldIsNonZeroWidthBitfield &&
2615  CurrentBitfieldSize == Info.Size && Width <= RemainingBitsInField) {
2616  placeFieldAtBitOffset(Context.toBits(Size) - RemainingBitsInField);
2617  RemainingBitsInField -= Width;
2618  return;
2619  }
2620  LastFieldIsNonZeroWidthBitfield = true;
2621  CurrentBitfieldSize = Info.Size;
2622  if (IsUnion) {
2623  placeFieldAtOffset(CharUnits::Zero());
2624  Size = std::max(Size, Info.Size);
2625  // TODO: Add a Sema warning that MS ignores bitfield alignment in unions.
2626  } else {
2627  // Allocate a new block of memory and place the bitfield in it.
2628  CharUnits FieldOffset = Size.RoundUpToAlignment(Info.Alignment);
2629  placeFieldAtOffset(FieldOffset);
2630  Size = FieldOffset + Info.Size;
2631  Alignment = std::max(Alignment, Info.Alignment);
2632  RemainingBitsInField = Context.toBits(Info.Size) - Width;
2633  }
2634 }
2635 
2636 void
2637 MicrosoftRecordLayoutBuilder::layoutZeroWidthBitField(const FieldDecl *FD) {
2638  // Zero-width bitfields are ignored unless they follow a non-zero-width
2639  // bitfield.
2640  if (!LastFieldIsNonZeroWidthBitfield) {
2641  placeFieldAtOffset(IsUnion ? CharUnits::Zero() : Size);
2642  // TODO: Add a Sema warning that MS ignores alignment for zero
2643  // sized bitfields that occur after zero-size bitfields or non-bitfields.
2644  return;
2645  }
2646  LastFieldIsNonZeroWidthBitfield = false;
2647  ElementInfo Info = getAdjustedElementInfo(FD);
2648  if (IsUnion) {
2649  placeFieldAtOffset(CharUnits::Zero());
2650  Size = std::max(Size, Info.Size);
2651  // TODO: Add a Sema warning that MS ignores bitfield alignment in unions.
2652  } else {
2653  // Round up the current record size to the field's alignment boundary.
2654  CharUnits FieldOffset = Size.RoundUpToAlignment(Info.Alignment);
2655  placeFieldAtOffset(FieldOffset);
2656  Size = FieldOffset;
2657  Alignment = std::max(Alignment, Info.Alignment);
2658  }
2659 }
2660 
2661 void MicrosoftRecordLayoutBuilder::injectVBPtr(const CXXRecordDecl *RD) {
2662  if (!HasVBPtr || SharedVBPtrBase)
2663  return;
2664  // Inject the VBPointer at the injection site.
2665  CharUnits InjectionSite = VBPtrOffset;
2666  // But before we do, make sure it's properly aligned.
2667  VBPtrOffset = VBPtrOffset.RoundUpToAlignment(PointerInfo.Alignment);
2668  // Shift everything after the vbptr down, unless we're using an external
2669  // layout.
2670  if (UseExternalLayout)
2671  return;
2672  // Determine where the first field should be laid out after the vbptr.
2673  CharUnits FieldStart = VBPtrOffset + PointerInfo.Size;
2674  // Make sure that the amount we push the fields back by is a multiple of the
2675  // alignment.
2676  CharUnits Offset = (FieldStart - InjectionSite).RoundUpToAlignment(
2677  std::max(RequiredAlignment, Alignment));
2678  Size += Offset;
2679  for (uint64_t &FieldOffset : FieldOffsets)
2680  FieldOffset += Context.toBits(Offset);
2681  for (BaseOffsetsMapTy::value_type &Base : Bases)
2682  if (Base.second >= InjectionSite)
2683  Base.second += Offset;
2684 }
2685 
2686 void MicrosoftRecordLayoutBuilder::injectVFPtr(const CXXRecordDecl *RD) {
2687  if (!HasOwnVFPtr)
2688  return;
2689  // Make sure that the amount we push the struct back by is a multiple of the
2690  // alignment.
2691  CharUnits Offset = PointerInfo.Size.RoundUpToAlignment(
2692  std::max(RequiredAlignment, Alignment));
2693  // Push back the vbptr, but increase the size of the object and push back
2694  // regular fields by the offset only if not using external record layout.
2695  if (HasVBPtr)
2696  VBPtrOffset += Offset;
2697 
2698  if (UseExternalLayout)
2699  return;
2700 
2701  Size += Offset;
2702 
2703  // If we're using an external layout, the fields offsets have already
2704  // accounted for this adjustment.
2705  for (uint64_t &FieldOffset : FieldOffsets)
2706  FieldOffset += Context.toBits(Offset);
2707  for (BaseOffsetsMapTy::value_type &Base : Bases)
2708  Base.second += Offset;
2709 }
2710 
2711 void MicrosoftRecordLayoutBuilder::layoutVirtualBases(const CXXRecordDecl *RD) {
2712  if (!HasVBPtr)
2713  return;
2714  // Vtordisps are always 4 bytes (even in 64-bit mode)
2715  CharUnits VtorDispSize = CharUnits::fromQuantity(4);
2716  CharUnits VtorDispAlignment = VtorDispSize;
2717  // vtordisps respect pragma pack.
2718  if (!MaxFieldAlignment.isZero())
2719  VtorDispAlignment = std::min(VtorDispAlignment, MaxFieldAlignment);
2720  // The alignment of the vtordisp is at least the required alignment of the
2721  // entire record. This requirement may be present to support vtordisp
2722  // injection.
2723  for (const CXXBaseSpecifier &VBase : RD->vbases()) {
2724  const CXXRecordDecl *BaseDecl = VBase.getType()->getAsCXXRecordDecl();
2725  const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2726  RequiredAlignment =
2727  std::max(RequiredAlignment, BaseLayout.getRequiredAlignment());
2728  }
2729  VtorDispAlignment = std::max(VtorDispAlignment, RequiredAlignment);
2730  // Compute the vtordisp set.
2731  llvm::SmallPtrSet<const CXXRecordDecl *, 2> HasVtorDispSet;
2732  computeVtorDispSet(HasVtorDispSet, RD);
2733  // Iterate through the virtual bases and lay them out.
2734  const ASTRecordLayout *PreviousBaseLayout = nullptr;
2735  for (const CXXBaseSpecifier &VBase : RD->vbases()) {
2736  const CXXRecordDecl *BaseDecl = VBase.getType()->getAsCXXRecordDecl();
2737  const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2738  bool HasVtordisp = HasVtorDispSet.count(BaseDecl) > 0;
2739  // Insert padding between two bases if the left first one is zero sized or
2740  // contains a zero sized subobject and the right is zero sized or one leads
2741  // with a zero sized base. The padding between virtual bases is 4
2742  // bytes (in both 32 and 64 bits modes) and always involves rounding up to
2743  // the required alignment, we don't know why.
2744  if ((PreviousBaseLayout && PreviousBaseLayout->hasZeroSizedSubObject() &&
2745  BaseLayout.leadsWithZeroSizedBase()) || HasVtordisp) {
2746  Size = Size.RoundUpToAlignment(VtorDispAlignment) + VtorDispSize;
2747  Alignment = std::max(VtorDispAlignment, Alignment);
2748  }
2749  // Insert the virtual base.
2750  ElementInfo Info = getAdjustedElementInfo(BaseLayout);
2751  CharUnits BaseOffset;
2752 
2753  // Respect the external AST source base offset, if present.
2754  bool FoundBase = false;
2755  if (UseExternalLayout) {
2756  FoundBase = External.getExternalVBaseOffset(BaseDecl, BaseOffset);
2757  if (FoundBase)
2758  assert(BaseOffset >= Size && "base offset already allocated");
2759  }
2760  if (!FoundBase)
2761  BaseOffset = Size.RoundUpToAlignment(Info.Alignment);
2762 
2763  VBases.insert(std::make_pair(BaseDecl,
2764  ASTRecordLayout::VBaseInfo(BaseOffset, HasVtordisp)));
2765  Size = BaseOffset + BaseLayout.getNonVirtualSize();
2766  PreviousBaseLayout = &BaseLayout;
2767  }
2768 }
2769 
2770 void MicrosoftRecordLayoutBuilder::finalizeLayout(const RecordDecl *RD) {
2771  // Respect required alignment. Note that in 32-bit mode Required alignment
2772  // may be 0 and cause size not to be updated.
2773  DataSize = Size;
2774  if (!RequiredAlignment.isZero()) {
2775  Alignment = std::max(Alignment, RequiredAlignment);
2776  auto RoundingAlignment = Alignment;
2777  if (!MaxFieldAlignment.isZero())
2778  RoundingAlignment = std::min(RoundingAlignment, MaxFieldAlignment);
2779  RoundingAlignment = std::max(RoundingAlignment, RequiredAlignment);
2780  Size = Size.RoundUpToAlignment(RoundingAlignment);
2781  }
2782  if (Size.isZero()) {
2783  EndsWithZeroSizedObject = true;
2784  LeadsWithZeroSizedBase = true;
2785  // Zero-sized structures have size equal to their alignment if a
2786  // __declspec(align) came into play.
2787  if (RequiredAlignment >= MinEmptyStructSize)
2788  Size = Alignment;
2789  else
2790  Size = MinEmptyStructSize;
2791  }
2792 
2793  if (UseExternalLayout) {
2794  Size = Context.toCharUnitsFromBits(External.Size);
2795  if (External.Align)
2796  Alignment = Context.toCharUnitsFromBits(External.Align);
2797  }
2798 }
2799 
2800 // Recursively walks the non-virtual bases of a class and determines if any of
2801 // them are in the bases with overridden methods set.
2802 static bool
2803 RequiresVtordisp(const llvm::SmallPtrSetImpl<const CXXRecordDecl *> &
2804  BasesWithOverriddenMethods,
2805  const CXXRecordDecl *RD) {
2806  if (BasesWithOverriddenMethods.count(RD))
2807  return true;
2808  // If any of a virtual bases non-virtual bases (recursively) requires a
2809  // vtordisp than so does this virtual base.
2810  for (const CXXBaseSpecifier &Base : RD->bases())
2811  if (!Base.isVirtual() &&
2812  RequiresVtordisp(BasesWithOverriddenMethods,
2813  Base.getType()->getAsCXXRecordDecl()))
2814  return true;
2815  return false;
2816 }
2817 
2818 void MicrosoftRecordLayoutBuilder::computeVtorDispSet(
2819  llvm::SmallPtrSetImpl<const CXXRecordDecl *> &HasVtordispSet,
2820  const CXXRecordDecl *RD) const {
2821  // /vd2 or #pragma vtordisp(2): Always use vtordisps for virtual bases with
2822  // vftables.
2823  if (RD->getMSVtorDispMode() == MSVtorDispAttr::ForVFTable) {
2824  for (const CXXBaseSpecifier &Base : RD->vbases()) {
2825  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2826  const ASTRecordLayout &Layout = Context.getASTRecordLayout(BaseDecl);
2827  if (Layout.hasExtendableVFPtr())
2828  HasVtordispSet.insert(BaseDecl);
2829  }
2830  return;
2831  }
2832 
2833  // If any of our bases need a vtordisp for this type, so do we. Check our
2834  // direct bases for vtordisp requirements.
2835  for (const CXXBaseSpecifier &Base : RD->bases()) {
2836  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2837  const ASTRecordLayout &Layout = Context.getASTRecordLayout(BaseDecl);
2838  for (const auto &bi : Layout.getVBaseOffsetsMap())
2839  if (bi.second.hasVtorDisp())
2840  HasVtordispSet.insert(bi.first);
2841  }
2842  // We don't introduce any additional vtordisps if either:
2843  // * A user declared constructor or destructor aren't declared.
2844  // * #pragma vtordisp(0) or the /vd0 flag are in use.
2845  if ((!RD->hasUserDeclaredConstructor() && !RD->hasUserDeclaredDestructor()) ||
2846  RD->getMSVtorDispMode() == MSVtorDispAttr::Never)
2847  return;
2848  // /vd1 or #pragma vtordisp(1): Try to guess based on whether we think it's
2849  // possible for a partially constructed object with virtual base overrides to
2850  // escape a non-trivial constructor.
2851  assert(RD->getMSVtorDispMode() == MSVtorDispAttr::ForVBaseOverride);
2852  // Compute a set of base classes which define methods we override. A virtual
2853  // base in this set will require a vtordisp. A virtual base that transitively
2854  // contains one of these bases as a non-virtual base will also require a
2855  // vtordisp.
2856  llvm::SmallPtrSet<const CXXMethodDecl *, 8> Work;
2857  llvm::SmallPtrSet<const CXXRecordDecl *, 2> BasesWithOverriddenMethods;
2858  // Seed the working set with our non-destructor, non-pure virtual methods.
2859  for (const CXXMethodDecl *MD : RD->methods())
2860  if (MD->isVirtual() && !isa<CXXDestructorDecl>(MD) && !MD->isPure())
2861  Work.insert(MD);
2862  while (!Work.empty()) {
2863  const CXXMethodDecl *MD = *Work.begin();
2865  e = MD->end_overridden_methods();
2866  // If a virtual method has no-overrides it lives in its parent's vtable.
2867  if (i == e)
2868  BasesWithOverriddenMethods.insert(MD->getParent());
2869  else
2870  Work.insert(i, e);
2871  // We've finished processing this element, remove it from the working set.
2872  Work.erase(MD);
2873  }
2874  // For each of our virtual bases, check if it is in the set of overridden
2875  // bases or if it transitively contains a non-virtual base that is.
2876  for (const CXXBaseSpecifier &Base : RD->vbases()) {
2877  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2878  if (!HasVtordispSet.count(BaseDecl) &&
2879  RequiresVtordisp(BasesWithOverriddenMethods, BaseDecl))
2880  HasVtordispSet.insert(BaseDecl);
2881  }
2882 }
2883 
2884 /// getASTRecordLayout - Get or compute information about the layout of the
2885 /// specified record (struct/union/class), which indicates its size and field
2886 /// position information.
2887 const ASTRecordLayout &
2889  // These asserts test different things. A record has a definition
2890  // as soon as we begin to parse the definition. That definition is
2891  // not a complete definition (which is what isDefinition() tests)
2892  // until we *finish* parsing the definition.
2893 
2894  if (D->hasExternalLexicalStorage() && !D->getDefinition())
2895  getExternalSource()->CompleteType(const_cast<RecordDecl*>(D));
2896 
2897  D = D->getDefinition();
2898  assert(D && "Cannot get layout of forward declarations!");
2899  assert(!D->isInvalidDecl() && "Cannot get layout of invalid decl!");
2900  assert(D->isCompleteDefinition() && "Cannot layout type before complete!");
2901 
2902  // Look up this layout, if already laid out, return what we have.
2903  // Note that we can't save a reference to the entry because this function
2904  // is recursive.
2905  const ASTRecordLayout *Entry = ASTRecordLayouts[D];
2906  if (Entry) return *Entry;
2907 
2908  const ASTRecordLayout *NewEntry = nullptr;
2909 
2910  if (isMsLayout(*this)) {
2911  MicrosoftRecordLayoutBuilder Builder(*this);
2912  if (const auto *RD = dyn_cast<CXXRecordDecl>(D)) {
2913  Builder.cxxLayout(RD);
2914  NewEntry = new (*this) ASTRecordLayout(
2915  *this, Builder.Size, Builder.Alignment, Builder.RequiredAlignment,
2916  Builder.HasOwnVFPtr, Builder.HasOwnVFPtr || Builder.PrimaryBase,
2917  Builder.VBPtrOffset, Builder.NonVirtualSize,
2918  Builder.FieldOffsets.data(), Builder.FieldOffsets.size(),
2919  Builder.NonVirtualSize, Builder.Alignment, CharUnits::Zero(),
2920  Builder.PrimaryBase, false, Builder.SharedVBPtrBase,
2921  Builder.EndsWithZeroSizedObject, Builder.LeadsWithZeroSizedBase,
2922  Builder.Bases, Builder.VBases);
2923  } else {
2924  Builder.layout(D);
2925  NewEntry = new (*this) ASTRecordLayout(
2926  *this, Builder.Size, Builder.Alignment, Builder.RequiredAlignment,
2927  Builder.Size, Builder.FieldOffsets.data(),
2928  Builder.FieldOffsets.size());
2929  }
2930  } else {
2931  if (const auto *RD = dyn_cast<CXXRecordDecl>(D)) {
2932  EmptySubobjectMap EmptySubobjects(*this, RD);
2933  ItaniumRecordLayoutBuilder Builder(*this, &EmptySubobjects);
2934  Builder.Layout(RD);
2935 
2936  // In certain situations, we are allowed to lay out objects in the
2937  // tail-padding of base classes. This is ABI-dependent.
2938  // FIXME: this should be stored in the record layout.
2939  bool skipTailPadding =
2940  mustSkipTailPadding(getTargetInfo().getCXXABI(), RD);
2941 
2942  // FIXME: This should be done in FinalizeLayout.
2943  CharUnits DataSize =
2944  skipTailPadding ? Builder.getSize() : Builder.getDataSize();
2945  CharUnits NonVirtualSize =
2946  skipTailPadding ? DataSize : Builder.NonVirtualSize;
2947  NewEntry = new (*this) ASTRecordLayout(
2948  *this, Builder.getSize(), Builder.Alignment,
2949  /*RequiredAlignment : used by MS-ABI)*/
2950  Builder.Alignment, Builder.HasOwnVFPtr, RD->isDynamicClass(),
2951  CharUnits::fromQuantity(-1), DataSize, Builder.FieldOffsets.data(),
2952  Builder.FieldOffsets.size(), NonVirtualSize,
2953  Builder.NonVirtualAlignment,
2954  EmptySubobjects.SizeOfLargestEmptySubobject, Builder.PrimaryBase,
2955  Builder.PrimaryBaseIsVirtual, nullptr, false, false, Builder.Bases,
2956  Builder.VBases);
2957  } else {
2958  ItaniumRecordLayoutBuilder Builder(*this, /*EmptySubobjects=*/nullptr);
2959  Builder.Layout(D);
2960 
2961  NewEntry = new (*this) ASTRecordLayout(
2962  *this, Builder.getSize(), Builder.Alignment,
2963  /*RequiredAlignment : used by MS-ABI)*/
2964  Builder.Alignment, Builder.getSize(), Builder.FieldOffsets.data(),
2965  Builder.FieldOffsets.size());
2966  }
2967  }
2968 
2969  ASTRecordLayouts[D] = NewEntry;
2970 
2971  if (getLangOpts().DumpRecordLayouts) {
2972  llvm::outs() << "\n*** Dumping AST Record Layout\n";
2973  DumpRecordLayout(D, llvm::outs(), getLangOpts().DumpRecordLayoutsSimple);
2974  }
2975 
2976  return *NewEntry;
2977 }
2978 
2980  if (!getTargetInfo().getCXXABI().hasKeyFunctions())
2981  return nullptr;
2982 
2983  assert(RD->getDefinition() && "Cannot get key function for forward decl!");
2984  RD = cast<CXXRecordDecl>(RD->getDefinition());
2985 
2986  // Beware:
2987  // 1) computing the key function might trigger deserialization, which might
2988  // invalidate iterators into KeyFunctions
2989  // 2) 'get' on the LazyDeclPtr might also trigger deserialization and
2990  // invalidate the LazyDeclPtr within the map itself
2991  LazyDeclPtr Entry = KeyFunctions[RD];
2992  const Decl *Result =
2993  Entry ? Entry.get(getExternalSource()) : computeKeyFunction(*this, RD);
2994 
2995  // Store it back if it changed.
2996  if (Entry.isOffset() || Entry.isValid() != bool(Result))
2997  KeyFunctions[RD] = const_cast<Decl*>(Result);
2998 
2999  return cast_or_null<CXXMethodDecl>(Result);
3000 }
3001 
3003  assert(Method == Method->getFirstDecl() &&
3004  "not working with method declaration from class definition");
3005 
3006  // Look up the cache entry. Since we're working with the first
3007  // declaration, its parent must be the class definition, which is
3008  // the correct key for the KeyFunctions hash.
3009  const auto &Map = KeyFunctions;
3010  auto I = Map.find(Method->getParent());
3011 
3012  // If it's not cached, there's nothing to do.
3013  if (I == Map.end()) return;
3014 
3015  // If it is cached, check whether it's the target method, and if so,
3016  // remove it from the cache. Note, the call to 'get' might invalidate
3017  // the iterator and the LazyDeclPtr object within the map.
3018  LazyDeclPtr Ptr = I->second;
3019  if (Ptr.get(getExternalSource()) == Method) {
3020  // FIXME: remember that we did this for module / chained PCH state?
3021  KeyFunctions.erase(Method->getParent());
3022  }
3023 }
3024 
3025 static uint64_t getFieldOffset(const ASTContext &C, const FieldDecl *FD) {
3026  const ASTRecordLayout &Layout = C.getASTRecordLayout(FD->getParent());
3027  return Layout.getFieldOffset(FD->getFieldIndex());
3028 }
3029 
3030 uint64_t ASTContext::getFieldOffset(const ValueDecl *VD) const {
3031  uint64_t OffsetInBits;
3032  if (const FieldDecl *FD = dyn_cast<FieldDecl>(VD)) {
3033  OffsetInBits = ::getFieldOffset(*this, FD);
3034  } else {
3035  const IndirectFieldDecl *IFD = cast<IndirectFieldDecl>(VD);
3036 
3037  OffsetInBits = 0;
3038  for (const NamedDecl *ND : IFD->chain())
3039  OffsetInBits += ::getFieldOffset(*this, cast<FieldDecl>(ND));
3040  }
3041 
3042  return OffsetInBits;
3043 }
3044 
3045 /// getObjCLayout - Get or compute information about the layout of the
3046 /// given interface.
3047 ///
3048 /// \param Impl - If given, also include the layout of the interface's
3049 /// implementation. This may differ by including synthesized ivars.
3050 const ASTRecordLayout &
3051 ASTContext::getObjCLayout(const ObjCInterfaceDecl *D,
3052  const ObjCImplementationDecl *Impl) const {
3053  // Retrieve the definition
3054  if (D->hasExternalLexicalStorage() && !D->getDefinition())
3055  getExternalSource()->CompleteType(const_cast<ObjCInterfaceDecl*>(D));
3056  D = D->getDefinition();
3057  assert(D && D->isThisDeclarationADefinition() && "Invalid interface decl!");
3058 
3059  // Look up this layout, if already laid out, return what we have.
3060  const ObjCContainerDecl *Key =
3061  Impl ? (const ObjCContainerDecl*) Impl : (const ObjCContainerDecl*) D;
3062  if (const ASTRecordLayout *Entry = ObjCLayouts[Key])
3063  return *Entry;
3064 
3065  // Add in synthesized ivar count if laying out an implementation.
3066  if (Impl) {
3067  unsigned SynthCount = CountNonClassIvars(D);
3068  // If there aren't any sythesized ivars then reuse the interface
3069  // entry. Note we can't cache this because we simply free all
3070  // entries later; however we shouldn't look up implementations
3071  // frequently.
3072  if (SynthCount == 0)
3073  return getObjCLayout(D, nullptr);
3074  }
3075 
3076  ItaniumRecordLayoutBuilder Builder(*this, /*EmptySubobjects=*/nullptr);
3077  Builder.Layout(D);
3078 
3079  const ASTRecordLayout *NewEntry =
3080  new (*this) ASTRecordLayout(*this, Builder.getSize(),
3081  Builder.Alignment,
3082  /*RequiredAlignment : used by MS-ABI)*/
3083  Builder.Alignment,
3084  Builder.getDataSize(),
3085  Builder.FieldOffsets.data(),
3086  Builder.FieldOffsets.size());
3087 
3088  ObjCLayouts[Key] = NewEntry;
3089 
3090  return *NewEntry;
3091 }
3092 
3093 static void PrintOffset(raw_ostream &OS,
3094  CharUnits Offset, unsigned IndentLevel) {
3095  OS << llvm::format("%10" PRId64 " | ", (int64_t)Offset.getQuantity());
3096  OS.indent(IndentLevel * 2);
3097 }
3098 
3099 static void PrintBitFieldOffset(raw_ostream &OS, CharUnits Offset,
3100  unsigned Begin, unsigned Width,
3101  unsigned IndentLevel) {
3103  {
3104  llvm::raw_svector_ostream BufferOS(Buffer);
3105  BufferOS << Offset.getQuantity() << ':';
3106  if (Width == 0) {
3107  BufferOS << '-';
3108  } else {
3109  BufferOS << Begin << '-' << (Begin + Width - 1);
3110  }
3111  }
3112 
3113  OS << llvm::right_justify(Buffer, 10) << " | ";
3114  OS.indent(IndentLevel * 2);
3115 }
3116 
3117 static void PrintIndentNoOffset(raw_ostream &OS, unsigned IndentLevel) {
3118  OS << " | ";
3119  OS.indent(IndentLevel * 2);
3120 }
3121 
3122 static void DumpRecordLayout(raw_ostream &OS, const RecordDecl *RD,
3123  const ASTContext &C,
3124  CharUnits Offset,
3125  unsigned IndentLevel,
3126  const char* Description,
3127  bool PrintSizeInfo,
3128  bool IncludeVirtualBases) {
3129  const ASTRecordLayout &Layout = C.getASTRecordLayout(RD);
3130  auto CXXRD = dyn_cast<CXXRecordDecl>(RD);
3131 
3132  PrintOffset(OS, Offset, IndentLevel);
3133  OS << C.getTypeDeclType(const_cast<RecordDecl*>(RD)).getAsString();
3134  if (Description)
3135  OS << ' ' << Description;
3136  if (CXXRD && CXXRD->isEmpty())
3137  OS << " (empty)";
3138  OS << '\n';
3139 
3140  IndentLevel++;
3141 
3142  // Dump bases.
3143  if (CXXRD) {
3144  const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
3145  bool HasOwnVFPtr = Layout.hasOwnVFPtr();
3146  bool HasOwnVBPtr = Layout.hasOwnVBPtr();
3147 
3148  // Vtable pointer.
3149  if (CXXRD->isDynamicClass() && !PrimaryBase && !isMsLayout(C)) {
3150  PrintOffset(OS, Offset, IndentLevel);
3151  OS << '(' << *RD << " vtable pointer)\n";
3152  } else if (HasOwnVFPtr) {
3153  PrintOffset(OS, Offset, IndentLevel);
3154  // vfptr (for Microsoft C++ ABI)
3155  OS << '(' << *RD << " vftable pointer)\n";
3156  }
3157 
3158  // Collect nvbases.
3160  for (const CXXBaseSpecifier &Base : CXXRD->bases()) {
3161  assert(!Base.getType()->isDependentType() &&
3162  "Cannot layout class with dependent bases.");
3163  if (!Base.isVirtual())
3164  Bases.push_back(Base.getType()->getAsCXXRecordDecl());
3165  }
3166 
3167  // Sort nvbases by offset.
3168  std::stable_sort(Bases.begin(), Bases.end(),
3169  [&](const CXXRecordDecl *L, const CXXRecordDecl *R) {
3170  return Layout.getBaseClassOffset(L) < Layout.getBaseClassOffset(R);
3171  });
3172 
3173  // Dump (non-virtual) bases
3174  for (const CXXRecordDecl *Base : Bases) {
3175  CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base);
3176  DumpRecordLayout(OS, Base, C, BaseOffset, IndentLevel,
3177  Base == PrimaryBase ? "(primary base)" : "(base)",
3178  /*PrintSizeInfo=*/false,
3179  /*IncludeVirtualBases=*/false);
3180  }
3181 
3182  // vbptr (for Microsoft C++ ABI)
3183  if (HasOwnVBPtr) {
3184  PrintOffset(OS, Offset + Layout.getVBPtrOffset(), IndentLevel);
3185  OS << '(' << *RD << " vbtable pointer)\n";
3186  }
3187  }
3188 
3189  // Dump fields.
3190  uint64_t FieldNo = 0;
3191  for (RecordDecl::field_iterator I = RD->field_begin(),
3192  E = RD->field_end(); I != E; ++I, ++FieldNo) {
3193  const FieldDecl &Field = **I;
3194  uint64_t LocalFieldOffsetInBits = Layout.getFieldOffset(FieldNo);
3195  CharUnits FieldOffset =
3196  Offset + C.toCharUnitsFromBits(LocalFieldOffsetInBits);
3197 
3198  // Recursively dump fields of record type.
3199  if (auto RT = Field.getType()->getAs<RecordType>()) {
3200  DumpRecordLayout(OS, RT->getDecl(), C, FieldOffset, IndentLevel,
3201  Field.getName().data(),
3202  /*PrintSizeInfo=*/false,
3203  /*IncludeVirtualBases=*/true);
3204  continue;
3205  }
3206 
3207  if (Field.isBitField()) {
3208  uint64_t LocalFieldByteOffsetInBits = C.toBits(FieldOffset - Offset);
3209  unsigned Begin = LocalFieldOffsetInBits - LocalFieldByteOffsetInBits;
3210  unsigned Width = Field.getBitWidthValue(C);
3211  PrintBitFieldOffset(OS, FieldOffset, Begin, Width, IndentLevel);
3212  } else {
3213  PrintOffset(OS, FieldOffset, IndentLevel);
3214  }
3215  OS << Field.getType().getAsString() << ' ' << Field << '\n';
3216  }
3217 
3218  // Dump virtual bases.
3219  if (CXXRD && IncludeVirtualBases) {
3220  const ASTRecordLayout::VBaseOffsetsMapTy &VtorDisps =
3221  Layout.getVBaseOffsetsMap();
3222 
3223  for (const CXXBaseSpecifier &Base : CXXRD->vbases()) {
3224  assert(Base.isVirtual() && "Found non-virtual class!");
3225  const CXXRecordDecl *VBase = Base.getType()->getAsCXXRecordDecl();
3226 
3227  CharUnits VBaseOffset = Offset + Layout.getVBaseClassOffset(VBase);
3228 
3229  if (VtorDisps.find(VBase)->second.hasVtorDisp()) {
3230  PrintOffset(OS, VBaseOffset - CharUnits::fromQuantity(4), IndentLevel);
3231  OS << "(vtordisp for vbase " << *VBase << ")\n";
3232  }
3233 
3234  DumpRecordLayout(OS, VBase, C, VBaseOffset, IndentLevel,
3235  VBase == Layout.getPrimaryBase() ?
3236  "(primary virtual base)" : "(virtual base)",
3237  /*PrintSizeInfo=*/false,
3238  /*IncludeVirtualBases=*/false);
3239  }
3240  }
3241 
3242  if (!PrintSizeInfo) return;
3243 
3244  PrintIndentNoOffset(OS, IndentLevel - 1);
3245  OS << "[sizeof=" << Layout.getSize().getQuantity();
3246  if (CXXRD && !isMsLayout(C))
3247  OS << ", dsize=" << Layout.getDataSize().getQuantity();
3248  OS << ", align=" << Layout.getAlignment().getQuantity();
3249 
3250  if (CXXRD) {
3251  OS << ",\n";
3252  PrintIndentNoOffset(OS, IndentLevel - 1);
3253  OS << " nvsize=" << Layout.getNonVirtualSize().getQuantity();
3254  OS << ", nvalign=" << Layout.getNonVirtualAlignment().getQuantity();
3255  }
3256  OS << "]\n";
3257 }
3258 
3260  raw_ostream &OS,
3261  bool Simple) const {
3262  if (!Simple) {
3263  ::DumpRecordLayout(OS, RD, *this, CharUnits(), 0, nullptr,
3264  /*PrintSizeInfo*/true,
3265  /*IncludeVirtualBases=*/true);
3266  return;
3267  }
3268 
3269  // The "simple" format is designed to be parsed by the
3270  // layout-override testing code. There shouldn't be any external
3271  // uses of this format --- when LLDB overrides a layout, it sets up
3272  // the data structures directly --- so feel free to adjust this as
3273  // you like as long as you also update the rudimentary parser for it
3274  // in libFrontend.
3275 
3276  const ASTRecordLayout &Info = getASTRecordLayout(RD);
3277  OS << "Type: " << getTypeDeclType(RD).getAsString() << "\n";
3278  OS << "\nLayout: ";
3279  OS << "<ASTRecordLayout\n";
3280  OS << " Size:" << toBits(Info.getSize()) << "\n";
3281  if (!isMsLayout(*this))
3282  OS << " DataSize:" << toBits(Info.getDataSize()) << "\n";
3283  OS << " Alignment:" << toBits(Info.getAlignment()) << "\n";
3284  OS << " FieldOffsets: [";
3285  for (unsigned i = 0, e = Info.getFieldCount(); i != e; ++i) {
3286  if (i) OS << ", ";
3287  OS << Info.getFieldOffset(i);
3288  }
3289  OS << "]>\n";
3290 }
static uint64_t getFieldOffset(const ASTContext &C, const FieldDecl *FD)
unsigned getAddressSpace() const
Return the address space of this type.
Definition: Type.h:5204
Defines the clang::ASTContext interface.
FunctionDecl - An instance of this class is created to represent a function declaration or definition...
Definition: Decl.h:1483
Only allocate objects in the tail padding of a base class if the base class is not POD according to t...
Definition: TargetCXXABI.h:310
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.
StringRef getName() const
getName - Get the name of identifier for this declaration as a StringRef.
Definition: Decl.h:169
unsigned getZeroLengthBitfieldBoundary() const
Get the fixed alignment value in bits for a member that follows a zero length bitfield.
A (possibly-)qualified type.
Definition: Type.h:575
llvm::DenseMap< const CXXRecordDecl *, VBaseInfo > VBaseOffsetsMapTy
Definition: RecordLayout.h:57
static bool mustSkipTailPadding(TargetCXXABI ABI, const CXXRecordDecl *RD)
Does the target C++ ABI require us to skip over the tail-padding of the given class (considering it a...
static void DumpRecordLayout(raw_ostream &OS, const RecordDecl *RD, const ASTContext &C, CharUnits Offset, unsigned IndentLevel, const char *Description, bool PrintSizeInfo, bool IncludeVirtualBases)
base_class_range bases()
Definition: DeclCXX.h:713
unsigned getFieldCount() const
getFieldCount - Get the number of fields in the layout.
Definition: RecordLayout.h:177
bool hasZeroSizedSubObject() const
Definition: RecordLayout.h:286
bool isBitField() const
Determines whether this field is a bitfield.
Definition: Decl.h:2277
The basic abstraction for the target C++ ABI.
Definition: TargetCXXABI.h:25
IdentifierInfo * getIdentifier() const
getIdentifier - Get the identifier that names this declaration, if there is one.
Definition: Decl.h:164
method_range methods() const
Definition: DeclCXX.h:755
CharUnits getAlignment() const
getAlignment - Get the record alignment in characters.
Definition: RecordLayout.h:171
bool isThisDeclarationADefinition() const
Determine whether this particular declaration of this class is actually also a definition.
Definition: DeclObjC.h:1197
QuantityType getQuantity() const
getQuantity - Get the raw integer representation of this quantity.
Definition: CharUnits.h:171
Decl - This represents one declaration (or definition), e.g.
Definition: DeclBase.h:77
chain_range chain() const
Definition: Decl.h:2457
bool hasFlexibleArrayMember() const
Definition: Decl.h:3218
bool isAlignmentRequired(const Type *T) const
Determine if the alignment the type has was required using an alignment attribute.
method_iterator method_begin() const
Method begin iterator.
Definition: DeclCXX.h:761
std::string getAsString() const
Definition: Type.h:901
The base class of the type hierarchy.
Definition: Type.h:1249
std::unique_ptr< llvm::MemoryBuffer > Buffer
DiagnosticBuilder Report(SourceLocation Loc, unsigned DiagID)
Issue the message to the client.
Definition: Diagnostic.h:1117
Represents an array type, per C99 6.7.5.2 - Array Declarators.
Definition: Type.h:2424
CharUnits getVBaseClassOffset(const CXXRecordDecl *VBase) const
getVBaseClassOffset - Get the offset, in chars, for the given base class.
Definition: RecordLayout.h:232
bool isPrimaryBaseVirtual() const
isPrimaryBaseVirtual - Get whether the primary base for this record is virtual or not...
Definition: RecordLayout.h:217
field_iterator field_begin() const
Definition: Decl.cpp:3746
The "__interface" keyword.
Definition: Type.h:4178
uint64_t getTypeSize(QualType T) const
Return the size of the specified (complete) type T, in bits.
Definition: ASTContext.h:1793
const Type * getUnqualifiedDesugaredType() const
Return the specified type with any "sugar" removed from the type, removing any typedefs, typeofs, etc., as well as any qualifiers.
Definition: Type.cpp:341
RecordDecl - Represents a struct/union/class.
Definition: Decl.h:3166
unsigned getMaxAlignment() const
getMaxAlignment - return the maximum alignment specified by attributes on this decl, 0 if there are none.
Definition: DeclBase.cpp:319
MSVtorDispAttr::Mode getMSVtorDispMode() const
Controls when vtordisps will be emitted if this record is used as a virtual base. ...
bool isEmpty() const
Determine whether this is an empty class in the sense of (C++11 [meta.unary.prop]).
Definition: DeclCXX.h:1144
method_iterator end_overridden_methods() const
Definition: DeclCXX.cpp:1588
bool hasAttr() const
Definition: DeclBase.h:498
Holds long-lived AST nodes (such as types and decls) that can be referred to throughout the semantic ...
Definition: ASTContext.h:91
bool hasExternalLexicalStorage() const
Whether this DeclContext has external storage containing additional declarations that are lexically i...
Definition: DeclBase.h:1742
FieldDecl - An instance of this class is created by Sema::ActOnField to represent a member of a struc...
Definition: Decl.h:2209
bool isCompleteDefinition() const
isCompleteDefinition - Return true if this decl has its body fully specified.
Definition: Decl.h:2788
static bool RequiresVtordisp(const llvm::SmallPtrSetImpl< const CXXRecordDecl * > &BasesWithOverriddenMethods, const CXXRecordDecl *RD)
CXXRecordDecl * getDefinition() const
Definition: DeclCXX.h:675
TagKind getTagKind() const
Definition: Decl.h:2847
static CharUnits Zero()
Zero - Construct a CharUnits quantity of zero.
Definition: CharUnits.h:53
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:1191
void getIndirectPrimaryBases(CXXIndirectPrimaryBaseSet &Bases) const
Get the indirect primary bases for this class.
bool isNearlyEmpty(const CXXRecordDecl *RD) const
T * getAttr() const
Definition: DeclBase.h:495
unsigned CountNonClassIvars(const ObjCInterfaceDecl *OI) const
const TargetInfo & getTargetInfo() const
Definition: ASTContext.h:580
ObjCContainerDecl - Represents a container for method declarations.
Definition: DeclObjC.h:696
const LangOptions & getLangOpts() const
Definition: ASTContext.h:596
CharUnits - This is an opaque type for sizes expressed in character units.
Definition: CharUnits.h:38
uint32_t Offset
Definition: CacheTokens.cpp:44
const CXXRecordDecl * getParent() const
Returns the parent of this method declaration, which is the class in which this method is defined...
Definition: DeclCXX.h:1801
field_range fields() const
Definition: Decl.h:3295
CharUnits getRequiredAlignment() const
Definition: RecordLayout.h:282
bool hasVBPtr() const
hasVBPtr - Does this class have a virtual function table pointer.
Definition: RecordLayout.h:277
const ArrayType * getAsArrayType(QualType T) const
Type Query functions.
RecordDecl * getDecl() const
Definition: Type.h:3553
unsigned Align
Definition: ASTContext.h:82
const ASTRecordLayout & getASTRecordLayout(const RecordDecl *D) const
Get or compute information about the layout of the specified record (struct/union/class) D...
uint64_t getFieldOffset(unsigned FieldNo) const
getFieldOffset - Get the offset of the given field index, in bits.
Definition: RecordLayout.h:181
CharUnits getTypeSizeInChars(QualType T) const
Return the size of the specified (complete) type T, in characters.
Represents an ObjC class declaration.
Definition: DeclObjC.h:853
detail::InMemoryDirectory::const_iterator I
std::pair< CharUnits, CharUnits > getTypeInfoInChars(const Type *T) const
CanQualType UnsignedCharTy
Definition: ASTContext.h:890
QualType getType() const
Definition: Decl.h:530
bool isInvalid() const
DiagnosticsEngine & getDiagnostics() const
field_iterator field_end() const
Definition: Decl.h:3298
bool isUnion() const
Definition: Decl.h:2856
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:866
static void PrintOffset(raw_ostream &OS, CharUnits Offset, unsigned IndentLevel)
ASTContext * Context
const SmallVectorImpl< AnnotatedLine * >::const_iterator End
const CXXMethodDecl *const * method_iterator
Definition: DeclCXX.h:1793
QualType getPointeeType() const
If this is a pointer, ObjC object pointer, or block pointer, this returns the respective pointee...
Definition: Type.cpp:415
bool hasOwnVBPtr() const
hasOwnVBPtr - Does this class provide its own virtual-base table pointer, rather than inheriting one ...
Definition: RecordLayout.h:271
ASTRecordLayout - This class contains layout information for one RecordDecl, which is a struct/union/...
Definition: RecordLayout.h:34
bool canKeyFunctionBeInline() const
Can an out-of-line inline function serve as a key function?
Definition: TargetCXXABI.h:267
bool isMicrosoft() const
Is this ABI an MSVC-compatible ABI?
Definition: TargetCXXABI.h:155
ValueDecl - Represent the declaration of a variable (in which case it is an lvalue) a function (in wh...
Definition: Decl.h:521
#define bool
Definition: stdbool.h:31
bool leadsWithZeroSizedBase() const
Definition: RecordLayout.h:290
CharUnits getNonVirtualAlignment() const
getNonVirtualSize - Get the non-virtual alignment (in chars) of an object, which is the alignment of ...
Definition: RecordLayout.h:202
CharUnits getBaseClassOffset(const CXXRecordDecl *Base) const
getBaseClassOffset - Get the offset, in chars, for the given base class.
Definition: RecordLayout.h:224
static CharUnits fromQuantity(QuantityType Quantity)
fromQuantity - Construct a CharUnits quantity from a raw integer type.
Definition: CharUnits.h:63
bool useZeroLengthBitfieldAlignment() const
Check whether zero length bitfields should force alignment of the next member.
TailPaddingUseRules getTailPaddingUseRules() const
Definition: TargetCXXABI.h:316
CharUnits toCharUnitsFromBits(int64_t BitSize) const
Convert a size in bits to a size in characters.
bool isExternallyVisible() const
Definition: Decl.h:280
CharUnits getVBPtrOffset() const
getVBPtrOffset - Get the offset for virtual base table pointer.
Definition: RecordLayout.h:297
bool useBitFieldTypeAlignment() const
Check whether the alignment of bit-field types is respected when laying out structures.
specific_decl_iterator< FieldDecl > field_iterator
Definition: Decl.h:3292
CharUnits getSizeOfLargestEmptySubobject() const
Definition: RecordLayout.h:239
The result type of a method or function.
This template specialization was implicitly instantiated from a template.
Definition: Specifiers.h:144
RecordDecl * getDefinition() const
getDefinition - Returns the RecordDecl that actually defines this struct/union/class.
Definition: Decl.h:3285
decl_type * getFirstDecl()
Return the first declaration of this declaration or itself if this is the only declaration.
Definition: Redeclarable.h:156
uint64_t getFieldOffset(const ValueDecl *FD) const
Get the offset of a FieldDecl or IndirectFieldDecl, in bits.
Abstract interface for external sources of AST nodes.
static uint64_t roundUpSizeToCharAlignment(uint64_t Size, const ASTContext &Context)
TypeInfo getTypeInfo(const Type *T) const
Get the size and alignment of the specified complete type in bits.
#define false
Definition: stdbool.h:33
CharUnits getTypeAlignInChars(QualType T) const
Return the ABI-specified alignment of a (complete) type T, in characters.
The "struct" keyword.
Definition: Type.h:4176
uint64_t getPointerAlign(unsigned AddrSpace) const
bool mayInsertExtraPadding(bool EmitRemark=false) const
Whether we are allowed to insert extra padding between fields.
Definition: Decl.cpp:3793
SmallVectorImpl< AnnotatedLine * >::const_iterator Next
Only allocate objects in the tail padding of a base class if the base class is not POD according to t...
Definition: TargetCXXABI.h:314
Encodes a location in the source.
ExternalASTSource * getExternalSource() const
Retrieve a pointer to the external AST source associated with this AST context, if any...
Definition: ASTContext.h:932
const TemplateArgument * iterator
Definition: Type.h:4070
CharUnits getSize() const
getSize - Get the record size in characters.
Definition: RecordLayout.h:174
method_iterator begin_overridden_methods() const
Definition: DeclCXX.cpp:1583
unsigned getBitWidthValue(const ASTContext &Ctx) const
Definition: Decl.cpp:3463
const CXXRecordDecl * getPrimaryBase() const
getPrimaryBase - Get the primary base for this record.
Definition: RecordLayout.h:209
A set of all the primary bases for a class.
static void PrintIndentNoOffset(raw_ostream &OS, unsigned IndentLevel)
Represents a static or instance method of a struct/union/class.
Definition: DeclCXX.h:1701
bool hasExtendableVFPtr() const
hasVFPtr - Does this class have a virtual function table pointer that can be extended by a derived cl...
Definition: RecordLayout.h:259
const ConstantArrayType * getAsConstantArrayType(QualType T) const
Definition: ASTContext.h:2094
const VBaseOffsetsMapTy & getVBaseOffsetsMap() const
Definition: RecordLayout.h:307
const Type * getBaseElementTypeUnsafe() const
Get the base element type of this type, potentially discarding type qualifiers.
Definition: Type.h:5640
T * get(ExternalASTSource *Source) const
Retrieve the pointer to the AST node that this lazy pointer.
lookup_result lookup(DeclarationName Name) const
lookup - Find the declarations (if any) with the given Name in this context.
Definition: DeclBase.cpp:1368
This template specialization was instantiated from a template due to an explicit instantiation defini...
Definition: Specifiers.h:156
method_iterator method_end() const
Method past-the-end iterator.
Definition: DeclCXX.h:765
bool isInlineSpecified() const
Determine whether the "inline" keyword was specified for this function.
Definition: Decl.h:1983
static unsigned getPaddingDiagFromTagKind(TagTypeKind Tag)
Get diagnostic select index for tag kind for field padding diagnostic message.
bool isDynamicClass() const
Definition: DeclCXX.h:693
CanQualType UnsignedShortTy
Definition: ASTContext.h:890
ObjCIvarDecl * getNextIvar()
Definition: DeclObjC.h:1642
if(T->getSizeExpr()) TRY_TO(TraverseStmt(T-> getSizeExpr()))
TemplateSpecializationKind getTemplateSpecializationKind() const
Determine whether this particular class is a specialization or instantiation of a class template or m...
Definition: DeclCXX.cpp:1243
TagTypeKind
The kind of a tag type.
Definition: Type.h:4174
return(x >> y)|(x<< (32-y))
bool isInvalidDecl() const
Definition: DeclBase.h:509
IndirectFieldDecl - An instance of this class is created to represent a field injected from an anonym...
Definition: Decl.h:2437
CanQualType UnsignedLongLongTy
Definition: ASTContext.h:891
ObjCInterfaceDecl * getDefinition()
Retrieve the definition of this class, or NULL if this class has been forward-declared (with @class) ...
Definition: DeclObjC.h:1216
This template specialization was instantiated from a template due to an explicit instantiation declar...
Definition: Specifiers.h:152
const llvm::Triple & getTriple() const
Returns the target triple of the primary target.
detail::InMemoryDirectory::const_iterator E
TemplateSpecializationKind
Describes the kind of template specialization that a particular template specialization declaration r...
Definition: Specifiers.h:138
bool isMsStruct(const ASTContext &C) const
isMsStrust - Get whether or not this is an ms_struct which can be turned on with an attribute...
Definition: Decl.cpp:3763
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:1459
unsigned Map[Count]
The type of a lookup table which maps from language-specific address spaces to target-specific ones...
Definition: AddressSpaces.h:45
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:2220
A helper class that allows the use of isa/cast/dyncast to detect TagType objects of structs/unions/cl...
Definition: Type.h:3544
const T * getAs() const
Member-template getAs<specific type>'.
Definition: Type.h:5675
CanQualType UnsignedLongTy
Definition: ASTContext.h:890
void setNonKeyFunction(const CXXMethodDecl *method)
Observe that the given method cannot be a key function.
virtual void CompleteType(TagDecl *Tag)
Gives the external AST source an opportunity to complete an incomplete type.
Base for LValueReferenceType and RValueReferenceType.
Definition: Type.h:2287
CXXRecordDecl * getAsCXXRecordDecl() const
Retrieves the CXXRecordDecl that this type refers to, either because the type is a RecordType or beca...
Definition: Type.cpp:1522
bool isTrivial() const
Determine whether this class is considered trivial.
Definition: DeclCXX.h:1297
uint64_t getCharWidth() const
Return the size of the character type, in bits.
Definition: ASTContext.h:1797
The "class" keyword.
Definition: Type.h:4182
Represents a base class of a C++ class.
Definition: DeclCXX.h:157
CharUnits getNonVirtualSize() const
getNonVirtualSize - Get the non-virtual size (in chars) of an object, which is the size of the object...
Definition: RecordLayout.h:194
unsigned getFieldIndex() const
getFieldIndex - Returns the index of this field within its record, as appropriate for passing to ASTR...
Definition: Decl.cpp:3469
uint64_t getPointerWidth(unsigned AddrSpace) const
Return the width of pointers on this target, for the specified address space.
Defines the C++ Decl subclasses, other than those for templates (found in DeclTemplate.h) and friends (in DeclFriend.h).
const CXXMethodDecl * getCurrentKeyFunction(const CXXRecordDecl *RD)
Get our current best idea for the key function of the given record decl, or NULL if there isn't one...
Represents a C++ struct/union/class.
Definition: DeclCXX.h:285
BoundNodesTreeBuilder *const Builder
TargetCXXABI getCXXABI() const
Get the C++ ABI currently in use.
bool hasUserDeclaredDestructor() const
Determine whether this class has a user-declared destructor.
Definition: DeclCXX.h:1005
ObjCIvarDecl - Represents an ObjC instance variable.
Definition: DeclObjC.h:1609
void DumpRecordLayout(const RecordDecl *RD, raw_ostream &OS, bool Simple=false) const
CharUnits getDataSize() const
getDataSize() - Get the record data size, which is the record size without tail padding, in characters.
Definition: RecordLayout.h:188
static bool isMsLayout(const ASTContext &Context)
This class is used for builtin types like 'int'.
Definition: Type.h:2011
static const CXXMethodDecl * computeKeyFunction(ASTContext &Context, const CXXRecordDecl *RD)
The tail-padding of a base class is always theoretically available, even if it's POD.
Definition: TargetCXXABI.h:305
Defines the clang::TargetInfo interface.
ObjCInterfaceDecl * getSuperClass() const
Definition: DeclObjC.cpp:289
bool hasOwnVFPtr() const
hasOwnVFPtr - Does this class provide its own virtual-function table pointer, rather than inheriting ...
Definition: RecordLayout.h:251
static void PrintBitFieldOffset(raw_ostream &OS, CharUnits Offset, unsigned Begin, unsigned Width, unsigned IndentLevel)
uint64_t Width
Definition: ASTContext.h:81
bool isIncompleteArrayType() const
Definition: Type.h:5350
bool isStandardLayout() const
Determine whether this class has standard layout per (C++ [class]p7)
Definition: DeclCXX.h:1159
QualType getElementType() const
Definition: Type.h:2458
uint64_t getConstantArrayElementCount(const ConstantArrayType *CA) const
Return number of constant array elements.
int64_t toBits(CharUnits CharSize) const
Convert a size in characters to a size in bits.
SourceLocation getLocation() const
Definition: DeclBase.h:384
unsigned getNumVBases() const
Retrieves the number of virtual base classes of this class.
Definition: DeclCXX.h:728
NamedDecl - This represents a decl with a name.
Definition: Decl.h:145
ObjCIvarDecl * all_declared_ivar_begin()
all_declared_ivar_begin - return first ivar declared in this class, its extensions and its implementa...
Definition: DeclObjC.cpp:1487
const ASTRecordLayout & getASTObjCInterfaceLayout(const ObjCInterfaceDecl *D) const
Get or compute information about the layout of the specified Objective-C interface.
bool isNull() const
Return true if this QualType doesn't point to a type yet.
Definition: Type.h:642
bool isPolymorphic() const
Whether this class is polymorphic (C++ [class.virtual]), which means that the class contains or inher...
Definition: DeclCXX.h:1148
CharUnits RoundUpToAlignment(const CharUnits &Align) const
RoundUpToAlignment - Returns the next integer (mod 2**64) that is greater than or equal to this quant...
Definition: CharUnits.h:176
Represents the canonical version of C arrays with a specified constant size.
Definition: Type.h:2480
base_class_range vbases()
Definition: DeclCXX.h:730
QualType getBaseElementType(const ArrayType *VAT) const
Return the innermost element type of an array type.
bool hasUserDeclaredConstructor() const
Determine whether this class has any user-declared constructors.
Definition: DeclCXX.h:839
const RecordDecl * getParent() const
getParent - Returns the parent of this field declaration, which is the struct in which this method is...
Definition: Decl.h:2371
CanQualType UnsignedIntTy
Definition: ASTContext.h:890
bool isPOD() const
Whether this class is a POD-type (C++ [class]p4)
Definition: DeclCXX.h:1130