clang  9.0.0svn
RecordLayoutBuilder.cpp
Go to the documentation of this file.
1 //=== RecordLayoutBuilder.cpp - Helper class for building record layouts ---==//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
10 #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"
19 #include "llvm/ADT/SmallSet.h"
20 #include "llvm/Support/Format.h"
21 #include "llvm/Support/MathExtras.h"
22 
23 using namespace clang;
24 
25 namespace {
26 
27 /// BaseSubobjectInfo - Represents a single base subobject in a complete class.
28 /// For a class hierarchy like
29 ///
30 /// class A { };
31 /// class B : A { };
32 /// class C : A, B { };
33 ///
34 /// The BaseSubobjectInfo graph for C will have three BaseSubobjectInfo
35 /// instances, one for B and two for A.
36 ///
37 /// If a base is virtual, it will only have one BaseSubobjectInfo allocated.
38 struct BaseSubobjectInfo {
39  /// Class - The class for this base info.
40  const CXXRecordDecl *Class;
41 
42  /// IsVirtual - Whether the BaseInfo represents a virtual base or not.
43  bool IsVirtual;
44 
45  /// Bases - Information about the base subobjects.
47 
48  /// PrimaryVirtualBaseInfo - Holds the base info for the primary virtual base
49  /// of this base info (if one exists).
50  BaseSubobjectInfo *PrimaryVirtualBaseInfo;
51 
52  // FIXME: Document.
53  const BaseSubobjectInfo *Derived;
54 };
55 
56 /// Externally provided layout. Typically used when the AST source, such
57 /// as DWARF, lacks all the information that was available at compile time, such
58 /// as alignment attributes on fields and pragmas in effect.
59 struct ExternalLayout {
60  ExternalLayout() : Size(0), Align(0) {}
61 
62  /// Overall record size in bits.
63  uint64_t Size;
64 
65  /// Overall record alignment in bits.
66  uint64_t Align;
67 
68  /// Record field offsets in bits.
69  llvm::DenseMap<const FieldDecl *, uint64_t> FieldOffsets;
70 
71  /// Direct, non-virtual base offsets.
72  llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsets;
73 
74  /// Virtual base offsets.
75  llvm::DenseMap<const CXXRecordDecl *, CharUnits> VirtualBaseOffsets;
76 
77  /// Get the offset of the given field. The external source must provide
78  /// entries for all fields in the record.
79  uint64_t getExternalFieldOffset(const FieldDecl *FD) {
80  assert(FieldOffsets.count(FD) &&
81  "Field does not have an external offset");
82  return FieldOffsets[FD];
83  }
84 
85  bool getExternalNVBaseOffset(const CXXRecordDecl *RD, CharUnits &BaseOffset) {
86  auto Known = BaseOffsets.find(RD);
87  if (Known == BaseOffsets.end())
88  return false;
89  BaseOffset = Known->second;
90  return true;
91  }
92 
93  bool getExternalVBaseOffset(const CXXRecordDecl *RD, CharUnits &BaseOffset) {
94  auto Known = VirtualBaseOffsets.find(RD);
95  if (Known == VirtualBaseOffsets.end())
96  return false;
97  BaseOffset = Known->second;
98  return true;
99  }
100 };
101 
102 /// EmptySubobjectMap - Keeps track of which empty subobjects exist at different
103 /// offsets while laying out a C++ class.
104 class EmptySubobjectMap {
105  const ASTContext &Context;
106  uint64_t CharWidth;
107 
108  /// Class - The class whose empty entries we're keeping track of.
109  const CXXRecordDecl *Class;
110 
111  /// EmptyClassOffsets - A map from offsets to empty record decls.
112  typedef llvm::TinyPtrVector<const CXXRecordDecl *> ClassVectorTy;
113  typedef llvm::DenseMap<CharUnits, ClassVectorTy> EmptyClassOffsetsMapTy;
114  EmptyClassOffsetsMapTy EmptyClassOffsets;
115 
116  /// MaxEmptyClassOffset - The highest offset known to contain an empty
117  /// base subobject.
118  CharUnits MaxEmptyClassOffset;
119 
120  /// ComputeEmptySubobjectSizes - Compute the size of the largest base or
121  /// member subobject that is empty.
122  void ComputeEmptySubobjectSizes();
123 
124  void AddSubobjectAtOffset(const CXXRecordDecl *RD, CharUnits Offset);
125 
126  void UpdateEmptyBaseSubobjects(const BaseSubobjectInfo *Info,
127  CharUnits Offset, bool PlacingEmptyBase);
128 
129  void UpdateEmptyFieldSubobjects(const CXXRecordDecl *RD,
130  const CXXRecordDecl *Class,
131  CharUnits Offset);
132  void UpdateEmptyFieldSubobjects(const FieldDecl *FD, CharUnits Offset);
133 
134  /// AnyEmptySubobjectsBeyondOffset - Returns whether there are any empty
135  /// subobjects beyond the given offset.
136  bool AnyEmptySubobjectsBeyondOffset(CharUnits Offset) const {
137  return Offset <= MaxEmptyClassOffset;
138  }
139 
140  CharUnits
141  getFieldOffset(const ASTRecordLayout &Layout, unsigned FieldNo) const {
142  uint64_t FieldOffset = Layout.getFieldOffset(FieldNo);
143  assert(FieldOffset % CharWidth == 0 &&
144  "Field offset not at char boundary!");
145 
146  return Context.toCharUnitsFromBits(FieldOffset);
147  }
148 
149 protected:
150  bool CanPlaceSubobjectAtOffset(const CXXRecordDecl *RD,
151  CharUnits Offset) const;
152 
153  bool CanPlaceBaseSubobjectAtOffset(const BaseSubobjectInfo *Info,
154  CharUnits Offset);
155 
156  bool CanPlaceFieldSubobjectAtOffset(const CXXRecordDecl *RD,
157  const CXXRecordDecl *Class,
158  CharUnits Offset) const;
159  bool CanPlaceFieldSubobjectAtOffset(const FieldDecl *FD,
160  CharUnits Offset) const;
161 
162 public:
163  /// This holds the size of the largest empty subobject (either a base
164  /// or a member). Will be zero if the record being built doesn't contain
165  /// any empty classes.
166  CharUnits SizeOfLargestEmptySubobject;
167 
168  EmptySubobjectMap(const ASTContext &Context, const CXXRecordDecl *Class)
169  : Context(Context), CharWidth(Context.getCharWidth()), Class(Class) {
170  ComputeEmptySubobjectSizes();
171  }
172 
173  /// CanPlaceBaseAtOffset - Return whether the given base class can be placed
174  /// at the given offset.
175  /// Returns false if placing the record will result in two components
176  /// (direct or indirect) of the same type having the same offset.
177  bool CanPlaceBaseAtOffset(const BaseSubobjectInfo *Info,
178  CharUnits Offset);
179 
180  /// CanPlaceFieldAtOffset - Return whether a field can be placed at the given
181  /// offset.
182  bool CanPlaceFieldAtOffset(const FieldDecl *FD, CharUnits Offset);
183 };
184 
185 void EmptySubobjectMap::ComputeEmptySubobjectSizes() {
186  // Check the bases.
187  for (const CXXBaseSpecifier &Base : Class->bases()) {
188  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
189 
190  CharUnits EmptySize;
191  const ASTRecordLayout &Layout = Context.getASTRecordLayout(BaseDecl);
192  if (BaseDecl->isEmpty()) {
193  // If the class decl is empty, get its size.
194  EmptySize = Layout.getSize();
195  } else {
196  // Otherwise, we get the largest empty subobject for the decl.
197  EmptySize = Layout.getSizeOfLargestEmptySubobject();
198  }
199 
200  if (EmptySize > SizeOfLargestEmptySubobject)
201  SizeOfLargestEmptySubobject = EmptySize;
202  }
203 
204  // Check the fields.
205  for (const FieldDecl *FD : Class->fields()) {
206  const RecordType *RT =
207  Context.getBaseElementType(FD->getType())->getAs<RecordType>();
208 
209  // We only care about record types.
210  if (!RT)
211  continue;
212 
213  CharUnits EmptySize;
214  const CXXRecordDecl *MemberDecl = RT->getAsCXXRecordDecl();
215  const ASTRecordLayout &Layout = Context.getASTRecordLayout(MemberDecl);
216  if (MemberDecl->isEmpty()) {
217  // If the class decl is empty, get its size.
218  EmptySize = Layout.getSize();
219  } else {
220  // Otherwise, we get the largest empty subobject for the decl.
221  EmptySize = Layout.getSizeOfLargestEmptySubobject();
222  }
223 
224  if (EmptySize > SizeOfLargestEmptySubobject)
225  SizeOfLargestEmptySubobject = EmptySize;
226  }
227 }
228 
229 bool
230 EmptySubobjectMap::CanPlaceSubobjectAtOffset(const CXXRecordDecl *RD,
231  CharUnits Offset) const {
232  // We only need to check empty bases.
233  if (!RD->isEmpty())
234  return true;
235 
236  EmptyClassOffsetsMapTy::const_iterator I = EmptyClassOffsets.find(Offset);
237  if (I == EmptyClassOffsets.end())
238  return true;
239 
240  const ClassVectorTy &Classes = I->second;
241  if (std::find(Classes.begin(), Classes.end(), RD) == Classes.end())
242  return true;
243 
244  // There is already an empty class of the same type at this offset.
245  return false;
246 }
247 
248 void EmptySubobjectMap::AddSubobjectAtOffset(const CXXRecordDecl *RD,
249  CharUnits Offset) {
250  // We only care about empty bases.
251  if (!RD->isEmpty())
252  return;
253 
254  // If we have empty structures inside a union, we can assign both
255  // the same offset. Just avoid pushing them twice in the list.
256  ClassVectorTy &Classes = EmptyClassOffsets[Offset];
257  if (llvm::is_contained(Classes, RD))
258  return;
259 
260  Classes.push_back(RD);
261 
262  // Update the empty class offset.
263  if (Offset > MaxEmptyClassOffset)
264  MaxEmptyClassOffset = Offset;
265 }
266 
267 bool
268 EmptySubobjectMap::CanPlaceBaseSubobjectAtOffset(const BaseSubobjectInfo *Info,
269  CharUnits Offset) {
270  // We don't have to keep looking past the maximum offset that's known to
271  // contain an empty class.
272  if (!AnyEmptySubobjectsBeyondOffset(Offset))
273  return true;
274 
275  if (!CanPlaceSubobjectAtOffset(Info->Class, Offset))
276  return false;
277 
278  // Traverse all non-virtual bases.
279  const ASTRecordLayout &Layout = Context.getASTRecordLayout(Info->Class);
280  for (const BaseSubobjectInfo *Base : Info->Bases) {
281  if (Base->IsVirtual)
282  continue;
283 
284  CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base->Class);
285 
286  if (!CanPlaceBaseSubobjectAtOffset(Base, BaseOffset))
287  return false;
288  }
289 
290  if (Info->PrimaryVirtualBaseInfo) {
291  BaseSubobjectInfo *PrimaryVirtualBaseInfo = Info->PrimaryVirtualBaseInfo;
292 
293  if (Info == PrimaryVirtualBaseInfo->Derived) {
294  if (!CanPlaceBaseSubobjectAtOffset(PrimaryVirtualBaseInfo, Offset))
295  return false;
296  }
297  }
298 
299  // Traverse all member variables.
300  unsigned FieldNo = 0;
301  for (CXXRecordDecl::field_iterator I = Info->Class->field_begin(),
302  E = Info->Class->field_end(); I != E; ++I, ++FieldNo) {
303  if (I->isBitField())
304  continue;
305 
306  CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
307  if (!CanPlaceFieldSubobjectAtOffset(*I, FieldOffset))
308  return false;
309  }
310 
311  return true;
312 }
313 
314 void EmptySubobjectMap::UpdateEmptyBaseSubobjects(const BaseSubobjectInfo *Info,
315  CharUnits Offset,
316  bool PlacingEmptyBase) {
317  if (!PlacingEmptyBase && Offset >= SizeOfLargestEmptySubobject) {
318  // We know that the only empty subobjects that can conflict with empty
319  // subobject of non-empty bases, are empty bases that can be placed at
320  // offset zero. Because of this, we only need to keep track of empty base
321  // subobjects with offsets less than the size of the largest empty
322  // subobject for our class.
323  return;
324  }
325 
326  AddSubobjectAtOffset(Info->Class, Offset);
327 
328  // Traverse all non-virtual bases.
329  const ASTRecordLayout &Layout = Context.getASTRecordLayout(Info->Class);
330  for (const BaseSubobjectInfo *Base : Info->Bases) {
331  if (Base->IsVirtual)
332  continue;
333 
334  CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base->Class);
335  UpdateEmptyBaseSubobjects(Base, BaseOffset, PlacingEmptyBase);
336  }
337 
338  if (Info->PrimaryVirtualBaseInfo) {
339  BaseSubobjectInfo *PrimaryVirtualBaseInfo = Info->PrimaryVirtualBaseInfo;
340 
341  if (Info == PrimaryVirtualBaseInfo->Derived)
342  UpdateEmptyBaseSubobjects(PrimaryVirtualBaseInfo, Offset,
343  PlacingEmptyBase);
344  }
345 
346  // Traverse all member variables.
347  unsigned FieldNo = 0;
348  for (CXXRecordDecl::field_iterator I = Info->Class->field_begin(),
349  E = Info->Class->field_end(); I != E; ++I, ++FieldNo) {
350  if (I->isBitField())
351  continue;
352 
353  CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
354  UpdateEmptyFieldSubobjects(*I, FieldOffset);
355  }
356 }
357 
358 bool EmptySubobjectMap::CanPlaceBaseAtOffset(const BaseSubobjectInfo *Info,
359  CharUnits Offset) {
360  // If we know this class doesn't have any empty subobjects we don't need to
361  // bother checking.
362  if (SizeOfLargestEmptySubobject.isZero())
363  return true;
364 
365  if (!CanPlaceBaseSubobjectAtOffset(Info, Offset))
366  return false;
367 
368  // We are able to place the base at this offset. Make sure to update the
369  // empty base subobject map.
370  UpdateEmptyBaseSubobjects(Info, Offset, Info->Class->isEmpty());
371  return true;
372 }
373 
374 bool
375 EmptySubobjectMap::CanPlaceFieldSubobjectAtOffset(const CXXRecordDecl *RD,
376  const CXXRecordDecl *Class,
377  CharUnits Offset) const {
378  // We don't have to keep looking past the maximum offset that's known to
379  // contain an empty class.
380  if (!AnyEmptySubobjectsBeyondOffset(Offset))
381  return true;
382 
383  if (!CanPlaceSubobjectAtOffset(RD, Offset))
384  return false;
385 
386  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
387 
388  // Traverse all non-virtual bases.
389  for (const CXXBaseSpecifier &Base : RD->bases()) {
390  if (Base.isVirtual())
391  continue;
392 
393  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
394 
395  CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(BaseDecl);
396  if (!CanPlaceFieldSubobjectAtOffset(BaseDecl, Class, BaseOffset))
397  return false;
398  }
399 
400  if (RD == Class) {
401  // This is the most derived class, traverse virtual bases as well.
402  for (const CXXBaseSpecifier &Base : RD->vbases()) {
403  const CXXRecordDecl *VBaseDecl = Base.getType()->getAsCXXRecordDecl();
404 
405  CharUnits VBaseOffset = Offset + Layout.getVBaseClassOffset(VBaseDecl);
406  if (!CanPlaceFieldSubobjectAtOffset(VBaseDecl, Class, VBaseOffset))
407  return false;
408  }
409  }
410 
411  // Traverse all member variables.
412  unsigned FieldNo = 0;
413  for (CXXRecordDecl::field_iterator I = RD->field_begin(), E = RD->field_end();
414  I != E; ++I, ++FieldNo) {
415  if (I->isBitField())
416  continue;
417 
418  CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
419 
420  if (!CanPlaceFieldSubobjectAtOffset(*I, FieldOffset))
421  return false;
422  }
423 
424  return true;
425 }
426 
427 bool
428 EmptySubobjectMap::CanPlaceFieldSubobjectAtOffset(const FieldDecl *FD,
429  CharUnits Offset) const {
430  // We don't have to keep looking past the maximum offset that's known to
431  // contain an empty class.
432  if (!AnyEmptySubobjectsBeyondOffset(Offset))
433  return true;
434 
435  QualType T = FD->getType();
436  if (const CXXRecordDecl *RD = T->getAsCXXRecordDecl())
437  return CanPlaceFieldSubobjectAtOffset(RD, RD, Offset);
438 
439  // If we have an array type we need to look at every element.
440  if (const ConstantArrayType *AT = Context.getAsConstantArrayType(T)) {
441  QualType ElemTy = Context.getBaseElementType(AT);
442  const RecordType *RT = ElemTy->getAs<RecordType>();
443  if (!RT)
444  return true;
445 
446  const CXXRecordDecl *RD = RT->getAsCXXRecordDecl();
447  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
448 
449  uint64_t NumElements = Context.getConstantArrayElementCount(AT);
450  CharUnits ElementOffset = Offset;
451  for (uint64_t I = 0; I != NumElements; ++I) {
452  // We don't have to keep looking past the maximum offset that's known to
453  // contain an empty class.
454  if (!AnyEmptySubobjectsBeyondOffset(ElementOffset))
455  return true;
456 
457  if (!CanPlaceFieldSubobjectAtOffset(RD, RD, ElementOffset))
458  return false;
459 
460  ElementOffset += Layout.getSize();
461  }
462  }
463 
464  return true;
465 }
466 
467 bool
468 EmptySubobjectMap::CanPlaceFieldAtOffset(const FieldDecl *FD,
469  CharUnits Offset) {
470  if (!CanPlaceFieldSubobjectAtOffset(FD, Offset))
471  return false;
472 
473  // We are able to place the member variable at this offset.
474  // Make sure to update the empty base subobject map.
475  UpdateEmptyFieldSubobjects(FD, Offset);
476  return true;
477 }
478 
479 void EmptySubobjectMap::UpdateEmptyFieldSubobjects(const CXXRecordDecl *RD,
480  const CXXRecordDecl *Class,
481  CharUnits Offset) {
482  // We know that the only empty subobjects that can conflict with empty
483  // field subobjects are subobjects of empty bases that can be placed at offset
484  // zero. Because of this, we only need to keep track of empty field
485  // subobjects with offsets less than the size of the largest empty
486  // subobject for our class.
487  if (Offset >= SizeOfLargestEmptySubobject)
488  return;
489 
490  AddSubobjectAtOffset(RD, Offset);
491 
492  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
493 
494  // Traverse all non-virtual bases.
495  for (const CXXBaseSpecifier &Base : RD->bases()) {
496  if (Base.isVirtual())
497  continue;
498 
499  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
500 
501  CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(BaseDecl);
502  UpdateEmptyFieldSubobjects(BaseDecl, Class, BaseOffset);
503  }
504 
505  if (RD == Class) {
506  // This is the most derived class, traverse virtual bases as well.
507  for (const CXXBaseSpecifier &Base : RD->vbases()) {
508  const CXXRecordDecl *VBaseDecl = Base.getType()->getAsCXXRecordDecl();
509 
510  CharUnits VBaseOffset = Offset + Layout.getVBaseClassOffset(VBaseDecl);
511  UpdateEmptyFieldSubobjects(VBaseDecl, Class, VBaseOffset);
512  }
513  }
514 
515  // Traverse all member variables.
516  unsigned FieldNo = 0;
517  for (CXXRecordDecl::field_iterator I = RD->field_begin(), E = RD->field_end();
518  I != E; ++I, ++FieldNo) {
519  if (I->isBitField())
520  continue;
521 
522  CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
523 
524  UpdateEmptyFieldSubobjects(*I, FieldOffset);
525  }
526 }
527 
528 void EmptySubobjectMap::UpdateEmptyFieldSubobjects(const FieldDecl *FD,
529  CharUnits Offset) {
530  QualType T = FD->getType();
531  if (const CXXRecordDecl *RD = T->getAsCXXRecordDecl()) {
532  UpdateEmptyFieldSubobjects(RD, RD, Offset);
533  return;
534  }
535 
536  // If we have an array type we need to update every element.
537  if (const ConstantArrayType *AT = Context.getAsConstantArrayType(T)) {
538  QualType ElemTy = Context.getBaseElementType(AT);
539  const RecordType *RT = ElemTy->getAs<RecordType>();
540  if (!RT)
541  return;
542 
543  const CXXRecordDecl *RD = RT->getAsCXXRecordDecl();
544  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
545 
546  uint64_t NumElements = Context.getConstantArrayElementCount(AT);
547  CharUnits ElementOffset = Offset;
548 
549  for (uint64_t I = 0; I != NumElements; ++I) {
550  // We know that the only empty subobjects that can conflict with empty
551  // field subobjects are subobjects of empty bases that can be placed at
552  // offset zero. Because of this, we only need to keep track of empty field
553  // subobjects with offsets less than the size of the largest empty
554  // subobject for our class.
555  if (ElementOffset >= SizeOfLargestEmptySubobject)
556  return;
557 
558  UpdateEmptyFieldSubobjects(RD, RD, ElementOffset);
559  ElementOffset += Layout.getSize();
560  }
561  }
562 }
563 
564 typedef llvm::SmallPtrSet<const CXXRecordDecl*, 4> ClassSetTy;
565 
566 class ItaniumRecordLayoutBuilder {
567 protected:
568  // FIXME: Remove this and make the appropriate fields public.
569  friend class clang::ASTContext;
570 
571  const ASTContext &Context;
572 
573  EmptySubobjectMap *EmptySubobjects;
574 
575  /// Size - The current size of the record layout.
576  uint64_t Size;
577 
578  /// Alignment - The current alignment of the record layout.
579  CharUnits Alignment;
580 
581  /// The alignment if attribute packed is not used.
582  CharUnits UnpackedAlignment;
583 
584  /// \brief The maximum of the alignments of top-level members.
585  CharUnits UnadjustedAlignment;
586 
587  SmallVector<uint64_t, 16> FieldOffsets;
588 
589  /// Whether the external AST source has provided a layout for this
590  /// record.
591  unsigned UseExternalLayout : 1;
592 
593  /// Whether we need to infer alignment, even when we have an
594  /// externally-provided layout.
595  unsigned InferAlignment : 1;
596 
597  /// Packed - Whether the record is packed or not.
598  unsigned Packed : 1;
599 
600  unsigned IsUnion : 1;
601 
602  unsigned IsMac68kAlign : 1;
603 
604  unsigned IsMsStruct : 1;
605 
606  /// UnfilledBitsInLastUnit - If the last field laid out was a bitfield,
607  /// this contains the number of bits in the last unit that can be used for
608  /// an adjacent bitfield if necessary. The unit in question is usually
609  /// a byte, but larger units are used if IsMsStruct.
610  unsigned char UnfilledBitsInLastUnit;
611  /// LastBitfieldTypeSize - If IsMsStruct, represents the size of the type
612  /// of the previous field if it was a bitfield.
613  unsigned char LastBitfieldTypeSize;
614 
615  /// MaxFieldAlignment - The maximum allowed field alignment. This is set by
616  /// #pragma pack.
617  CharUnits MaxFieldAlignment;
618 
619  /// DataSize - The data size of the record being laid out.
620  uint64_t DataSize;
621 
622  CharUnits NonVirtualSize;
623  CharUnits NonVirtualAlignment;
624 
625  /// PrimaryBase - the primary base class (if one exists) of the class
626  /// we're laying out.
627  const CXXRecordDecl *PrimaryBase;
628 
629  /// PrimaryBaseIsVirtual - Whether the primary base of the class we're laying
630  /// out is virtual.
631  bool PrimaryBaseIsVirtual;
632 
633  /// HasOwnVFPtr - Whether the class provides its own vtable/vftbl
634  /// pointer, as opposed to inheriting one from a primary base class.
635  bool HasOwnVFPtr;
636 
637  /// the flag of field offset changing due to packed attribute.
638  bool HasPackedField;
639 
640  typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsetsMapTy;
641 
642  /// Bases - base classes and their offsets in the record.
643  BaseOffsetsMapTy Bases;
644 
645  // VBases - virtual base classes and their offsets in the record.
647 
648  /// IndirectPrimaryBases - Virtual base classes, direct or indirect, that are
649  /// primary base classes for some other direct or indirect base class.
650  CXXIndirectPrimaryBaseSet IndirectPrimaryBases;
651 
652  /// FirstNearlyEmptyVBase - The first nearly empty virtual base class in
653  /// inheritance graph order. Used for determining the primary base class.
654  const CXXRecordDecl *FirstNearlyEmptyVBase;
655 
656  /// VisitedVirtualBases - A set of all the visited virtual bases, used to
657  /// avoid visiting virtual bases more than once.
658  llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBases;
659 
660  /// Valid if UseExternalLayout is true.
661  ExternalLayout External;
662 
663  ItaniumRecordLayoutBuilder(const ASTContext &Context,
664  EmptySubobjectMap *EmptySubobjects)
665  : Context(Context), EmptySubobjects(EmptySubobjects), Size(0),
666  Alignment(CharUnits::One()), UnpackedAlignment(CharUnits::One()),
667  UnadjustedAlignment(CharUnits::One()),
668  UseExternalLayout(false), InferAlignment(false), Packed(false),
669  IsUnion(false), IsMac68kAlign(false), IsMsStruct(false),
670  UnfilledBitsInLastUnit(0), LastBitfieldTypeSize(0),
671  MaxFieldAlignment(CharUnits::Zero()), DataSize(0),
672  NonVirtualSize(CharUnits::Zero()),
673  NonVirtualAlignment(CharUnits::One()), PrimaryBase(nullptr),
674  PrimaryBaseIsVirtual(false), HasOwnVFPtr(false),
675  HasPackedField(false), FirstNearlyEmptyVBase(nullptr) {}
676 
677  void Layout(const RecordDecl *D);
678  void Layout(const CXXRecordDecl *D);
679  void Layout(const ObjCInterfaceDecl *D);
680 
681  void LayoutFields(const RecordDecl *D);
682  void LayoutField(const FieldDecl *D, bool InsertExtraPadding);
683  void LayoutWideBitField(uint64_t FieldSize, uint64_t TypeSize,
684  bool FieldPacked, const FieldDecl *D);
685  void LayoutBitField(const FieldDecl *D);
686 
687  TargetCXXABI getCXXABI() const {
688  return Context.getTargetInfo().getCXXABI();
689  }
690 
691  /// BaseSubobjectInfoAllocator - Allocator for BaseSubobjectInfo objects.
692  llvm::SpecificBumpPtrAllocator<BaseSubobjectInfo> BaseSubobjectInfoAllocator;
693 
694  typedef llvm::DenseMap<const CXXRecordDecl *, BaseSubobjectInfo *>
695  BaseSubobjectInfoMapTy;
696 
697  /// VirtualBaseInfo - Map from all the (direct or indirect) virtual bases
698  /// of the class we're laying out to their base subobject info.
699  BaseSubobjectInfoMapTy VirtualBaseInfo;
700 
701  /// NonVirtualBaseInfo - Map from all the direct non-virtual bases of the
702  /// class we're laying out to their base subobject info.
703  BaseSubobjectInfoMapTy NonVirtualBaseInfo;
704 
705  /// ComputeBaseSubobjectInfo - Compute the base subobject information for the
706  /// bases of the given class.
707  void ComputeBaseSubobjectInfo(const CXXRecordDecl *RD);
708 
709  /// ComputeBaseSubobjectInfo - Compute the base subobject information for a
710  /// single class and all of its base classes.
711  BaseSubobjectInfo *ComputeBaseSubobjectInfo(const CXXRecordDecl *RD,
712  bool IsVirtual,
713  BaseSubobjectInfo *Derived);
714 
715  /// DeterminePrimaryBase - Determine the primary base of the given class.
716  void DeterminePrimaryBase(const CXXRecordDecl *RD);
717 
718  void SelectPrimaryVBase(const CXXRecordDecl *RD);
719 
720  void EnsureVTablePointerAlignment(CharUnits UnpackedBaseAlign);
721 
722  /// LayoutNonVirtualBases - Determines the primary base class (if any) and
723  /// lays it out. Will then proceed to lay out all non-virtual base clasess.
724  void LayoutNonVirtualBases(const CXXRecordDecl *RD);
725 
726  /// LayoutNonVirtualBase - Lays out a single non-virtual base.
727  void LayoutNonVirtualBase(const BaseSubobjectInfo *Base);
728 
729  void AddPrimaryVirtualBaseOffsets(const BaseSubobjectInfo *Info,
730  CharUnits Offset);
731 
732  /// LayoutVirtualBases - Lays out all the virtual bases.
733  void LayoutVirtualBases(const CXXRecordDecl *RD,
734  const CXXRecordDecl *MostDerivedClass);
735 
736  /// LayoutVirtualBase - Lays out a single virtual base.
737  void LayoutVirtualBase(const BaseSubobjectInfo *Base);
738 
739  /// LayoutBase - Will lay out a base and return the offset where it was
740  /// placed, in chars.
741  CharUnits LayoutBase(const BaseSubobjectInfo *Base);
742 
743  /// InitializeLayout - Initialize record layout for the given record decl.
744  void InitializeLayout(const Decl *D);
745 
746  /// FinishLayout - Finalize record layout. Adjust record size based on the
747  /// alignment.
748  void FinishLayout(const NamedDecl *D);
749 
750  void UpdateAlignment(CharUnits NewAlignment, CharUnits UnpackedNewAlignment);
751  void UpdateAlignment(CharUnits NewAlignment) {
752  UpdateAlignment(NewAlignment, NewAlignment);
753  }
754 
755  /// Retrieve the externally-supplied field offset for the given
756  /// field.
757  ///
758  /// \param Field The field whose offset is being queried.
759  /// \param ComputedOffset The offset that we've computed for this field.
760  uint64_t updateExternalFieldOffset(const FieldDecl *Field,
761  uint64_t ComputedOffset);
762 
763  void CheckFieldPadding(uint64_t Offset, uint64_t UnpaddedOffset,
764  uint64_t UnpackedOffset, unsigned UnpackedAlign,
765  bool isPacked, const FieldDecl *D);
766 
767  DiagnosticBuilder Diag(SourceLocation Loc, unsigned DiagID);
768 
769  CharUnits getSize() const {
770  assert(Size % Context.getCharWidth() == 0);
771  return Context.toCharUnitsFromBits(Size);
772  }
773  uint64_t getSizeInBits() const { return Size; }
774 
775  void setSize(CharUnits NewSize) { Size = Context.toBits(NewSize); }
776  void setSize(uint64_t NewSize) { Size = NewSize; }
777 
778  CharUnits getAligment() const { return Alignment; }
779 
780  CharUnits getDataSize() const {
781  assert(DataSize % Context.getCharWidth() == 0);
782  return Context.toCharUnitsFromBits(DataSize);
783  }
784  uint64_t getDataSizeInBits() const { return DataSize; }
785 
786  void setDataSize(CharUnits NewSize) { DataSize = Context.toBits(NewSize); }
787  void setDataSize(uint64_t NewSize) { DataSize = NewSize; }
788 
789  ItaniumRecordLayoutBuilder(const ItaniumRecordLayoutBuilder &) = delete;
790  void operator=(const ItaniumRecordLayoutBuilder &) = delete;
791 };
792 } // end anonymous namespace
793 
794 void ItaniumRecordLayoutBuilder::SelectPrimaryVBase(const CXXRecordDecl *RD) {
795  for (const auto &I : RD->bases()) {
796  assert(!I.getType()->isDependentType() &&
797  "Cannot layout class with dependent bases.");
798 
799  const CXXRecordDecl *Base = I.getType()->getAsCXXRecordDecl();
800 
801  // Check if this is a nearly empty virtual base.
802  if (I.isVirtual() && Context.isNearlyEmpty(Base)) {
803  // If it's not an indirect primary base, then we've found our primary
804  // base.
805  if (!IndirectPrimaryBases.count(Base)) {
806  PrimaryBase = Base;
807  PrimaryBaseIsVirtual = true;
808  return;
809  }
810 
811  // Is this the first nearly empty virtual base?
812  if (!FirstNearlyEmptyVBase)
813  FirstNearlyEmptyVBase = Base;
814  }
815 
816  SelectPrimaryVBase(Base);
817  if (PrimaryBase)
818  return;
819  }
820 }
821 
822 /// DeterminePrimaryBase - Determine the primary base of the given class.
823 void ItaniumRecordLayoutBuilder::DeterminePrimaryBase(const CXXRecordDecl *RD) {
824  // If the class isn't dynamic, it won't have a primary base.
825  if (!RD->isDynamicClass())
826  return;
827 
828  // Compute all the primary virtual bases for all of our direct and
829  // indirect bases, and record all their primary virtual base classes.
830  RD->getIndirectPrimaryBases(IndirectPrimaryBases);
831 
832  // If the record has a dynamic base class, attempt to choose a primary base
833  // class. It is the first (in direct base class order) non-virtual dynamic
834  // base class, if one exists.
835  for (const auto &I : RD->bases()) {
836  // Ignore virtual bases.
837  if (I.isVirtual())
838  continue;
839 
840  const CXXRecordDecl *Base = I.getType()->getAsCXXRecordDecl();
841 
842  if (Base->isDynamicClass()) {
843  // We found it.
844  PrimaryBase = Base;
845  PrimaryBaseIsVirtual = false;
846  return;
847  }
848  }
849 
850  // Under the Itanium ABI, if there is no non-virtual primary base class,
851  // try to compute the primary virtual base. The primary virtual base is
852  // the first nearly empty virtual base that is not an indirect primary
853  // virtual base class, if one exists.
854  if (RD->getNumVBases() != 0) {
855  SelectPrimaryVBase(RD);
856  if (PrimaryBase)
857  return;
858  }
859 
860  // Otherwise, it is the first indirect primary base class, if one exists.
861  if (FirstNearlyEmptyVBase) {
862  PrimaryBase = FirstNearlyEmptyVBase;
863  PrimaryBaseIsVirtual = true;
864  return;
865  }
866 
867  assert(!PrimaryBase && "Should not get here with a primary base!");
868 }
869 
870 BaseSubobjectInfo *ItaniumRecordLayoutBuilder::ComputeBaseSubobjectInfo(
871  const CXXRecordDecl *RD, bool IsVirtual, BaseSubobjectInfo *Derived) {
872  BaseSubobjectInfo *Info;
873 
874  if (IsVirtual) {
875  // Check if we already have info about this virtual base.
876  BaseSubobjectInfo *&InfoSlot = VirtualBaseInfo[RD];
877  if (InfoSlot) {
878  assert(InfoSlot->Class == RD && "Wrong class for virtual base info!");
879  return InfoSlot;
880  }
881 
882  // We don't, create it.
883  InfoSlot = new (BaseSubobjectInfoAllocator.Allocate()) BaseSubobjectInfo;
884  Info = InfoSlot;
885  } else {
886  Info = new (BaseSubobjectInfoAllocator.Allocate()) BaseSubobjectInfo;
887  }
888 
889  Info->Class = RD;
890  Info->IsVirtual = IsVirtual;
891  Info->Derived = nullptr;
892  Info->PrimaryVirtualBaseInfo = nullptr;
893 
894  const CXXRecordDecl *PrimaryVirtualBase = nullptr;
895  BaseSubobjectInfo *PrimaryVirtualBaseInfo = nullptr;
896 
897  // Check if this base has a primary virtual base.
898  if (RD->getNumVBases()) {
899  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
900  if (Layout.isPrimaryBaseVirtual()) {
901  // This base does have a primary virtual base.
902  PrimaryVirtualBase = Layout.getPrimaryBase();
903  assert(PrimaryVirtualBase && "Didn't have a primary virtual base!");
904 
905  // Now check if we have base subobject info about this primary base.
906  PrimaryVirtualBaseInfo = VirtualBaseInfo.lookup(PrimaryVirtualBase);
907 
908  if (PrimaryVirtualBaseInfo) {
909  if (PrimaryVirtualBaseInfo->Derived) {
910  // We did have info about this primary base, and it turns out that it
911  // has already been claimed as a primary virtual base for another
912  // base.
913  PrimaryVirtualBase = nullptr;
914  } else {
915  // We can claim this base as our primary base.
916  Info->PrimaryVirtualBaseInfo = PrimaryVirtualBaseInfo;
917  PrimaryVirtualBaseInfo->Derived = Info;
918  }
919  }
920  }
921  }
922 
923  // Now go through all direct bases.
924  for (const auto &I : RD->bases()) {
925  bool IsVirtual = I.isVirtual();
926 
927  const CXXRecordDecl *BaseDecl = I.getType()->getAsCXXRecordDecl();
928 
929  Info->Bases.push_back(ComputeBaseSubobjectInfo(BaseDecl, IsVirtual, Info));
930  }
931 
932  if (PrimaryVirtualBase && !PrimaryVirtualBaseInfo) {
933  // Traversing the bases must have created the base info for our primary
934  // virtual base.
935  PrimaryVirtualBaseInfo = VirtualBaseInfo.lookup(PrimaryVirtualBase);
936  assert(PrimaryVirtualBaseInfo &&
937  "Did not create a primary virtual base!");
938 
939  // Claim the primary virtual base as our primary virtual base.
940  Info->PrimaryVirtualBaseInfo = PrimaryVirtualBaseInfo;
941  PrimaryVirtualBaseInfo->Derived = Info;
942  }
943 
944  return Info;
945 }
946 
947 void ItaniumRecordLayoutBuilder::ComputeBaseSubobjectInfo(
948  const CXXRecordDecl *RD) {
949  for (const auto &I : RD->bases()) {
950  bool IsVirtual = I.isVirtual();
951 
952  const CXXRecordDecl *BaseDecl = I.getType()->getAsCXXRecordDecl();
953 
954  // Compute the base subobject info for this base.
955  BaseSubobjectInfo *Info = ComputeBaseSubobjectInfo(BaseDecl, IsVirtual,
956  nullptr);
957 
958  if (IsVirtual) {
959  // ComputeBaseInfo has already added this base for us.
960  assert(VirtualBaseInfo.count(BaseDecl) &&
961  "Did not add virtual base!");
962  } else {
963  // Add the base info to the map of non-virtual bases.
964  assert(!NonVirtualBaseInfo.count(BaseDecl) &&
965  "Non-virtual base already exists!");
966  NonVirtualBaseInfo.insert(std::make_pair(BaseDecl, Info));
967  }
968  }
969 }
970 
971 void ItaniumRecordLayoutBuilder::EnsureVTablePointerAlignment(
972  CharUnits UnpackedBaseAlign) {
973  CharUnits BaseAlign = Packed ? CharUnits::One() : UnpackedBaseAlign;
974 
975  // The maximum field alignment overrides base align.
976  if (!MaxFieldAlignment.isZero()) {
977  BaseAlign = std::min(BaseAlign, MaxFieldAlignment);
978  UnpackedBaseAlign = std::min(UnpackedBaseAlign, MaxFieldAlignment);
979  }
980 
981  // Round up the current record size to pointer alignment.
982  setSize(getSize().alignTo(BaseAlign));
983  setDataSize(getSize());
984 
985  // Update the alignment.
986  UpdateAlignment(BaseAlign, UnpackedBaseAlign);
987 }
988 
989 void ItaniumRecordLayoutBuilder::LayoutNonVirtualBases(
990  const CXXRecordDecl *RD) {
991  // Then, determine the primary base class.
992  DeterminePrimaryBase(RD);
993 
994  // Compute base subobject info.
995  ComputeBaseSubobjectInfo(RD);
996 
997  // If we have a primary base class, lay it out.
998  if (PrimaryBase) {
999  if (PrimaryBaseIsVirtual) {
1000  // If the primary virtual base was a primary virtual base of some other
1001  // base class we'll have to steal it.
1002  BaseSubobjectInfo *PrimaryBaseInfo = VirtualBaseInfo.lookup(PrimaryBase);
1003  PrimaryBaseInfo->Derived = nullptr;
1004 
1005  // We have a virtual primary base, insert it as an indirect primary base.
1006  IndirectPrimaryBases.insert(PrimaryBase);
1007 
1008  assert(!VisitedVirtualBases.count(PrimaryBase) &&
1009  "vbase already visited!");
1010  VisitedVirtualBases.insert(PrimaryBase);
1011 
1012  LayoutVirtualBase(PrimaryBaseInfo);
1013  } else {
1014  BaseSubobjectInfo *PrimaryBaseInfo =
1015  NonVirtualBaseInfo.lookup(PrimaryBase);
1016  assert(PrimaryBaseInfo &&
1017  "Did not find base info for non-virtual primary base!");
1018 
1019  LayoutNonVirtualBase(PrimaryBaseInfo);
1020  }
1021 
1022  // If this class needs a vtable/vf-table and didn't get one from a
1023  // primary base, add it in now.
1024  } else if (RD->isDynamicClass()) {
1025  assert(DataSize == 0 && "Vtable pointer must be at offset zero!");
1026  CharUnits PtrWidth =
1027  Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
1028  CharUnits PtrAlign =
1029  Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerAlign(0));
1030  EnsureVTablePointerAlignment(PtrAlign);
1031  HasOwnVFPtr = true;
1032  setSize(getSize() + PtrWidth);
1033  setDataSize(getSize());
1034  }
1035 
1036  // Now lay out the non-virtual bases.
1037  for (const auto &I : RD->bases()) {
1038 
1039  // Ignore virtual bases.
1040  if (I.isVirtual())
1041  continue;
1042 
1043  const CXXRecordDecl *BaseDecl = I.getType()->getAsCXXRecordDecl();
1044 
1045  // Skip the primary base, because we've already laid it out. The
1046  // !PrimaryBaseIsVirtual check is required because we might have a
1047  // non-virtual base of the same type as a primary virtual base.
1048  if (BaseDecl == PrimaryBase && !PrimaryBaseIsVirtual)
1049  continue;
1050 
1051  // Lay out the base.
1052  BaseSubobjectInfo *BaseInfo = NonVirtualBaseInfo.lookup(BaseDecl);
1053  assert(BaseInfo && "Did not find base info for non-virtual base!");
1054 
1055  LayoutNonVirtualBase(BaseInfo);
1056  }
1057 }
1058 
1059 void ItaniumRecordLayoutBuilder::LayoutNonVirtualBase(
1060  const BaseSubobjectInfo *Base) {
1061  // Layout the base.
1062  CharUnits Offset = LayoutBase(Base);
1063 
1064  // Add its base class offset.
1065  assert(!Bases.count(Base->Class) && "base offset already exists!");
1066  Bases.insert(std::make_pair(Base->Class, Offset));
1067 
1068  AddPrimaryVirtualBaseOffsets(Base, Offset);
1069 }
1070 
1071 void ItaniumRecordLayoutBuilder::AddPrimaryVirtualBaseOffsets(
1072  const BaseSubobjectInfo *Info, CharUnits Offset) {
1073  // This base isn't interesting, it has no virtual bases.
1074  if (!Info->Class->getNumVBases())
1075  return;
1076 
1077  // First, check if we have a virtual primary base to add offsets for.
1078  if (Info->PrimaryVirtualBaseInfo) {
1079  assert(Info->PrimaryVirtualBaseInfo->IsVirtual &&
1080  "Primary virtual base is not virtual!");
1081  if (Info->PrimaryVirtualBaseInfo->Derived == Info) {
1082  // Add the offset.
1083  assert(!VBases.count(Info->PrimaryVirtualBaseInfo->Class) &&
1084  "primary vbase offset already exists!");
1085  VBases.insert(std::make_pair(Info->PrimaryVirtualBaseInfo->Class,
1086  ASTRecordLayout::VBaseInfo(Offset, false)));
1087 
1088  // Traverse the primary virtual base.
1089  AddPrimaryVirtualBaseOffsets(Info->PrimaryVirtualBaseInfo, Offset);
1090  }
1091  }
1092 
1093  // Now go through all direct non-virtual bases.
1094  const ASTRecordLayout &Layout = Context.getASTRecordLayout(Info->Class);
1095  for (const BaseSubobjectInfo *Base : Info->Bases) {
1096  if (Base->IsVirtual)
1097  continue;
1098 
1099  CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base->Class);
1100  AddPrimaryVirtualBaseOffsets(Base, BaseOffset);
1101  }
1102 }
1103 
1104 void ItaniumRecordLayoutBuilder::LayoutVirtualBases(
1105  const CXXRecordDecl *RD, const CXXRecordDecl *MostDerivedClass) {
1106  const CXXRecordDecl *PrimaryBase;
1107  bool PrimaryBaseIsVirtual;
1108 
1109  if (MostDerivedClass == RD) {
1110  PrimaryBase = this->PrimaryBase;
1111  PrimaryBaseIsVirtual = this->PrimaryBaseIsVirtual;
1112  } else {
1113  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1114  PrimaryBase = Layout.getPrimaryBase();
1115  PrimaryBaseIsVirtual = Layout.isPrimaryBaseVirtual();
1116  }
1117 
1118  for (const CXXBaseSpecifier &Base : RD->bases()) {
1119  assert(!Base.getType()->isDependentType() &&
1120  "Cannot layout class with dependent bases.");
1121 
1122  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
1123 
1124  if (Base.isVirtual()) {
1125  if (PrimaryBase != BaseDecl || !PrimaryBaseIsVirtual) {
1126  bool IndirectPrimaryBase = IndirectPrimaryBases.count(BaseDecl);
1127 
1128  // Only lay out the virtual base if it's not an indirect primary base.
1129  if (!IndirectPrimaryBase) {
1130  // Only visit virtual bases once.
1131  if (!VisitedVirtualBases.insert(BaseDecl).second)
1132  continue;
1133 
1134  const BaseSubobjectInfo *BaseInfo = VirtualBaseInfo.lookup(BaseDecl);
1135  assert(BaseInfo && "Did not find virtual base info!");
1136  LayoutVirtualBase(BaseInfo);
1137  }
1138  }
1139  }
1140 
1141  if (!BaseDecl->getNumVBases()) {
1142  // This base isn't interesting since it doesn't have any virtual bases.
1143  continue;
1144  }
1145 
1146  LayoutVirtualBases(BaseDecl, MostDerivedClass);
1147  }
1148 }
1149 
1150 void ItaniumRecordLayoutBuilder::LayoutVirtualBase(
1151  const BaseSubobjectInfo *Base) {
1152  assert(!Base->Derived && "Trying to lay out a primary virtual base!");
1153 
1154  // Layout the base.
1155  CharUnits Offset = LayoutBase(Base);
1156 
1157  // Add its base class offset.
1158  assert(!VBases.count(Base->Class) && "vbase offset already exists!");
1159  VBases.insert(std::make_pair(Base->Class,
1160  ASTRecordLayout::VBaseInfo(Offset, false)));
1161 
1162  AddPrimaryVirtualBaseOffsets(Base, Offset);
1163 }
1164 
1165 CharUnits
1166 ItaniumRecordLayoutBuilder::LayoutBase(const BaseSubobjectInfo *Base) {
1167  const ASTRecordLayout &Layout = Context.getASTRecordLayout(Base->Class);
1168 
1169 
1170  CharUnits Offset;
1171 
1172  // Query the external layout to see if it provides an offset.
1173  bool HasExternalLayout = false;
1174  if (UseExternalLayout) {
1175  if (Base->IsVirtual)
1176  HasExternalLayout = External.getExternalNVBaseOffset(Base->Class, Offset);
1177  else
1178  HasExternalLayout = External.getExternalVBaseOffset(Base->Class, Offset);
1179  }
1180 
1181  // Clang <= 6 incorrectly applied the 'packed' attribute to base classes.
1182  // Per GCC's documentation, it only applies to non-static data members.
1183  CharUnits UnpackedBaseAlign = Layout.getNonVirtualAlignment();
1184  CharUnits BaseAlign =
1185  (Packed && ((Context.getLangOpts().getClangABICompat() <=
1187  Context.getTargetInfo().getTriple().isPS4()))
1188  ? CharUnits::One()
1189  : UnpackedBaseAlign;
1190 
1191  // If we have an empty base class, try to place it at offset 0.
1192  if (Base->Class->isEmpty() &&
1193  (!HasExternalLayout || Offset == CharUnits::Zero()) &&
1194  EmptySubobjects->CanPlaceBaseAtOffset(Base, CharUnits::Zero())) {
1195  setSize(std::max(getSize(), Layout.getSize()));
1196  UpdateAlignment(BaseAlign, UnpackedBaseAlign);
1197 
1198  return CharUnits::Zero();
1199  }
1200 
1201  // The maximum field alignment overrides base align.
1202  if (!MaxFieldAlignment.isZero()) {
1203  BaseAlign = std::min(BaseAlign, MaxFieldAlignment);
1204  UnpackedBaseAlign = std::min(UnpackedBaseAlign, MaxFieldAlignment);
1205  }
1206 
1207  if (!HasExternalLayout) {
1208  // Round up the current record size to the base's alignment boundary.
1209  Offset = getDataSize().alignTo(BaseAlign);
1210 
1211  // Try to place the base.
1212  while (!EmptySubobjects->CanPlaceBaseAtOffset(Base, Offset))
1213  Offset += BaseAlign;
1214  } else {
1215  bool Allowed = EmptySubobjects->CanPlaceBaseAtOffset(Base, Offset);
1216  (void)Allowed;
1217  assert(Allowed && "Base subobject externally placed at overlapping offset");
1218 
1219  if (InferAlignment && Offset < getDataSize().alignTo(BaseAlign)) {
1220  // The externally-supplied base offset is before the base offset we
1221  // computed. Assume that the structure is packed.
1222  Alignment = CharUnits::One();
1223  InferAlignment = false;
1224  }
1225  }
1226 
1227  if (!Base->Class->isEmpty()) {
1228  // Update the data size.
1229  setDataSize(Offset + Layout.getNonVirtualSize());
1230 
1231  setSize(std::max(getSize(), getDataSize()));
1232  } else
1233  setSize(std::max(getSize(), Offset + Layout.getSize()));
1234 
1235  // Remember max struct/class alignment.
1236  UpdateAlignment(BaseAlign, UnpackedBaseAlign);
1237 
1238  return Offset;
1239 }
1240 
1241 void ItaniumRecordLayoutBuilder::InitializeLayout(const Decl *D) {
1242  if (const RecordDecl *RD = dyn_cast<RecordDecl>(D)) {
1243  IsUnion = RD->isUnion();
1244  IsMsStruct = RD->isMsStruct(Context);
1245  }
1246 
1247  Packed = D->hasAttr<PackedAttr>();
1248 
1249  // Honor the default struct packing maximum alignment flag.
1250  if (unsigned DefaultMaxFieldAlignment = Context.getLangOpts().PackStruct) {
1251  MaxFieldAlignment = CharUnits::fromQuantity(DefaultMaxFieldAlignment);
1252  }
1253 
1254  // mac68k alignment supersedes maximum field alignment and attribute aligned,
1255  // and forces all structures to have 2-byte alignment. The IBM docs on it
1256  // allude to additional (more complicated) semantics, especially with regard
1257  // to bit-fields, but gcc appears not to follow that.
1258  if (D->hasAttr<AlignMac68kAttr>()) {
1259  IsMac68kAlign = true;
1260  MaxFieldAlignment = CharUnits::fromQuantity(2);
1261  Alignment = CharUnits::fromQuantity(2);
1262  } else {
1263  if (const MaxFieldAlignmentAttr *MFAA = D->getAttr<MaxFieldAlignmentAttr>())
1264  MaxFieldAlignment = Context.toCharUnitsFromBits(MFAA->getAlignment());
1265 
1266  if (unsigned MaxAlign = D->getMaxAlignment())
1267  UpdateAlignment(Context.toCharUnitsFromBits(MaxAlign));
1268  }
1269 
1270  // If there is an external AST source, ask it for the various offsets.
1271  if (const RecordDecl *RD = dyn_cast<RecordDecl>(D))
1272  if (ExternalASTSource *Source = Context.getExternalSource()) {
1273  UseExternalLayout = Source->layoutRecordType(
1274  RD, External.Size, External.Align, External.FieldOffsets,
1275  External.BaseOffsets, External.VirtualBaseOffsets);
1276 
1277  // Update based on external alignment.
1278  if (UseExternalLayout) {
1279  if (External.Align > 0) {
1280  Alignment = Context.toCharUnitsFromBits(External.Align);
1281  } else {
1282  // The external source didn't have alignment information; infer it.
1283  InferAlignment = true;
1284  }
1285  }
1286  }
1287 }
1288 
1289 void ItaniumRecordLayoutBuilder::Layout(const RecordDecl *D) {
1290  InitializeLayout(D);
1291  LayoutFields(D);
1292 
1293  // Finally, round the size of the total struct up to the alignment of the
1294  // struct itself.
1295  FinishLayout(D);
1296 }
1297 
1298 void ItaniumRecordLayoutBuilder::Layout(const CXXRecordDecl *RD) {
1299  InitializeLayout(RD);
1300 
1301  // Lay out the vtable and the non-virtual bases.
1302  LayoutNonVirtualBases(RD);
1303 
1304  LayoutFields(RD);
1305 
1306  NonVirtualSize = Context.toCharUnitsFromBits(
1307  llvm::alignTo(getSizeInBits(), Context.getTargetInfo().getCharAlign()));
1308  NonVirtualAlignment = Alignment;
1309 
1310  // Lay out the virtual bases and add the primary virtual base offsets.
1311  LayoutVirtualBases(RD, RD);
1312 
1313  // Finally, round the size of the total struct up to the alignment
1314  // of the struct itself.
1315  FinishLayout(RD);
1316 
1317 #ifndef NDEBUG
1318  // Check that we have base offsets for all bases.
1319  for (const CXXBaseSpecifier &Base : RD->bases()) {
1320  if (Base.isVirtual())
1321  continue;
1322 
1323  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
1324 
1325  assert(Bases.count(BaseDecl) && "Did not find base offset!");
1326  }
1327 
1328  // And all virtual bases.
1329  for (const CXXBaseSpecifier &Base : RD->vbases()) {
1330  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
1331 
1332  assert(VBases.count(BaseDecl) && "Did not find base offset!");
1333  }
1334 #endif
1335 }
1336 
1337 void ItaniumRecordLayoutBuilder::Layout(const ObjCInterfaceDecl *D) {
1338  if (ObjCInterfaceDecl *SD = D->getSuperClass()) {
1339  const ASTRecordLayout &SL = Context.getASTObjCInterfaceLayout(SD);
1340 
1341  UpdateAlignment(SL.getAlignment());
1342 
1343  // We start laying out ivars not at the end of the superclass
1344  // structure, but at the next byte following the last field.
1345  setSize(SL.getDataSize());
1346  setDataSize(getSize());
1347  }
1348 
1349  InitializeLayout(D);
1350  // Layout each ivar sequentially.
1351  for (const ObjCIvarDecl *IVD = D->all_declared_ivar_begin(); IVD;
1352  IVD = IVD->getNextIvar())
1353  LayoutField(IVD, false);
1354 
1355  // Finally, round the size of the total struct up to the alignment of the
1356  // struct itself.
1357  FinishLayout(D);
1358 }
1359 
1360 void ItaniumRecordLayoutBuilder::LayoutFields(const RecordDecl *D) {
1361  // Layout each field, for now, just sequentially, respecting alignment. In
1362  // the future, this will need to be tweakable by targets.
1363  bool InsertExtraPadding = D->mayInsertExtraPadding(/*EmitRemark=*/true);
1364  bool HasFlexibleArrayMember = D->hasFlexibleArrayMember();
1365  for (auto I = D->field_begin(), End = D->field_end(); I != End; ++I) {
1366  auto Next(I);
1367  ++Next;
1368  LayoutField(*I,
1369  InsertExtraPadding && (Next != End || !HasFlexibleArrayMember));
1370  }
1371 }
1372 
1373 // Rounds the specified size to have it a multiple of the char size.
1374 static uint64_t
1376  const ASTContext &Context) {
1377  uint64_t CharAlignment = Context.getTargetInfo().getCharAlign();
1378  return llvm::alignTo(Size, CharAlignment);
1379 }
1380 
1381 void ItaniumRecordLayoutBuilder::LayoutWideBitField(uint64_t FieldSize,
1382  uint64_t TypeSize,
1383  bool FieldPacked,
1384  const FieldDecl *D) {
1385  assert(Context.getLangOpts().CPlusPlus &&
1386  "Can only have wide bit-fields in C++!");
1387 
1388  // Itanium C++ ABI 2.4:
1389  // If sizeof(T)*8 < n, let T' be the largest integral POD type with
1390  // sizeof(T')*8 <= n.
1391 
1392  QualType IntegralPODTypes[] = {
1393  Context.UnsignedCharTy, Context.UnsignedShortTy, Context.UnsignedIntTy,
1394  Context.UnsignedLongTy, Context.UnsignedLongLongTy
1395  };
1396 
1397  QualType Type;
1398  for (const QualType &QT : IntegralPODTypes) {
1399  uint64_t Size = Context.getTypeSize(QT);
1400 
1401  if (Size > FieldSize)
1402  break;
1403 
1404  Type = QT;
1405  }
1406  assert(!Type.isNull() && "Did not find a type!");
1407 
1408  CharUnits TypeAlign = Context.getTypeAlignInChars(Type);
1409 
1410  // We're not going to use any of the unfilled bits in the last byte.
1411  UnfilledBitsInLastUnit = 0;
1412  LastBitfieldTypeSize = 0;
1413 
1414  uint64_t FieldOffset;
1415  uint64_t UnpaddedFieldOffset = getDataSizeInBits() - UnfilledBitsInLastUnit;
1416 
1417  if (IsUnion) {
1418  uint64_t RoundedFieldSize = roundUpSizeToCharAlignment(FieldSize,
1419  Context);
1420  setDataSize(std::max(getDataSizeInBits(), RoundedFieldSize));
1421  FieldOffset = 0;
1422  } else {
1423  // The bitfield is allocated starting at the next offset aligned
1424  // appropriately for T', with length n bits.
1425  FieldOffset = llvm::alignTo(getDataSizeInBits(), Context.toBits(TypeAlign));
1426 
1427  uint64_t NewSizeInBits = FieldOffset + FieldSize;
1428 
1429  setDataSize(
1430  llvm::alignTo(NewSizeInBits, Context.getTargetInfo().getCharAlign()));
1431  UnfilledBitsInLastUnit = getDataSizeInBits() - NewSizeInBits;
1432  }
1433 
1434  // Place this field at the current location.
1435  FieldOffsets.push_back(FieldOffset);
1436 
1437  CheckFieldPadding(FieldOffset, UnpaddedFieldOffset, FieldOffset,
1438  Context.toBits(TypeAlign), FieldPacked, D);
1439 
1440  // Update the size.
1441  setSize(std::max(getSizeInBits(), getDataSizeInBits()));
1442 
1443  // Remember max struct/class alignment.
1444  UpdateAlignment(TypeAlign);
1445 }
1446 
1447 void ItaniumRecordLayoutBuilder::LayoutBitField(const FieldDecl *D) {
1448  bool FieldPacked = Packed || D->hasAttr<PackedAttr>();
1449  uint64_t FieldSize = D->getBitWidthValue(Context);
1450  TypeInfo FieldInfo = Context.getTypeInfo(D->getType());
1451  uint64_t TypeSize = FieldInfo.Width;
1452  unsigned FieldAlign = FieldInfo.Align;
1453 
1454  // UnfilledBitsInLastUnit is the difference between the end of the
1455  // last allocated bitfield (i.e. the first bit offset available for
1456  // bitfields) and the end of the current data size in bits (i.e. the
1457  // first bit offset available for non-bitfields). The current data
1458  // size in bits is always a multiple of the char size; additionally,
1459  // for ms_struct records it's also a multiple of the
1460  // LastBitfieldTypeSize (if set).
1461 
1462  // The struct-layout algorithm is dictated by the platform ABI,
1463  // which in principle could use almost any rules it likes. In
1464  // practice, UNIXy targets tend to inherit the algorithm described
1465  // in the System V generic ABI. The basic bitfield layout rule in
1466  // System V is to place bitfields at the next available bit offset
1467  // where the entire bitfield would fit in an aligned storage unit of
1468  // the declared type; it's okay if an earlier or later non-bitfield
1469  // is allocated in the same storage unit. However, some targets
1470  // (those that !useBitFieldTypeAlignment(), e.g. ARM APCS) don't
1471  // require this storage unit to be aligned, and therefore always put
1472  // the bitfield at the next available bit offset.
1473 
1474  // ms_struct basically requests a complete replacement of the
1475  // platform ABI's struct-layout algorithm, with the high-level goal
1476  // of duplicating MSVC's layout. For non-bitfields, this follows
1477  // the standard algorithm. The basic bitfield layout rule is to
1478  // allocate an entire unit of the bitfield's declared type
1479  // (e.g. 'unsigned long'), then parcel it up among successive
1480  // bitfields whose declared types have the same size, making a new
1481  // unit as soon as the last can no longer store the whole value.
1482  // Since it completely replaces the platform ABI's algorithm,
1483  // settings like !useBitFieldTypeAlignment() do not apply.
1484 
1485  // A zero-width bitfield forces the use of a new storage unit for
1486  // later bitfields. In general, this occurs by rounding up the
1487  // current size of the struct as if the algorithm were about to
1488  // place a non-bitfield of the field's formal type. Usually this
1489  // does not change the alignment of the struct itself, but it does
1490  // on some targets (those that useZeroLengthBitfieldAlignment(),
1491  // e.g. ARM). In ms_struct layout, zero-width bitfields are
1492  // ignored unless they follow a non-zero-width bitfield.
1493 
1494  // A field alignment restriction (e.g. from #pragma pack) or
1495  // specification (e.g. from __attribute__((aligned))) changes the
1496  // formal alignment of the field. For System V, this alters the
1497  // required alignment of the notional storage unit that must contain
1498  // the bitfield. For ms_struct, this only affects the placement of
1499  // new storage units. In both cases, the effect of #pragma pack is
1500  // ignored on zero-width bitfields.
1501 
1502  // On System V, a packed field (e.g. from #pragma pack or
1503  // __attribute__((packed))) always uses the next available bit
1504  // offset.
1505 
1506  // In an ms_struct struct, the alignment of a fundamental type is
1507  // always equal to its size. This is necessary in order to mimic
1508  // the i386 alignment rules on targets which might not fully align
1509  // all types (e.g. Darwin PPC32, where alignof(long long) == 4).
1510 
1511  // First, some simple bookkeeping to perform for ms_struct structs.
1512  if (IsMsStruct) {
1513  // The field alignment for integer types is always the size.
1514  FieldAlign = TypeSize;
1515 
1516  // If the previous field was not a bitfield, or was a bitfield
1517  // with a different storage unit size, or if this field doesn't fit into
1518  // the current storage unit, we're done with that storage unit.
1519  if (LastBitfieldTypeSize != TypeSize ||
1520  UnfilledBitsInLastUnit < FieldSize) {
1521  // Also, ignore zero-length bitfields after non-bitfields.
1522  if (!LastBitfieldTypeSize && !FieldSize)
1523  FieldAlign = 1;
1524 
1525  UnfilledBitsInLastUnit = 0;
1526  LastBitfieldTypeSize = 0;
1527  }
1528  }
1529 
1530  // If the field is wider than its declared type, it follows
1531  // different rules in all cases.
1532  if (FieldSize > TypeSize) {
1533  LayoutWideBitField(FieldSize, TypeSize, FieldPacked, D);
1534  return;
1535  }
1536 
1537  // Compute the next available bit offset.
1538  uint64_t FieldOffset =
1539  IsUnion ? 0 : (getDataSizeInBits() - UnfilledBitsInLastUnit);
1540 
1541  // Handle targets that don't honor bitfield type alignment.
1542  if (!IsMsStruct && !Context.getTargetInfo().useBitFieldTypeAlignment()) {
1543  // Some such targets do honor it on zero-width bitfields.
1544  if (FieldSize == 0 &&
1546  // The alignment to round up to is the max of the field's natural
1547  // alignment and a target-specific fixed value (sometimes zero).
1548  unsigned ZeroLengthBitfieldBoundary =
1550  FieldAlign = std::max(FieldAlign, ZeroLengthBitfieldBoundary);
1551 
1552  // If that doesn't apply, just ignore the field alignment.
1553  } else {
1554  FieldAlign = 1;
1555  }
1556  }
1557 
1558  // Remember the alignment we would have used if the field were not packed.
1559  unsigned UnpackedFieldAlign = FieldAlign;
1560 
1561  // Ignore the field alignment if the field is packed unless it has zero-size.
1562  if (!IsMsStruct && FieldPacked && FieldSize != 0)
1563  FieldAlign = 1;
1564 
1565  // But, if there's an 'aligned' attribute on the field, honor that.
1566  unsigned ExplicitFieldAlign = D->getMaxAlignment();
1567  if (ExplicitFieldAlign) {
1568  FieldAlign = std::max(FieldAlign, ExplicitFieldAlign);
1569  UnpackedFieldAlign = std::max(UnpackedFieldAlign, ExplicitFieldAlign);
1570  }
1571 
1572  // But, if there's a #pragma pack in play, that takes precedent over
1573  // even the 'aligned' attribute, for non-zero-width bitfields.
1574  unsigned MaxFieldAlignmentInBits = Context.toBits(MaxFieldAlignment);
1575  if (!MaxFieldAlignment.isZero() && FieldSize) {
1576  UnpackedFieldAlign = std::min(UnpackedFieldAlign, MaxFieldAlignmentInBits);
1577  if (FieldPacked)
1578  FieldAlign = UnpackedFieldAlign;
1579  else
1580  FieldAlign = std::min(FieldAlign, MaxFieldAlignmentInBits);
1581  }
1582 
1583  // But, ms_struct just ignores all of that in unions, even explicit
1584  // alignment attributes.
1585  if (IsMsStruct && IsUnion) {
1586  FieldAlign = UnpackedFieldAlign = 1;
1587  }
1588 
1589  // For purposes of diagnostics, we're going to simultaneously
1590  // compute the field offsets that we would have used if we weren't
1591  // adding any alignment padding or if the field weren't packed.
1592  uint64_t UnpaddedFieldOffset = FieldOffset;
1593  uint64_t UnpackedFieldOffset = FieldOffset;
1594 
1595  // Check if we need to add padding to fit the bitfield within an
1596  // allocation unit with the right size and alignment. The rules are
1597  // somewhat different here for ms_struct structs.
1598  if (IsMsStruct) {
1599  // If it's not a zero-width bitfield, and we can fit the bitfield
1600  // into the active storage unit (and we haven't already decided to
1601  // start a new storage unit), just do so, regardless of any other
1602  // other consideration. Otherwise, round up to the right alignment.
1603  if (FieldSize == 0 || FieldSize > UnfilledBitsInLastUnit) {
1604  FieldOffset = llvm::alignTo(FieldOffset, FieldAlign);
1605  UnpackedFieldOffset =
1606  llvm::alignTo(UnpackedFieldOffset, UnpackedFieldAlign);
1607  UnfilledBitsInLastUnit = 0;
1608  }
1609 
1610  } else {
1611  // #pragma pack, with any value, suppresses the insertion of padding.
1612  bool AllowPadding = MaxFieldAlignment.isZero();
1613 
1614  // Compute the real offset.
1615  if (FieldSize == 0 ||
1616  (AllowPadding &&
1617  (FieldOffset & (FieldAlign-1)) + FieldSize > TypeSize)) {
1618  FieldOffset = llvm::alignTo(FieldOffset, FieldAlign);
1619  } else if (ExplicitFieldAlign &&
1620  (MaxFieldAlignmentInBits == 0 ||
1621  ExplicitFieldAlign <= MaxFieldAlignmentInBits) &&
1623  // TODO: figure it out what needs to be done on targets that don't honor
1624  // bit-field type alignment like ARM APCS ABI.
1625  FieldOffset = llvm::alignTo(FieldOffset, ExplicitFieldAlign);
1626  }
1627 
1628  // Repeat the computation for diagnostic purposes.
1629  if (FieldSize == 0 ||
1630  (AllowPadding &&
1631  (UnpackedFieldOffset & (UnpackedFieldAlign-1)) + FieldSize > TypeSize))
1632  UnpackedFieldOffset =
1633  llvm::alignTo(UnpackedFieldOffset, UnpackedFieldAlign);
1634  else if (ExplicitFieldAlign &&
1635  (MaxFieldAlignmentInBits == 0 ||
1636  ExplicitFieldAlign <= MaxFieldAlignmentInBits) &&
1638  UnpackedFieldOffset =
1639  llvm::alignTo(UnpackedFieldOffset, ExplicitFieldAlign);
1640  }
1641 
1642  // If we're using external layout, give the external layout a chance
1643  // to override this information.
1644  if (UseExternalLayout)
1645  FieldOffset = updateExternalFieldOffset(D, FieldOffset);
1646 
1647  // Okay, place the bitfield at the calculated offset.
1648  FieldOffsets.push_back(FieldOffset);
1649 
1650  // Bookkeeping:
1651 
1652  // Anonymous members don't affect the overall record alignment,
1653  // except on targets where they do.
1654  if (!IsMsStruct &&
1656  !D->getIdentifier())
1657  FieldAlign = UnpackedFieldAlign = 1;
1658 
1659  // Diagnose differences in layout due to padding or packing.
1660  if (!UseExternalLayout)
1661  CheckFieldPadding(FieldOffset, UnpaddedFieldOffset, UnpackedFieldOffset,
1662  UnpackedFieldAlign, FieldPacked, D);
1663 
1664  // Update DataSize to include the last byte containing (part of) the bitfield.
1665 
1666  // For unions, this is just a max operation, as usual.
1667  if (IsUnion) {
1668  // For ms_struct, allocate the entire storage unit --- unless this
1669  // is a zero-width bitfield, in which case just use a size of 1.
1670  uint64_t RoundedFieldSize;
1671  if (IsMsStruct) {
1672  RoundedFieldSize =
1673  (FieldSize ? TypeSize : Context.getTargetInfo().getCharWidth());
1674 
1675  // Otherwise, allocate just the number of bytes required to store
1676  // the bitfield.
1677  } else {
1678  RoundedFieldSize = roundUpSizeToCharAlignment(FieldSize, Context);
1679  }
1680  setDataSize(std::max(getDataSizeInBits(), RoundedFieldSize));
1681 
1682  // For non-zero-width bitfields in ms_struct structs, allocate a new
1683  // storage unit if necessary.
1684  } else if (IsMsStruct && FieldSize) {
1685  // We should have cleared UnfilledBitsInLastUnit in every case
1686  // where we changed storage units.
1687  if (!UnfilledBitsInLastUnit) {
1688  setDataSize(FieldOffset + TypeSize);
1689  UnfilledBitsInLastUnit = TypeSize;
1690  }
1691  UnfilledBitsInLastUnit -= FieldSize;
1692  LastBitfieldTypeSize = TypeSize;
1693 
1694  // Otherwise, bump the data size up to include the bitfield,
1695  // including padding up to char alignment, and then remember how
1696  // bits we didn't use.
1697  } else {
1698  uint64_t NewSizeInBits = FieldOffset + FieldSize;
1699  uint64_t CharAlignment = Context.getTargetInfo().getCharAlign();
1700  setDataSize(llvm::alignTo(NewSizeInBits, CharAlignment));
1701  UnfilledBitsInLastUnit = getDataSizeInBits() - NewSizeInBits;
1702 
1703  // The only time we can get here for an ms_struct is if this is a
1704  // zero-width bitfield, which doesn't count as anything for the
1705  // purposes of unfilled bits.
1706  LastBitfieldTypeSize = 0;
1707  }
1708 
1709  // Update the size.
1710  setSize(std::max(getSizeInBits(), getDataSizeInBits()));
1711 
1712  // Remember max struct/class alignment.
1713  UnadjustedAlignment =
1714  std::max(UnadjustedAlignment, Context.toCharUnitsFromBits(FieldAlign));
1715  UpdateAlignment(Context.toCharUnitsFromBits(FieldAlign),
1716  Context.toCharUnitsFromBits(UnpackedFieldAlign));
1717 }
1718 
1719 void ItaniumRecordLayoutBuilder::LayoutField(const FieldDecl *D,
1720  bool InsertExtraPadding) {
1721  if (D->isBitField()) {
1722  LayoutBitField(D);
1723  return;
1724  }
1725 
1726  uint64_t UnpaddedFieldOffset = getDataSizeInBits() - UnfilledBitsInLastUnit;
1727 
1728  // Reset the unfilled bits.
1729  UnfilledBitsInLastUnit = 0;
1730  LastBitfieldTypeSize = 0;
1731 
1732  bool FieldPacked = Packed || D->hasAttr<PackedAttr>();
1733  CharUnits FieldOffset =
1734  IsUnion ? CharUnits::Zero() : getDataSize();
1735  CharUnits FieldSize;
1736  CharUnits FieldAlign;
1737 
1738  if (D->getType()->isIncompleteArrayType()) {
1739  // This is a flexible array member; we can't directly
1740  // query getTypeInfo about these, so we figure it out here.
1741  // Flexible array members don't have any size, but they
1742  // have to be aligned appropriately for their element type.
1743  FieldSize = CharUnits::Zero();
1744  const ArrayType* ATy = Context.getAsArrayType(D->getType());
1745  FieldAlign = Context.getTypeAlignInChars(ATy->getElementType());
1746  } else if (const ReferenceType *RT = D->getType()->getAs<ReferenceType>()) {
1747  unsigned AS = Context.getTargetAddressSpace(RT->getPointeeType());
1748  FieldSize =
1749  Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(AS));
1750  FieldAlign =
1751  Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerAlign(AS));
1752  } else {
1753  std::pair<CharUnits, CharUnits> FieldInfo =
1754  Context.getTypeInfoInChars(D->getType());
1755  FieldSize = FieldInfo.first;
1756  FieldAlign = FieldInfo.second;
1757 
1758  if (IsMsStruct) {
1759  // If MS bitfield layout is required, figure out what type is being
1760  // laid out and align the field to the width of that type.
1761 
1762  // Resolve all typedefs down to their base type and round up the field
1763  // alignment if necessary.
1764  QualType T = Context.getBaseElementType(D->getType());
1765  if (const BuiltinType *BTy = T->getAs<BuiltinType>()) {
1766  CharUnits TypeSize = Context.getTypeSizeInChars(BTy);
1767 
1768  if (!llvm::isPowerOf2_64(TypeSize.getQuantity())) {
1769  assert(
1770  !Context.getTargetInfo().getTriple().isWindowsMSVCEnvironment() &&
1771  "Non PowerOf2 size in MSVC mode");
1772  // Base types with sizes that aren't a power of two don't work
1773  // with the layout rules for MS structs. This isn't an issue in
1774  // MSVC itself since there are no such base data types there.
1775  // On e.g. x86_32 mingw and linux, long double is 12 bytes though.
1776  // Any structs involving that data type obviously can't be ABI
1777  // compatible with MSVC regardless of how it is laid out.
1778 
1779  // Since ms_struct can be mass enabled (via a pragma or via the
1780  // -mms-bitfields command line parameter), this can trigger for
1781  // structs that don't actually need MSVC compatibility, so we
1782  // need to be able to sidestep the ms_struct layout for these types.
1783 
1784  // Since the combination of -mms-bitfields together with structs
1785  // like max_align_t (which contains a long double) for mingw is
1786  // quite comon (and GCC handles it silently), just handle it
1787  // silently there. For other targets that have ms_struct enabled
1788  // (most probably via a pragma or attribute), trigger a diagnostic
1789  // that defaults to an error.
1790  if (!Context.getTargetInfo().getTriple().isWindowsGNUEnvironment())
1791  Diag(D->getLocation(), diag::warn_npot_ms_struct);
1792  }
1793  if (TypeSize > FieldAlign &&
1794  llvm::isPowerOf2_64(TypeSize.getQuantity()))
1795  FieldAlign = TypeSize;
1796  }
1797  }
1798  }
1799 
1800  // The align if the field is not packed. This is to check if the attribute
1801  // was unnecessary (-Wpacked).
1802  CharUnits UnpackedFieldAlign = FieldAlign;
1803  CharUnits UnpackedFieldOffset = FieldOffset;
1804 
1805  if (FieldPacked)
1806  FieldAlign = CharUnits::One();
1807  CharUnits MaxAlignmentInChars =
1808  Context.toCharUnitsFromBits(D->getMaxAlignment());
1809  FieldAlign = std::max(FieldAlign, MaxAlignmentInChars);
1810  UnpackedFieldAlign = std::max(UnpackedFieldAlign, MaxAlignmentInChars);
1811 
1812  // The maximum field alignment overrides the aligned attribute.
1813  if (!MaxFieldAlignment.isZero()) {
1814  FieldAlign = std::min(FieldAlign, MaxFieldAlignment);
1815  UnpackedFieldAlign = std::min(UnpackedFieldAlign, MaxFieldAlignment);
1816  }
1817 
1818  // Round up the current record size to the field's alignment boundary.
1819  FieldOffset = FieldOffset.alignTo(FieldAlign);
1820  UnpackedFieldOffset = UnpackedFieldOffset.alignTo(UnpackedFieldAlign);
1821 
1822  if (UseExternalLayout) {
1823  FieldOffset = Context.toCharUnitsFromBits(
1824  updateExternalFieldOffset(D, Context.toBits(FieldOffset)));
1825 
1826  if (!IsUnion && EmptySubobjects) {
1827  // Record the fact that we're placing a field at this offset.
1828  bool Allowed = EmptySubobjects->CanPlaceFieldAtOffset(D, FieldOffset);
1829  (void)Allowed;
1830  assert(Allowed && "Externally-placed field cannot be placed here");
1831  }
1832  } else {
1833  if (!IsUnion && EmptySubobjects) {
1834  // Check if we can place the field at this offset.
1835  while (!EmptySubobjects->CanPlaceFieldAtOffset(D, FieldOffset)) {
1836  // We couldn't place the field at the offset. Try again at a new offset.
1837  FieldOffset += FieldAlign;
1838  }
1839  }
1840  }
1841 
1842  // Place this field at the current location.
1843  FieldOffsets.push_back(Context.toBits(FieldOffset));
1844 
1845  if (!UseExternalLayout)
1846  CheckFieldPadding(Context.toBits(FieldOffset), UnpaddedFieldOffset,
1847  Context.toBits(UnpackedFieldOffset),
1848  Context.toBits(UnpackedFieldAlign), FieldPacked, D);
1849 
1850  if (InsertExtraPadding) {
1851  CharUnits ASanAlignment = CharUnits::fromQuantity(8);
1852  CharUnits ExtraSizeForAsan = ASanAlignment;
1853  if (FieldSize % ASanAlignment)
1854  ExtraSizeForAsan +=
1855  ASanAlignment - CharUnits::fromQuantity(FieldSize % ASanAlignment);
1856  FieldSize += ExtraSizeForAsan;
1857  }
1858 
1859  // Reserve space for this field.
1860  uint64_t FieldSizeInBits = Context.toBits(FieldSize);
1861  if (IsUnion)
1862  setDataSize(std::max(getDataSizeInBits(), FieldSizeInBits));
1863  else
1864  setDataSize(FieldOffset + FieldSize);
1865 
1866  // Update the size.
1867  setSize(std::max(getSizeInBits(), getDataSizeInBits()));
1868 
1869  // Remember max struct/class alignment.
1870  UnadjustedAlignment = std::max(UnadjustedAlignment, FieldAlign);
1871  UpdateAlignment(FieldAlign, UnpackedFieldAlign);
1872 }
1873 
1874 void ItaniumRecordLayoutBuilder::FinishLayout(const NamedDecl *D) {
1875  // In C++, records cannot be of size 0.
1876  if (Context.getLangOpts().CPlusPlus && getSizeInBits() == 0) {
1877  if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D)) {
1878  // Compatibility with gcc requires a class (pod or non-pod)
1879  // which is not empty but of size 0; such as having fields of
1880  // array of zero-length, remains of Size 0
1881  if (RD->isEmpty())
1882  setSize(CharUnits::One());
1883  }
1884  else
1885  setSize(CharUnits::One());
1886  }
1887 
1888  // Finally, round the size of the record up to the alignment of the
1889  // record itself.
1890  uint64_t UnpaddedSize = getSizeInBits() - UnfilledBitsInLastUnit;
1891  uint64_t UnpackedSizeInBits =
1892  llvm::alignTo(getSizeInBits(), Context.toBits(UnpackedAlignment));
1893  uint64_t RoundedSize =
1894  llvm::alignTo(getSizeInBits(), Context.toBits(Alignment));
1895 
1896  if (UseExternalLayout) {
1897  // If we're inferring alignment, and the external size is smaller than
1898  // our size after we've rounded up to alignment, conservatively set the
1899  // alignment to 1.
1900  if (InferAlignment && External.Size < RoundedSize) {
1901  Alignment = CharUnits::One();
1902  InferAlignment = false;
1903  }
1904  setSize(External.Size);
1905  return;
1906  }
1907 
1908  // Set the size to the final size.
1909  setSize(RoundedSize);
1910 
1911  unsigned CharBitNum = Context.getTargetInfo().getCharWidth();
1912  if (const RecordDecl *RD = dyn_cast<RecordDecl>(D)) {
1913  // Warn if padding was introduced to the struct/class/union.
1914  if (getSizeInBits() > UnpaddedSize) {
1915  unsigned PadSize = getSizeInBits() - UnpaddedSize;
1916  bool InBits = true;
1917  if (PadSize % CharBitNum == 0) {
1918  PadSize = PadSize / CharBitNum;
1919  InBits = false;
1920  }
1921  Diag(RD->getLocation(), diag::warn_padded_struct_size)
1922  << Context.getTypeDeclType(RD)
1923  << PadSize
1924  << (InBits ? 1 : 0); // (byte|bit)
1925  }
1926 
1927  // Warn if we packed it unnecessarily, when the unpacked alignment is not
1928  // greater than the one after packing, the size in bits doesn't change and
1929  // the offset of each field is identical.
1930  if (Packed && UnpackedAlignment <= Alignment &&
1931  UnpackedSizeInBits == getSizeInBits() && !HasPackedField)
1932  Diag(D->getLocation(), diag::warn_unnecessary_packed)
1933  << Context.getTypeDeclType(RD);
1934  }
1935 }
1936 
1937 void ItaniumRecordLayoutBuilder::UpdateAlignment(
1938  CharUnits NewAlignment, CharUnits UnpackedNewAlignment) {
1939  // The alignment is not modified when using 'mac68k' alignment or when
1940  // we have an externally-supplied layout that also provides overall alignment.
1941  if (IsMac68kAlign || (UseExternalLayout && !InferAlignment))
1942  return;
1943 
1944  if (NewAlignment > Alignment) {
1945  assert(llvm::isPowerOf2_64(NewAlignment.getQuantity()) &&
1946  "Alignment not a power of 2");
1947  Alignment = NewAlignment;
1948  }
1949 
1950  if (UnpackedNewAlignment > UnpackedAlignment) {
1951  assert(llvm::isPowerOf2_64(UnpackedNewAlignment.getQuantity()) &&
1952  "Alignment not a power of 2");
1953  UnpackedAlignment = UnpackedNewAlignment;
1954  }
1955 }
1956 
1957 uint64_t
1958 ItaniumRecordLayoutBuilder::updateExternalFieldOffset(const FieldDecl *Field,
1959  uint64_t ComputedOffset) {
1960  uint64_t ExternalFieldOffset = External.getExternalFieldOffset(Field);
1961 
1962  if (InferAlignment && ExternalFieldOffset < ComputedOffset) {
1963  // The externally-supplied field offset is before the field offset we
1964  // computed. Assume that the structure is packed.
1965  Alignment = CharUnits::One();
1966  InferAlignment = false;
1967  }
1968 
1969  // Use the externally-supplied field offset.
1970  return ExternalFieldOffset;
1971 }
1972 
1973 /// Get diagnostic %select index for tag kind for
1974 /// field padding diagnostic message.
1975 /// WARNING: Indexes apply to particular diagnostics only!
1976 ///
1977 /// \returns diagnostic %select index.
1979  switch (Tag) {
1980  case TTK_Struct: return 0;
1981  case TTK_Interface: return 1;
1982  case TTK_Class: return 2;
1983  default: llvm_unreachable("Invalid tag kind for field padding diagnostic!");
1984  }
1985 }
1986 
1987 void ItaniumRecordLayoutBuilder::CheckFieldPadding(
1988  uint64_t Offset, uint64_t UnpaddedOffset, uint64_t UnpackedOffset,
1989  unsigned UnpackedAlign, bool isPacked, const FieldDecl *D) {
1990  // We let objc ivars without warning, objc interfaces generally are not used
1991  // for padding tricks.
1992  if (isa<ObjCIvarDecl>(D))
1993  return;
1994 
1995  // Don't warn about structs created without a SourceLocation. This can
1996  // be done by clients of the AST, such as codegen.
1997  if (D->getLocation().isInvalid())
1998  return;
1999 
2000  unsigned CharBitNum = Context.getTargetInfo().getCharWidth();
2001 
2002  // Warn if padding was introduced to the struct/class.
2003  if (!IsUnion && Offset > UnpaddedOffset) {
2004  unsigned PadSize = Offset - UnpaddedOffset;
2005  bool InBits = true;
2006  if (PadSize % CharBitNum == 0) {
2007  PadSize = PadSize / CharBitNum;
2008  InBits = false;
2009  }
2010  if (D->getIdentifier())
2011  Diag(D->getLocation(), diag::warn_padded_struct_field)
2013  << Context.getTypeDeclType(D->getParent())
2014  << PadSize
2015  << (InBits ? 1 : 0) // (byte|bit)
2016  << D->getIdentifier();
2017  else
2018  Diag(D->getLocation(), diag::warn_padded_struct_anon_field)
2020  << Context.getTypeDeclType(D->getParent())
2021  << PadSize
2022  << (InBits ? 1 : 0); // (byte|bit)
2023  }
2024  if (isPacked && Offset != UnpackedOffset) {
2025  HasPackedField = true;
2026  }
2027 }
2028 
2030  const CXXRecordDecl *RD) {
2031  // If a class isn't polymorphic it doesn't have a key function.
2032  if (!RD->isPolymorphic())
2033  return nullptr;
2034 
2035  // A class that is not externally visible doesn't have a key function. (Or
2036  // at least, there's no point to assigning a key function to such a class;
2037  // this doesn't affect the ABI.)
2038  if (!RD->isExternallyVisible())
2039  return nullptr;
2040 
2041  // Template instantiations don't have key functions per Itanium C++ ABI 5.2.6.
2042  // Same behavior as GCC.
2044  if (TSK == TSK_ImplicitInstantiation ||
2047  return nullptr;
2048 
2049  bool allowInlineFunctions =
2051 
2052  for (const CXXMethodDecl *MD : RD->methods()) {
2053  if (!MD->isVirtual())
2054  continue;
2055 
2056  if (MD->isPure())
2057  continue;
2058 
2059  // Ignore implicit member functions, they are always marked as inline, but
2060  // they don't have a body until they're defined.
2061  if (MD->isImplicit())
2062  continue;
2063 
2064  if (MD->isInlineSpecified())
2065  continue;
2066 
2067  if (MD->hasInlineBody())
2068  continue;
2069 
2070  // Ignore inline deleted or defaulted functions.
2071  if (!MD->isUserProvided())
2072  continue;
2073 
2074  // In certain ABIs, ignore functions with out-of-line inline definitions.
2075  if (!allowInlineFunctions) {
2076  const FunctionDecl *Def;
2077  if (MD->hasBody(Def) && Def->isInlineSpecified())
2078  continue;
2079  }
2080 
2081  if (Context.getLangOpts().CUDA) {
2082  // While compiler may see key method in this TU, during CUDA
2083  // compilation we should ignore methods that are not accessible
2084  // on this side of compilation.
2085  if (Context.getLangOpts().CUDAIsDevice) {
2086  // In device mode ignore methods without __device__ attribute.
2087  if (!MD->hasAttr<CUDADeviceAttr>())
2088  continue;
2089  } else {
2090  // In host mode ignore __device__-only methods.
2091  if (!MD->hasAttr<CUDAHostAttr>() && MD->hasAttr<CUDADeviceAttr>())
2092  continue;
2093  }
2094  }
2095 
2096  // If the key function is dllimport but the class isn't, then the class has
2097  // no key function. The DLL that exports the key function won't export the
2098  // vtable in this case.
2099  if (MD->hasAttr<DLLImportAttr>() && !RD->hasAttr<DLLImportAttr>())
2100  return nullptr;
2101 
2102  // We found it.
2103  return MD;
2104  }
2105 
2106  return nullptr;
2107 }
2108 
2110  unsigned DiagID) {
2111  return Context.getDiagnostics().Report(Loc, DiagID);
2112 }
2113 
2114 /// Does the target C++ ABI require us to skip over the tail-padding
2115 /// of the given class (considering it as a base class) when allocating
2116 /// objects?
2117 static bool mustSkipTailPadding(TargetCXXABI ABI, const CXXRecordDecl *RD) {
2118  switch (ABI.getTailPaddingUseRules()) {
2120  return false;
2121 
2123  // FIXME: To the extent that this is meant to cover the Itanium ABI
2124  // rules, we should implement the restrictions about over-sized
2125  // bitfields:
2126  //
2127  // http://itanium-cxx-abi.github.io/cxx-abi/abi.html#POD :
2128  // In general, a type is considered a POD for the purposes of
2129  // layout if it is a POD type (in the sense of ISO C++
2130  // [basic.types]). However, a POD-struct or POD-union (in the
2131  // sense of ISO C++ [class]) with a bitfield member whose
2132  // declared width is wider than the declared type of the
2133  // bitfield is not a POD for the purpose of layout. Similarly,
2134  // an array type is not a POD for the purpose of layout if the
2135  // element type of the array is not a POD for the purpose of
2136  // layout.
2137  //
2138  // Where references to the ISO C++ are made in this paragraph,
2139  // the Technical Corrigendum 1 version of the standard is
2140  // intended.
2141  return RD->isPOD();
2142 
2144  // This is equivalent to RD->getTypeForDecl().isCXX11PODType(),
2145  // but with a lot of abstraction penalty stripped off. This does
2146  // assume that these properties are set correctly even in C++98
2147  // mode; fortunately, that is true because we want to assign
2148  // consistently semantics to the type-traits intrinsics (or at
2149  // least as many of them as possible).
2150  return RD->isTrivial() && RD->isCXX11StandardLayout();
2151  }
2152 
2153  llvm_unreachable("bad tail-padding use kind");
2154 }
2155 
2156 static bool isMsLayout(const ASTContext &Context) {
2157  return Context.getTargetInfo().getCXXABI().isMicrosoft();
2158 }
2159 
2160 // This section contains an implementation of struct layout that is, up to the
2161 // included tests, compatible with cl.exe (2013). The layout produced is
2162 // significantly different than those produced by the Itanium ABI. Here we note
2163 // the most important differences.
2164 //
2165 // * The alignment of bitfields in unions is ignored when computing the
2166 // alignment of the union.
2167 // * The existence of zero-width bitfield that occurs after anything other than
2168 // a non-zero length bitfield is ignored.
2169 // * There is no explicit primary base for the purposes of layout. All bases
2170 // with vfptrs are laid out first, followed by all bases without vfptrs.
2171 // * The Itanium equivalent vtable pointers are split into a vfptr (virtual
2172 // function pointer) and a vbptr (virtual base pointer). They can each be
2173 // shared with a, non-virtual bases. These bases need not be the same. vfptrs
2174 // always occur at offset 0. vbptrs can occur at an arbitrary offset and are
2175 // placed after the lexicographically last non-virtual base. This placement
2176 // is always before fields but can be in the middle of the non-virtual bases
2177 // due to the two-pass layout scheme for non-virtual-bases.
2178 // * Virtual bases sometimes require a 'vtordisp' field that is laid out before
2179 // the virtual base and is used in conjunction with virtual overrides during
2180 // construction and destruction. This is always a 4 byte value and is used as
2181 // an alternative to constructor vtables.
2182 // * vtordisps are allocated in a block of memory with size and alignment equal
2183 // to the alignment of the completed structure (before applying __declspec(
2184 // align())). The vtordisp always occur at the end of the allocation block,
2185 // immediately prior to the virtual base.
2186 // * vfptrs are injected after all bases and fields have been laid out. In
2187 // order to guarantee proper alignment of all fields, the vfptr injection
2188 // pushes all bases and fields back by the alignment imposed by those bases
2189 // and fields. This can potentially add a significant amount of padding.
2190 // vfptrs are always injected at offset 0.
2191 // * vbptrs are injected after all bases and fields have been laid out. In
2192 // order to guarantee proper alignment of all fields, the vfptr injection
2193 // pushes all bases and fields back by the alignment imposed by those bases
2194 // and fields. This can potentially add a significant amount of padding.
2195 // vbptrs are injected immediately after the last non-virtual base as
2196 // lexicographically ordered in the code. If this site isn't pointer aligned
2197 // the vbptr is placed at the next properly aligned location. Enough padding
2198 // is added to guarantee a fit.
2199 // * The last zero sized non-virtual base can be placed at the end of the
2200 // struct (potentially aliasing another object), or may alias with the first
2201 // field, even if they are of the same type.
2202 // * The last zero size virtual base may be placed at the end of the struct
2203 // potentially aliasing another object.
2204 // * The ABI attempts to avoid aliasing of zero sized bases by adding padding
2205 // between bases or vbases with specific properties. The criteria for
2206 // additional padding between two bases is that the first base is zero sized
2207 // or ends with a zero sized subobject and the second base is zero sized or
2208 // trails with a zero sized base or field (sharing of vfptrs can reorder the
2209 // layout of the so the leading base is not always the first one declared).
2210 // This rule does take into account fields that are not records, so padding
2211 // will occur even if the last field is, e.g. an int. The padding added for
2212 // bases is 1 byte. The padding added between vbases depends on the alignment
2213 // of the object but is at least 4 bytes (in both 32 and 64 bit modes).
2214 // * There is no concept of non-virtual alignment, non-virtual alignment and
2215 // alignment are always identical.
2216 // * There is a distinction between alignment and required alignment.
2217 // __declspec(align) changes the required alignment of a struct. This
2218 // alignment is _always_ obeyed, even in the presence of #pragma pack. A
2219 // record inherits required alignment from all of its fields and bases.
2220 // * __declspec(align) on bitfields has the effect of changing the bitfield's
2221 // alignment instead of its required alignment. This is the only known way
2222 // to make the alignment of a struct bigger than 8. Interestingly enough
2223 // this alignment is also immune to the effects of #pragma pack and can be
2224 // used to create structures with large alignment under #pragma pack.
2225 // However, because it does not impact required alignment, such a structure,
2226 // when used as a field or base, will not be aligned if #pragma pack is
2227 // still active at the time of use.
2228 //
2229 // Known incompatibilities:
2230 // * all: #pragma pack between fields in a record
2231 // * 2010 and back: If the last field in a record is a bitfield, every object
2232 // laid out after the record will have extra padding inserted before it. The
2233 // extra padding will have size equal to the size of the storage class of the
2234 // bitfield. 0 sized bitfields don't exhibit this behavior and the extra
2235 // padding can be avoided by adding a 0 sized bitfield after the non-zero-
2236 // sized bitfield.
2237 // * 2012 and back: In 64-bit mode, if the alignment of a record is 16 or
2238 // greater due to __declspec(align()) then a second layout phase occurs after
2239 // The locations of the vf and vb pointers are known. This layout phase
2240 // suffers from the "last field is a bitfield" bug in 2010 and results in
2241 // _every_ field getting padding put in front of it, potentially including the
2242 // vfptr, leaving the vfprt at a non-zero location which results in a fault if
2243 // anything tries to read the vftbl. The second layout phase also treats
2244 // bitfields as separate entities and gives them each storage rather than
2245 // packing them. Additionally, because this phase appears to perform a
2246 // (an unstable) sort on the members before laying them out and because merged
2247 // bitfields have the same address, the bitfields end up in whatever order
2248 // the sort left them in, a behavior we could never hope to replicate.
2249 
2250 namespace {
2251 struct MicrosoftRecordLayoutBuilder {
2252  struct ElementInfo {
2253  CharUnits Size;
2254  CharUnits Alignment;
2255  };
2256  typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsetsMapTy;
2257  MicrosoftRecordLayoutBuilder(const ASTContext &Context) : Context(Context) {}
2258 private:
2259  MicrosoftRecordLayoutBuilder(const MicrosoftRecordLayoutBuilder &) = delete;
2260  void operator=(const MicrosoftRecordLayoutBuilder &) = delete;
2261 public:
2262  void layout(const RecordDecl *RD);
2263  void cxxLayout(const CXXRecordDecl *RD);
2264  /// Initializes size and alignment and honors some flags.
2265  void initializeLayout(const RecordDecl *RD);
2266  /// Initialized C++ layout, compute alignment and virtual alignment and
2267  /// existence of vfptrs and vbptrs. Alignment is needed before the vfptr is
2268  /// laid out.
2269  void initializeCXXLayout(const CXXRecordDecl *RD);
2270  void layoutNonVirtualBases(const CXXRecordDecl *RD);
2271  void layoutNonVirtualBase(const CXXRecordDecl *RD,
2272  const CXXRecordDecl *BaseDecl,
2273  const ASTRecordLayout &BaseLayout,
2274  const ASTRecordLayout *&PreviousBaseLayout);
2275  void injectVFPtr(const CXXRecordDecl *RD);
2276  void injectVBPtr(const CXXRecordDecl *RD);
2277  /// Lays out the fields of the record. Also rounds size up to
2278  /// alignment.
2279  void layoutFields(const RecordDecl *RD);
2280  void layoutField(const FieldDecl *FD);
2281  void layoutBitField(const FieldDecl *FD);
2282  /// Lays out a single zero-width bit-field in the record and handles
2283  /// special cases associated with zero-width bit-fields.
2284  void layoutZeroWidthBitField(const FieldDecl *FD);
2285  void layoutVirtualBases(const CXXRecordDecl *RD);
2286  void finalizeLayout(const RecordDecl *RD);
2287  /// Gets the size and alignment of a base taking pragma pack and
2288  /// __declspec(align) into account.
2289  ElementInfo getAdjustedElementInfo(const ASTRecordLayout &Layout);
2290  /// Gets the size and alignment of a field taking pragma pack and
2291  /// __declspec(align) into account. It also updates RequiredAlignment as a
2292  /// side effect because it is most convenient to do so here.
2293  ElementInfo getAdjustedElementInfo(const FieldDecl *FD);
2294  /// Places a field at an offset in CharUnits.
2295  void placeFieldAtOffset(CharUnits FieldOffset) {
2296  FieldOffsets.push_back(Context.toBits(FieldOffset));
2297  }
2298  /// Places a bitfield at a bit offset.
2299  void placeFieldAtBitOffset(uint64_t FieldOffset) {
2300  FieldOffsets.push_back(FieldOffset);
2301  }
2302  /// Compute the set of virtual bases for which vtordisps are required.
2303  void computeVtorDispSet(
2304  llvm::SmallPtrSetImpl<const CXXRecordDecl *> &HasVtorDispSet,
2305  const CXXRecordDecl *RD) const;
2306  const ASTContext &Context;
2307  /// The size of the record being laid out.
2308  CharUnits Size;
2309  /// The non-virtual size of the record layout.
2310  CharUnits NonVirtualSize;
2311  /// The data size of the record layout.
2312  CharUnits DataSize;
2313  /// The current alignment of the record layout.
2314  CharUnits Alignment;
2315  /// The maximum allowed field alignment. This is set by #pragma pack.
2316  CharUnits MaxFieldAlignment;
2317  /// The alignment that this record must obey. This is imposed by
2318  /// __declspec(align()) on the record itself or one of its fields or bases.
2319  CharUnits RequiredAlignment;
2320  /// The size of the allocation of the currently active bitfield.
2321  /// This value isn't meaningful unless LastFieldIsNonZeroWidthBitfield
2322  /// is true.
2323  CharUnits CurrentBitfieldSize;
2324  /// Offset to the virtual base table pointer (if one exists).
2325  CharUnits VBPtrOffset;
2326  /// Minimum record size possible.
2327  CharUnits MinEmptyStructSize;
2328  /// The size and alignment info of a pointer.
2329  ElementInfo PointerInfo;
2330  /// The primary base class (if one exists).
2331  const CXXRecordDecl *PrimaryBase;
2332  /// The class we share our vb-pointer with.
2333  const CXXRecordDecl *SharedVBPtrBase;
2334  /// The collection of field offsets.
2335  SmallVector<uint64_t, 16> FieldOffsets;
2336  /// Base classes and their offsets in the record.
2337  BaseOffsetsMapTy Bases;
2338  /// virtual base classes and their offsets in the record.
2340  /// The number of remaining bits in our last bitfield allocation.
2341  /// This value isn't meaningful unless LastFieldIsNonZeroWidthBitfield is
2342  /// true.
2343  unsigned RemainingBitsInField;
2344  bool IsUnion : 1;
2345  /// True if the last field laid out was a bitfield and was not 0
2346  /// width.
2347  bool LastFieldIsNonZeroWidthBitfield : 1;
2348  /// True if the class has its own vftable pointer.
2349  bool HasOwnVFPtr : 1;
2350  /// True if the class has a vbtable pointer.
2351  bool HasVBPtr : 1;
2352  /// True if the last sub-object within the type is zero sized or the
2353  /// object itself is zero sized. This *does not* count members that are not
2354  /// records. Only used for MS-ABI.
2355  bool EndsWithZeroSizedObject : 1;
2356  /// True if this class is zero sized or first base is zero sized or
2357  /// has this property. Only used for MS-ABI.
2358  bool LeadsWithZeroSizedBase : 1;
2359 
2360  /// True if the external AST source provided a layout for this record.
2361  bool UseExternalLayout : 1;
2362 
2363  /// The layout provided by the external AST source. Only active if
2364  /// UseExternalLayout is true.
2365  ExternalLayout External;
2366 };
2367 } // namespace
2368 
2369 MicrosoftRecordLayoutBuilder::ElementInfo
2370 MicrosoftRecordLayoutBuilder::getAdjustedElementInfo(
2371  const ASTRecordLayout &Layout) {
2372  ElementInfo Info;
2373  Info.Alignment = Layout.getAlignment();
2374  // Respect pragma pack.
2375  if (!MaxFieldAlignment.isZero())
2376  Info.Alignment = std::min(Info.Alignment, MaxFieldAlignment);
2377  // Track zero-sized subobjects here where it's already available.
2378  EndsWithZeroSizedObject = Layout.endsWithZeroSizedObject();
2379  // Respect required alignment, this is necessary because we may have adjusted
2380  // the alignment in the case of pragam pack. Note that the required alignment
2381  // doesn't actually apply to the struct alignment at this point.
2382  Alignment = std::max(Alignment, Info.Alignment);
2383  RequiredAlignment = std::max(RequiredAlignment, Layout.getRequiredAlignment());
2384  Info.Alignment = std::max(Info.Alignment, Layout.getRequiredAlignment());
2385  Info.Size = Layout.getNonVirtualSize();
2386  return Info;
2387 }
2388 
2389 MicrosoftRecordLayoutBuilder::ElementInfo
2390 MicrosoftRecordLayoutBuilder::getAdjustedElementInfo(
2391  const FieldDecl *FD) {
2392  // Get the alignment of the field type's natural alignment, ignore any
2393  // alignment attributes.
2394  ElementInfo Info;
2395  std::tie(Info.Size, Info.Alignment) =
2397  // Respect align attributes on the field.
2398  CharUnits FieldRequiredAlignment =
2399  Context.toCharUnitsFromBits(FD->getMaxAlignment());
2400  // Respect align attributes on the type.
2401  if (Context.isAlignmentRequired(FD->getType()))
2402  FieldRequiredAlignment = std::max(
2403  Context.getTypeAlignInChars(FD->getType()), FieldRequiredAlignment);
2404  // Respect attributes applied to subobjects of the field.
2405  if (FD->isBitField())
2406  // For some reason __declspec align impacts alignment rather than required
2407  // alignment when it is applied to bitfields.
2408  Info.Alignment = std::max(Info.Alignment, FieldRequiredAlignment);
2409  else {
2410  if (auto RT =
2412  auto const &Layout = Context.getASTRecordLayout(RT->getDecl());
2413  EndsWithZeroSizedObject = Layout.endsWithZeroSizedObject();
2414  FieldRequiredAlignment = std::max(FieldRequiredAlignment,
2415  Layout.getRequiredAlignment());
2416  }
2417  // Capture required alignment as a side-effect.
2418  RequiredAlignment = std::max(RequiredAlignment, FieldRequiredAlignment);
2419  }
2420  // Respect pragma pack, attribute pack and declspec align
2421  if (!MaxFieldAlignment.isZero())
2422  Info.Alignment = std::min(Info.Alignment, MaxFieldAlignment);
2423  if (FD->hasAttr<PackedAttr>())
2424  Info.Alignment = CharUnits::One();
2425  Info.Alignment = std::max(Info.Alignment, FieldRequiredAlignment);
2426  return Info;
2427 }
2428 
2429 void MicrosoftRecordLayoutBuilder::layout(const RecordDecl *RD) {
2430  // For C record layout, zero-sized records always have size 4.
2431  MinEmptyStructSize = CharUnits::fromQuantity(4);
2432  initializeLayout(RD);
2433  layoutFields(RD);
2434  DataSize = Size = Size.alignTo(Alignment);
2435  RequiredAlignment = std::max(
2436  RequiredAlignment, Context.toCharUnitsFromBits(RD->getMaxAlignment()));
2437  finalizeLayout(RD);
2438 }
2439 
2440 void MicrosoftRecordLayoutBuilder::cxxLayout(const CXXRecordDecl *RD) {
2441  // The C++ standard says that empty structs have size 1.
2442  MinEmptyStructSize = CharUnits::One();
2443  initializeLayout(RD);
2444  initializeCXXLayout(RD);
2445  layoutNonVirtualBases(RD);
2446  layoutFields(RD);
2447  injectVBPtr(RD);
2448  injectVFPtr(RD);
2449  if (HasOwnVFPtr || (HasVBPtr && !SharedVBPtrBase))
2450  Alignment = std::max(Alignment, PointerInfo.Alignment);
2451  auto RoundingAlignment = Alignment;
2452  if (!MaxFieldAlignment.isZero())
2453  RoundingAlignment = std::min(RoundingAlignment, MaxFieldAlignment);
2454  if (!UseExternalLayout)
2455  Size = Size.alignTo(RoundingAlignment);
2456  NonVirtualSize = Size;
2457  RequiredAlignment = std::max(
2458  RequiredAlignment, Context.toCharUnitsFromBits(RD->getMaxAlignment()));
2459  layoutVirtualBases(RD);
2460  finalizeLayout(RD);
2461 }
2462 
2463 void MicrosoftRecordLayoutBuilder::initializeLayout(const RecordDecl *RD) {
2464  IsUnion = RD->isUnion();
2465  Size = CharUnits::Zero();
2466  Alignment = CharUnits::One();
2467  // In 64-bit mode we always perform an alignment step after laying out vbases.
2468  // In 32-bit mode we do not. The check to see if we need to perform alignment
2469  // checks the RequiredAlignment field and performs alignment if it isn't 0.
2470  RequiredAlignment = Context.getTargetInfo().getTriple().isArch64Bit()
2471  ? CharUnits::One()
2472  : CharUnits::Zero();
2473  // Compute the maximum field alignment.
2474  MaxFieldAlignment = CharUnits::Zero();
2475  // Honor the default struct packing maximum alignment flag.
2476  if (unsigned DefaultMaxFieldAlignment = Context.getLangOpts().PackStruct)
2477  MaxFieldAlignment = CharUnits::fromQuantity(DefaultMaxFieldAlignment);
2478  // Honor the packing attribute. The MS-ABI ignores pragma pack if its larger
2479  // than the pointer size.
2480  if (const MaxFieldAlignmentAttr *MFAA = RD->getAttr<MaxFieldAlignmentAttr>()){
2481  unsigned PackedAlignment = MFAA->getAlignment();
2482  if (PackedAlignment <= Context.getTargetInfo().getPointerWidth(0))
2483  MaxFieldAlignment = Context.toCharUnitsFromBits(PackedAlignment);
2484  }
2485  // Packed attribute forces max field alignment to be 1.
2486  if (RD->hasAttr<PackedAttr>())
2487  MaxFieldAlignment = CharUnits::One();
2488 
2489  // Try to respect the external layout if present.
2490  UseExternalLayout = false;
2491  if (ExternalASTSource *Source = Context.getExternalSource())
2492  UseExternalLayout = Source->layoutRecordType(
2493  RD, External.Size, External.Align, External.FieldOffsets,
2494  External.BaseOffsets, External.VirtualBaseOffsets);
2495 }
2496 
2497 void
2498 MicrosoftRecordLayoutBuilder::initializeCXXLayout(const CXXRecordDecl *RD) {
2499  EndsWithZeroSizedObject = false;
2500  LeadsWithZeroSizedBase = false;
2501  HasOwnVFPtr = false;
2502  HasVBPtr = false;
2503  PrimaryBase = nullptr;
2504  SharedVBPtrBase = nullptr;
2505  // Calculate pointer size and alignment. These are used for vfptr and vbprt
2506  // injection.
2507  PointerInfo.Size =
2508  Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
2509  PointerInfo.Alignment =
2510  Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerAlign(0));
2511  // Respect pragma pack.
2512  if (!MaxFieldAlignment.isZero())
2513  PointerInfo.Alignment = std::min(PointerInfo.Alignment, MaxFieldAlignment);
2514 }
2515 
2516 void
2517 MicrosoftRecordLayoutBuilder::layoutNonVirtualBases(const CXXRecordDecl *RD) {
2518  // The MS-ABI lays out all bases that contain leading vfptrs before it lays
2519  // out any bases that do not contain vfptrs. We implement this as two passes
2520  // over the bases. This approach guarantees that the primary base is laid out
2521  // first. We use these passes to calculate some additional aggregated
2522  // information about the bases, such as required alignment and the presence of
2523  // zero sized members.
2524  const ASTRecordLayout *PreviousBaseLayout = nullptr;
2525  // Iterate through the bases and lay out the non-virtual ones.
2526  for (const CXXBaseSpecifier &Base : RD->bases()) {
2527  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2528  const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2529  // Mark and skip virtual bases.
2530  if (Base.isVirtual()) {
2531  HasVBPtr = true;
2532  continue;
2533  }
2534  // Check for a base to share a VBPtr with.
2535  if (!SharedVBPtrBase && BaseLayout.hasVBPtr()) {
2536  SharedVBPtrBase = BaseDecl;
2537  HasVBPtr = true;
2538  }
2539  // Only lay out bases with extendable VFPtrs on the first pass.
2540  if (!BaseLayout.hasExtendableVFPtr())
2541  continue;
2542  // If we don't have a primary base, this one qualifies.
2543  if (!PrimaryBase) {
2544  PrimaryBase = BaseDecl;
2545  LeadsWithZeroSizedBase = BaseLayout.leadsWithZeroSizedBase();
2546  }
2547  // Lay out the base.
2548  layoutNonVirtualBase(RD, BaseDecl, BaseLayout, PreviousBaseLayout);
2549  }
2550  // Figure out if we need a fresh VFPtr for this class.
2551  if (!PrimaryBase && RD->isDynamicClass())
2553  e = RD->method_end();
2554  !HasOwnVFPtr && i != e; ++i)
2555  HasOwnVFPtr = i->isVirtual() && i->size_overridden_methods() == 0;
2556  // If we don't have a primary base then we have a leading object that could
2557  // itself lead with a zero-sized object, something we track.
2558  bool CheckLeadingLayout = !PrimaryBase;
2559  // Iterate through the bases and lay out the non-virtual ones.
2560  for (const CXXBaseSpecifier &Base : RD->bases()) {
2561  if (Base.isVirtual())
2562  continue;
2563  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2564  const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2565  // Only lay out bases without extendable VFPtrs on the second pass.
2566  if (BaseLayout.hasExtendableVFPtr()) {
2567  VBPtrOffset = Bases[BaseDecl] + BaseLayout.getNonVirtualSize();
2568  continue;
2569  }
2570  // If this is the first layout, check to see if it leads with a zero sized
2571  // object. If it does, so do we.
2572  if (CheckLeadingLayout) {
2573  CheckLeadingLayout = false;
2574  LeadsWithZeroSizedBase = BaseLayout.leadsWithZeroSizedBase();
2575  }
2576  // Lay out the base.
2577  layoutNonVirtualBase(RD, BaseDecl, BaseLayout, PreviousBaseLayout);
2578  VBPtrOffset = Bases[BaseDecl] + BaseLayout.getNonVirtualSize();
2579  }
2580  // Set our VBPtroffset if we know it at this point.
2581  if (!HasVBPtr)
2582  VBPtrOffset = CharUnits::fromQuantity(-1);
2583  else if (SharedVBPtrBase) {
2584  const ASTRecordLayout &Layout = Context.getASTRecordLayout(SharedVBPtrBase);
2585  VBPtrOffset = Bases[SharedVBPtrBase] + Layout.getVBPtrOffset();
2586  }
2587 }
2588 
2589 static bool recordUsesEBO(const RecordDecl *RD) {
2590  if (!isa<CXXRecordDecl>(RD))
2591  return false;
2592  if (RD->hasAttr<EmptyBasesAttr>())
2593  return true;
2594  if (auto *LVA = RD->getAttr<LayoutVersionAttr>())
2595  // TODO: Double check with the next version of MSVC.
2596  if (LVA->getVersion() <= LangOptions::MSVC2015)
2597  return false;
2598  // TODO: Some later version of MSVC will change the default behavior of the
2599  // compiler to enable EBO by default. When this happens, we will need an
2600  // additional isCompatibleWithMSVC check.
2601  return false;
2602 }
2603 
2604 void MicrosoftRecordLayoutBuilder::layoutNonVirtualBase(
2605  const CXXRecordDecl *RD,
2606  const CXXRecordDecl *BaseDecl,
2607  const ASTRecordLayout &BaseLayout,
2608  const ASTRecordLayout *&PreviousBaseLayout) {
2609  // Insert padding between two bases if the left first one is zero sized or
2610  // contains a zero sized subobject and the right is zero sized or one leads
2611  // with a zero sized base.
2612  bool MDCUsesEBO = recordUsesEBO(RD);
2613  if (PreviousBaseLayout && PreviousBaseLayout->endsWithZeroSizedObject() &&
2614  BaseLayout.leadsWithZeroSizedBase() && !MDCUsesEBO)
2615  Size++;
2616  ElementInfo Info = getAdjustedElementInfo(BaseLayout);
2617  CharUnits BaseOffset;
2618 
2619  // Respect the external AST source base offset, if present.
2620  bool FoundBase = false;
2621  if (UseExternalLayout) {
2622  FoundBase = External.getExternalNVBaseOffset(BaseDecl, BaseOffset);
2623  if (FoundBase) {
2624  assert(BaseOffset >= Size && "base offset already allocated");
2625  Size = BaseOffset;
2626  }
2627  }
2628 
2629  if (!FoundBase) {
2630  if (MDCUsesEBO && BaseDecl->isEmpty()) {
2631  assert(BaseLayout.getNonVirtualSize() == CharUnits::Zero());
2632  BaseOffset = CharUnits::Zero();
2633  } else {
2634  // Otherwise, lay the base out at the end of the MDC.
2635  BaseOffset = Size = Size.alignTo(Info.Alignment);
2636  }
2637  }
2638  Bases.insert(std::make_pair(BaseDecl, BaseOffset));
2639  Size += BaseLayout.getNonVirtualSize();
2640  PreviousBaseLayout = &BaseLayout;
2641 }
2642 
2643 void MicrosoftRecordLayoutBuilder::layoutFields(const RecordDecl *RD) {
2644  LastFieldIsNonZeroWidthBitfield = false;
2645  for (const FieldDecl *Field : RD->fields())
2646  layoutField(Field);
2647 }
2648 
2649 void MicrosoftRecordLayoutBuilder::layoutField(const FieldDecl *FD) {
2650  if (FD->isBitField()) {
2651  layoutBitField(FD);
2652  return;
2653  }
2654  LastFieldIsNonZeroWidthBitfield = false;
2655  ElementInfo Info = getAdjustedElementInfo(FD);
2656  Alignment = std::max(Alignment, Info.Alignment);
2657  CharUnits FieldOffset;
2658  if (UseExternalLayout)
2659  FieldOffset =
2660  Context.toCharUnitsFromBits(External.getExternalFieldOffset(FD));
2661  else if (IsUnion)
2662  FieldOffset = CharUnits::Zero();
2663  else
2664  FieldOffset = Size.alignTo(Info.Alignment);
2665  placeFieldAtOffset(FieldOffset);
2666  Size = std::max(Size, FieldOffset + Info.Size);
2667 }
2668 
2669 void MicrosoftRecordLayoutBuilder::layoutBitField(const FieldDecl *FD) {
2670  unsigned Width = FD->getBitWidthValue(Context);
2671  if (Width == 0) {
2672  layoutZeroWidthBitField(FD);
2673  return;
2674  }
2675  ElementInfo Info = getAdjustedElementInfo(FD);
2676  // Clamp the bitfield to a containable size for the sake of being able
2677  // to lay them out. Sema will throw an error.
2678  if (Width > Context.toBits(Info.Size))
2679  Width = Context.toBits(Info.Size);
2680  // Check to see if this bitfield fits into an existing allocation. Note:
2681  // MSVC refuses to pack bitfields of formal types with different sizes
2682  // into the same allocation.
2683  if (!UseExternalLayout && !IsUnion && LastFieldIsNonZeroWidthBitfield &&
2684  CurrentBitfieldSize == Info.Size && Width <= RemainingBitsInField) {
2685  placeFieldAtBitOffset(Context.toBits(Size) - RemainingBitsInField);
2686  RemainingBitsInField -= Width;
2687  return;
2688  }
2689  LastFieldIsNonZeroWidthBitfield = true;
2690  CurrentBitfieldSize = Info.Size;
2691  if (UseExternalLayout) {
2692  auto FieldBitOffset = External.getExternalFieldOffset(FD);
2693  placeFieldAtBitOffset(FieldBitOffset);
2694  auto NewSize = Context.toCharUnitsFromBits(
2695  llvm::alignTo(FieldBitOffset + Width, Context.getCharWidth()));
2696  Size = std::max(Size, NewSize);
2697  Alignment = std::max(Alignment, Info.Alignment);
2698  } else if (IsUnion) {
2699  placeFieldAtOffset(CharUnits::Zero());
2700  Size = std::max(Size, Info.Size);
2701  // TODO: Add a Sema warning that MS ignores bitfield alignment in unions.
2702  } else {
2703  // Allocate a new block of memory and place the bitfield in it.
2704  CharUnits FieldOffset = Size.alignTo(Info.Alignment);
2705  placeFieldAtOffset(FieldOffset);
2706  Size = FieldOffset + Info.Size;
2707  Alignment = std::max(Alignment, Info.Alignment);
2708  RemainingBitsInField = Context.toBits(Info.Size) - Width;
2709  }
2710 }
2711 
2712 void
2713 MicrosoftRecordLayoutBuilder::layoutZeroWidthBitField(const FieldDecl *FD) {
2714  // Zero-width bitfields are ignored unless they follow a non-zero-width
2715  // bitfield.
2716  if (!LastFieldIsNonZeroWidthBitfield) {
2717  placeFieldAtOffset(IsUnion ? CharUnits::Zero() : Size);
2718  // TODO: Add a Sema warning that MS ignores alignment for zero
2719  // sized bitfields that occur after zero-size bitfields or non-bitfields.
2720  return;
2721  }
2722  LastFieldIsNonZeroWidthBitfield = false;
2723  ElementInfo Info = getAdjustedElementInfo(FD);
2724  if (IsUnion) {
2725  placeFieldAtOffset(CharUnits::Zero());
2726  Size = std::max(Size, Info.Size);
2727  // TODO: Add a Sema warning that MS ignores bitfield alignment in unions.
2728  } else {
2729  // Round up the current record size to the field's alignment boundary.
2730  CharUnits FieldOffset = Size.alignTo(Info.Alignment);
2731  placeFieldAtOffset(FieldOffset);
2732  Size = FieldOffset;
2733  Alignment = std::max(Alignment, Info.Alignment);
2734  }
2735 }
2736 
2737 void MicrosoftRecordLayoutBuilder::injectVBPtr(const CXXRecordDecl *RD) {
2738  if (!HasVBPtr || SharedVBPtrBase)
2739  return;
2740  // Inject the VBPointer at the injection site.
2741  CharUnits InjectionSite = VBPtrOffset;
2742  // But before we do, make sure it's properly aligned.
2743  VBPtrOffset = VBPtrOffset.alignTo(PointerInfo.Alignment);
2744  // Shift everything after the vbptr down, unless we're using an external
2745  // layout.
2746  if (UseExternalLayout)
2747  return;
2748  // Determine where the first field should be laid out after the vbptr.
2749  CharUnits FieldStart = VBPtrOffset + PointerInfo.Size;
2750  // Make sure that the amount we push the fields back by is a multiple of the
2751  // alignment.
2752  CharUnits Offset = (FieldStart - InjectionSite)
2753  .alignTo(std::max(RequiredAlignment, Alignment));
2754  Size += Offset;
2755  for (uint64_t &FieldOffset : FieldOffsets)
2756  FieldOffset += Context.toBits(Offset);
2757  for (BaseOffsetsMapTy::value_type &Base : Bases)
2758  if (Base.second >= InjectionSite)
2759  Base.second += Offset;
2760 }
2761 
2762 void MicrosoftRecordLayoutBuilder::injectVFPtr(const CXXRecordDecl *RD) {
2763  if (!HasOwnVFPtr)
2764  return;
2765  // Make sure that the amount we push the struct back by is a multiple of the
2766  // alignment.
2767  CharUnits Offset =
2768  PointerInfo.Size.alignTo(std::max(RequiredAlignment, Alignment));
2769  // Push back the vbptr, but increase the size of the object and push back
2770  // regular fields by the offset only if not using external record layout.
2771  if (HasVBPtr)
2772  VBPtrOffset += Offset;
2773 
2774  if (UseExternalLayout)
2775  return;
2776 
2777  Size += Offset;
2778 
2779  // If we're using an external layout, the fields offsets have already
2780  // accounted for this adjustment.
2781  for (uint64_t &FieldOffset : FieldOffsets)
2782  FieldOffset += Context.toBits(Offset);
2783  for (BaseOffsetsMapTy::value_type &Base : Bases)
2784  Base.second += Offset;
2785 }
2786 
2787 void MicrosoftRecordLayoutBuilder::layoutVirtualBases(const CXXRecordDecl *RD) {
2788  if (!HasVBPtr)
2789  return;
2790  // Vtordisps are always 4 bytes (even in 64-bit mode)
2791  CharUnits VtorDispSize = CharUnits::fromQuantity(4);
2792  CharUnits VtorDispAlignment = VtorDispSize;
2793  // vtordisps respect pragma pack.
2794  if (!MaxFieldAlignment.isZero())
2795  VtorDispAlignment = std::min(VtorDispAlignment, MaxFieldAlignment);
2796  // The alignment of the vtordisp is at least the required alignment of the
2797  // entire record. This requirement may be present to support vtordisp
2798  // injection.
2799  for (const CXXBaseSpecifier &VBase : RD->vbases()) {
2800  const CXXRecordDecl *BaseDecl = VBase.getType()->getAsCXXRecordDecl();
2801  const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2802  RequiredAlignment =
2803  std::max(RequiredAlignment, BaseLayout.getRequiredAlignment());
2804  }
2805  VtorDispAlignment = std::max(VtorDispAlignment, RequiredAlignment);
2806  // Compute the vtordisp set.
2807  llvm::SmallPtrSet<const CXXRecordDecl *, 2> HasVtorDispSet;
2808  computeVtorDispSet(HasVtorDispSet, RD);
2809  // Iterate through the virtual bases and lay them out.
2810  const ASTRecordLayout *PreviousBaseLayout = nullptr;
2811  for (const CXXBaseSpecifier &VBase : RD->vbases()) {
2812  const CXXRecordDecl *BaseDecl = VBase.getType()->getAsCXXRecordDecl();
2813  const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2814  bool HasVtordisp = HasVtorDispSet.count(BaseDecl) > 0;
2815  // Insert padding between two bases if the left first one is zero sized or
2816  // contains a zero sized subobject and the right is zero sized or one leads
2817  // with a zero sized base. The padding between virtual bases is 4
2818  // bytes (in both 32 and 64 bits modes) and always involves rounding up to
2819  // the required alignment, we don't know why.
2820  if ((PreviousBaseLayout && PreviousBaseLayout->endsWithZeroSizedObject() &&
2821  BaseLayout.leadsWithZeroSizedBase() && !recordUsesEBO(RD)) ||
2822  HasVtordisp) {
2823  Size = Size.alignTo(VtorDispAlignment) + VtorDispSize;
2824  Alignment = std::max(VtorDispAlignment, Alignment);
2825  }
2826  // Insert the virtual base.
2827  ElementInfo Info = getAdjustedElementInfo(BaseLayout);
2828  CharUnits BaseOffset;
2829 
2830  // Respect the external AST source base offset, if present.
2831  if (UseExternalLayout) {
2832  if (!External.getExternalVBaseOffset(BaseDecl, BaseOffset))
2833  BaseOffset = Size;
2834  } else
2835  BaseOffset = Size.alignTo(Info.Alignment);
2836 
2837  assert(BaseOffset >= Size && "base offset already allocated");
2838 
2839  VBases.insert(std::make_pair(BaseDecl,
2840  ASTRecordLayout::VBaseInfo(BaseOffset, HasVtordisp)));
2841  Size = BaseOffset + BaseLayout.getNonVirtualSize();
2842  PreviousBaseLayout = &BaseLayout;
2843  }
2844 }
2845 
2846 void MicrosoftRecordLayoutBuilder::finalizeLayout(const RecordDecl *RD) {
2847  // Respect required alignment. Note that in 32-bit mode Required alignment
2848  // may be 0 and cause size not to be updated.
2849  DataSize = Size;
2850  if (!RequiredAlignment.isZero()) {
2851  Alignment = std::max(Alignment, RequiredAlignment);
2852  auto RoundingAlignment = Alignment;
2853  if (!MaxFieldAlignment.isZero())
2854  RoundingAlignment = std::min(RoundingAlignment, MaxFieldAlignment);
2855  RoundingAlignment = std::max(RoundingAlignment, RequiredAlignment);
2856  Size = Size.alignTo(RoundingAlignment);
2857  }
2858  if (Size.isZero()) {
2859  if (!recordUsesEBO(RD) || !cast<CXXRecordDecl>(RD)->isEmpty()) {
2860  EndsWithZeroSizedObject = true;
2861  LeadsWithZeroSizedBase = true;
2862  }
2863  // Zero-sized structures have size equal to their alignment if a
2864  // __declspec(align) came into play.
2865  if (RequiredAlignment >= MinEmptyStructSize)
2866  Size = Alignment;
2867  else
2868  Size = MinEmptyStructSize;
2869  }
2870 
2871  if (UseExternalLayout) {
2872  Size = Context.toCharUnitsFromBits(External.Size);
2873  if (External.Align)
2874  Alignment = Context.toCharUnitsFromBits(External.Align);
2875  }
2876 }
2877 
2878 // Recursively walks the non-virtual bases of a class and determines if any of
2879 // them are in the bases with overridden methods set.
2880 static bool
2881 RequiresVtordisp(const llvm::SmallPtrSetImpl<const CXXRecordDecl *> &
2882  BasesWithOverriddenMethods,
2883  const CXXRecordDecl *RD) {
2884  if (BasesWithOverriddenMethods.count(RD))
2885  return true;
2886  // If any of a virtual bases non-virtual bases (recursively) requires a
2887  // vtordisp than so does this virtual base.
2888  for (const CXXBaseSpecifier &Base : RD->bases())
2889  if (!Base.isVirtual() &&
2890  RequiresVtordisp(BasesWithOverriddenMethods,
2891  Base.getType()->getAsCXXRecordDecl()))
2892  return true;
2893  return false;
2894 }
2895 
2896 void MicrosoftRecordLayoutBuilder::computeVtorDispSet(
2897  llvm::SmallPtrSetImpl<const CXXRecordDecl *> &HasVtordispSet,
2898  const CXXRecordDecl *RD) const {
2899  // /vd2 or #pragma vtordisp(2): Always use vtordisps for virtual bases with
2900  // vftables.
2901  if (RD->getMSVtorDispMode() == MSVtorDispAttr::ForVFTable) {
2902  for (const CXXBaseSpecifier &Base : RD->vbases()) {
2903  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2904  const ASTRecordLayout &Layout = Context.getASTRecordLayout(BaseDecl);
2905  if (Layout.hasExtendableVFPtr())
2906  HasVtordispSet.insert(BaseDecl);
2907  }
2908  return;
2909  }
2910 
2911  // If any of our bases need a vtordisp for this type, so do we. Check our
2912  // direct bases for vtordisp requirements.
2913  for (const CXXBaseSpecifier &Base : RD->bases()) {
2914  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2915  const ASTRecordLayout &Layout = Context.getASTRecordLayout(BaseDecl);
2916  for (const auto &bi : Layout.getVBaseOffsetsMap())
2917  if (bi.second.hasVtorDisp())
2918  HasVtordispSet.insert(bi.first);
2919  }
2920  // We don't introduce any additional vtordisps if either:
2921  // * A user declared constructor or destructor aren't declared.
2922  // * #pragma vtordisp(0) or the /vd0 flag are in use.
2923  if ((!RD->hasUserDeclaredConstructor() && !RD->hasUserDeclaredDestructor()) ||
2924  RD->getMSVtorDispMode() == MSVtorDispAttr::Never)
2925  return;
2926  // /vd1 or #pragma vtordisp(1): Try to guess based on whether we think it's
2927  // possible for a partially constructed object with virtual base overrides to
2928  // escape a non-trivial constructor.
2929  assert(RD->getMSVtorDispMode() == MSVtorDispAttr::ForVBaseOverride);
2930  // Compute a set of base classes which define methods we override. A virtual
2931  // base in this set will require a vtordisp. A virtual base that transitively
2932  // contains one of these bases as a non-virtual base will also require a
2933  // vtordisp.
2934  llvm::SmallPtrSet<const CXXMethodDecl *, 8> Work;
2935  llvm::SmallPtrSet<const CXXRecordDecl *, 2> BasesWithOverriddenMethods;
2936  // Seed the working set with our non-destructor, non-pure virtual methods.
2937  for (const CXXMethodDecl *MD : RD->methods())
2938  if (MD->isVirtual() && !isa<CXXDestructorDecl>(MD) && !MD->isPure())
2939  Work.insert(MD);
2940  while (!Work.empty()) {
2941  const CXXMethodDecl *MD = *Work.begin();
2942  auto MethodRange = MD->overridden_methods();
2943  // If a virtual method has no-overrides it lives in its parent's vtable.
2944  if (MethodRange.begin() == MethodRange.end())
2945  BasesWithOverriddenMethods.insert(MD->getParent());
2946  else
2947  Work.insert(MethodRange.begin(), MethodRange.end());
2948  // We've finished processing this element, remove it from the working set.
2949  Work.erase(MD);
2950  }
2951  // For each of our virtual bases, check if it is in the set of overridden
2952  // bases or if it transitively contains a non-virtual base that is.
2953  for (const CXXBaseSpecifier &Base : RD->vbases()) {
2954  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2955  if (!HasVtordispSet.count(BaseDecl) &&
2956  RequiresVtordisp(BasesWithOverriddenMethods, BaseDecl))
2957  HasVtordispSet.insert(BaseDecl);
2958  }
2959 }
2960 
2961 /// getASTRecordLayout - Get or compute information about the layout of the
2962 /// specified record (struct/union/class), which indicates its size and field
2963 /// position information.
2964 const ASTRecordLayout &
2966  // These asserts test different things. A record has a definition
2967  // as soon as we begin to parse the definition. That definition is
2968  // not a complete definition (which is what isDefinition() tests)
2969  // until we *finish* parsing the definition.
2970 
2971  if (D->hasExternalLexicalStorage() && !D->getDefinition())
2972  getExternalSource()->CompleteType(const_cast<RecordDecl*>(D));
2973 
2974  D = D->getDefinition();
2975  assert(D && "Cannot get layout of forward declarations!");
2976  assert(!D->isInvalidDecl() && "Cannot get layout of invalid decl!");
2977  assert(D->isCompleteDefinition() && "Cannot layout type before complete!");
2978 
2979  // Look up this layout, if already laid out, return what we have.
2980  // Note that we can't save a reference to the entry because this function
2981  // is recursive.
2982  const ASTRecordLayout *Entry = ASTRecordLayouts[D];
2983  if (Entry) return *Entry;
2984 
2985  const ASTRecordLayout *NewEntry = nullptr;
2986 
2987  if (isMsLayout(*this)) {
2988  MicrosoftRecordLayoutBuilder Builder(*this);
2989  if (const auto *RD = dyn_cast<CXXRecordDecl>(D)) {
2990  Builder.cxxLayout(RD);
2991  NewEntry = new (*this) ASTRecordLayout(
2992  *this, Builder.Size, Builder.Alignment, Builder.Alignment,
2993  Builder.RequiredAlignment,
2994  Builder.HasOwnVFPtr, Builder.HasOwnVFPtr || Builder.PrimaryBase,
2995  Builder.VBPtrOffset, Builder.DataSize, Builder.FieldOffsets,
2996  Builder.NonVirtualSize, Builder.Alignment, CharUnits::Zero(),
2997  Builder.PrimaryBase, false, Builder.SharedVBPtrBase,
2998  Builder.EndsWithZeroSizedObject, Builder.LeadsWithZeroSizedBase,
2999  Builder.Bases, Builder.VBases);
3000  } else {
3001  Builder.layout(D);
3002  NewEntry = new (*this) ASTRecordLayout(
3003  *this, Builder.Size, Builder.Alignment, Builder.Alignment,
3004  Builder.RequiredAlignment,
3005  Builder.Size, Builder.FieldOffsets);
3006  }
3007  } else {
3008  if (const auto *RD = dyn_cast<CXXRecordDecl>(D)) {
3009  EmptySubobjectMap EmptySubobjects(*this, RD);
3010  ItaniumRecordLayoutBuilder Builder(*this, &EmptySubobjects);
3011  Builder.Layout(RD);
3012 
3013  // In certain situations, we are allowed to lay out objects in the
3014  // tail-padding of base classes. This is ABI-dependent.
3015  // FIXME: this should be stored in the record layout.
3016  bool skipTailPadding =
3017  mustSkipTailPadding(getTargetInfo().getCXXABI(), RD);
3018 
3019  // FIXME: This should be done in FinalizeLayout.
3020  CharUnits DataSize =
3021  skipTailPadding ? Builder.getSize() : Builder.getDataSize();
3022  CharUnits NonVirtualSize =
3023  skipTailPadding ? DataSize : Builder.NonVirtualSize;
3024  NewEntry = new (*this) ASTRecordLayout(
3025  *this, Builder.getSize(), Builder.Alignment, Builder.UnadjustedAlignment,
3026  /*RequiredAlignment : used by MS-ABI)*/
3027  Builder.Alignment, Builder.HasOwnVFPtr, RD->isDynamicClass(),
3028  CharUnits::fromQuantity(-1), DataSize, Builder.FieldOffsets,
3029  NonVirtualSize, Builder.NonVirtualAlignment,
3030  EmptySubobjects.SizeOfLargestEmptySubobject, Builder.PrimaryBase,
3031  Builder.PrimaryBaseIsVirtual, nullptr, false, false, Builder.Bases,
3032  Builder.VBases);
3033  } else {
3034  ItaniumRecordLayoutBuilder Builder(*this, /*EmptySubobjects=*/nullptr);
3035  Builder.Layout(D);
3036 
3037  NewEntry = new (*this) ASTRecordLayout(
3038  *this, Builder.getSize(), Builder.Alignment, Builder.UnadjustedAlignment,
3039  /*RequiredAlignment : used by MS-ABI)*/
3040  Builder.Alignment, Builder.getSize(), Builder.FieldOffsets);
3041  }
3042  }
3043 
3044  ASTRecordLayouts[D] = NewEntry;
3045 
3046  if (getLangOpts().DumpRecordLayouts) {
3047  llvm::outs() << "\n*** Dumping AST Record Layout\n";
3048  DumpRecordLayout(D, llvm::outs(), getLangOpts().DumpRecordLayoutsSimple);
3049  }
3050 
3051  return *NewEntry;
3052 }
3053 
3055  if (!getTargetInfo().getCXXABI().hasKeyFunctions())
3056  return nullptr;
3057 
3058  assert(RD->getDefinition() && "Cannot get key function for forward decl!");
3059  RD = RD->getDefinition();
3060 
3061  // Beware:
3062  // 1) computing the key function might trigger deserialization, which might
3063  // invalidate iterators into KeyFunctions
3064  // 2) 'get' on the LazyDeclPtr might also trigger deserialization and
3065  // invalidate the LazyDeclPtr within the map itself
3066  LazyDeclPtr Entry = KeyFunctions[RD];
3067  const Decl *Result =
3068  Entry ? Entry.get(getExternalSource()) : computeKeyFunction(*this, RD);
3069 
3070  // Store it back if it changed.
3071  if (Entry.isOffset() || Entry.isValid() != bool(Result))
3072  KeyFunctions[RD] = const_cast<Decl*>(Result);
3073 
3074  return cast_or_null<CXXMethodDecl>(Result);
3075 }
3076 
3078  assert(Method == Method->getFirstDecl() &&
3079  "not working with method declaration from class definition");
3080 
3081  // Look up the cache entry. Since we're working with the first
3082  // declaration, its parent must be the class definition, which is
3083  // the correct key for the KeyFunctions hash.
3084  const auto &Map = KeyFunctions;
3085  auto I = Map.find(Method->getParent());
3086 
3087  // If it's not cached, there's nothing to do.
3088  if (I == Map.end()) return;
3089 
3090  // If it is cached, check whether it's the target method, and if so,
3091  // remove it from the cache. Note, the call to 'get' might invalidate
3092  // the iterator and the LazyDeclPtr object within the map.
3093  LazyDeclPtr Ptr = I->second;
3094  if (Ptr.get(getExternalSource()) == Method) {
3095  // FIXME: remember that we did this for module / chained PCH state?
3096  KeyFunctions.erase(Method->getParent());
3097  }
3098 }
3099 
3100 static uint64_t getFieldOffset(const ASTContext &C, const FieldDecl *FD) {
3101  const ASTRecordLayout &Layout = C.getASTRecordLayout(FD->getParent());
3102  return Layout.getFieldOffset(FD->getFieldIndex());
3103 }
3104 
3105 uint64_t ASTContext::getFieldOffset(const ValueDecl *VD) const {
3106  uint64_t OffsetInBits;
3107  if (const FieldDecl *FD = dyn_cast<FieldDecl>(VD)) {
3108  OffsetInBits = ::getFieldOffset(*this, FD);
3109  } else {
3110  const IndirectFieldDecl *IFD = cast<IndirectFieldDecl>(VD);
3111 
3112  OffsetInBits = 0;
3113  for (const NamedDecl *ND : IFD->chain())
3114  OffsetInBits += ::getFieldOffset(*this, cast<FieldDecl>(ND));
3115  }
3116 
3117  return OffsetInBits;
3118 }
3119 
3121  const ObjCImplementationDecl *ID,
3122  const ObjCIvarDecl *Ivar) const {
3123  const ObjCInterfaceDecl *Container = Ivar->getContainingInterface();
3124 
3125  // FIXME: We should eliminate the need to have ObjCImplementationDecl passed
3126  // in here; it should never be necessary because that should be the lexical
3127  // decl context for the ivar.
3128 
3129  // If we know have an implementation (and the ivar is in it) then
3130  // look up in the implementation layout.
3131  const ASTRecordLayout *RL;
3132  if (ID && declaresSameEntity(ID->getClassInterface(), Container))
3133  RL = &getASTObjCImplementationLayout(ID);
3134  else
3135  RL = &getASTObjCInterfaceLayout(Container);
3136 
3137  // Compute field index.
3138  //
3139  // FIXME: The index here is closely tied to how ASTContext::getObjCLayout is
3140  // implemented. This should be fixed to get the information from the layout
3141  // directly.
3142  unsigned Index = 0;
3143 
3144  for (const ObjCIvarDecl *IVD = Container->all_declared_ivar_begin();
3145  IVD; IVD = IVD->getNextIvar()) {
3146  if (Ivar == IVD)
3147  break;
3148  ++Index;
3149  }
3150  assert(Index < RL->getFieldCount() && "Ivar is not inside record layout!");
3151 
3152  return RL->getFieldOffset(Index);
3153 }
3154 
3155 /// getObjCLayout - Get or compute information about the layout of the
3156 /// given interface.
3157 ///
3158 /// \param Impl - If given, also include the layout of the interface's
3159 /// implementation. This may differ by including synthesized ivars.
3160 const ASTRecordLayout &
3161 ASTContext::getObjCLayout(const ObjCInterfaceDecl *D,
3162  const ObjCImplementationDecl *Impl) const {
3163  // Retrieve the definition
3164  if (D->hasExternalLexicalStorage() && !D->getDefinition())
3165  getExternalSource()->CompleteType(const_cast<ObjCInterfaceDecl*>(D));
3166  D = D->getDefinition();
3167  assert(D && D->isThisDeclarationADefinition() && "Invalid interface decl!");
3168 
3169  // Look up this layout, if already laid out, return what we have.
3170  const ObjCContainerDecl *Key =
3171  Impl ? (const ObjCContainerDecl*) Impl : (const ObjCContainerDecl*) D;
3172  if (const ASTRecordLayout *Entry = ObjCLayouts[Key])
3173  return *Entry;
3174 
3175  // Add in synthesized ivar count if laying out an implementation.
3176  if (Impl) {
3177  unsigned SynthCount = CountNonClassIvars(D);
3178  // If there aren't any synthesized ivars then reuse the interface
3179  // entry. Note we can't cache this because we simply free all
3180  // entries later; however we shouldn't look up implementations
3181  // frequently.
3182  if (SynthCount == 0)
3183  return getObjCLayout(D, nullptr);
3184  }
3185 
3186  ItaniumRecordLayoutBuilder Builder(*this, /*EmptySubobjects=*/nullptr);
3187  Builder.Layout(D);
3188 
3189  const ASTRecordLayout *NewEntry =
3190  new (*this) ASTRecordLayout(*this, Builder.getSize(),
3191  Builder.Alignment,
3192  Builder.UnadjustedAlignment,
3193  /*RequiredAlignment : used by MS-ABI)*/
3194  Builder.Alignment,
3195  Builder.getDataSize(),
3196  Builder.FieldOffsets);
3197 
3198  ObjCLayouts[Key] = NewEntry;
3199 
3200  return *NewEntry;
3201 }
3202 
3203 static void PrintOffset(raw_ostream &OS,
3204  CharUnits Offset, unsigned IndentLevel) {
3205  OS << llvm::format("%10" PRId64 " | ", (int64_t)Offset.getQuantity());
3206  OS.indent(IndentLevel * 2);
3207 }
3208 
3209 static void PrintBitFieldOffset(raw_ostream &OS, CharUnits Offset,
3210  unsigned Begin, unsigned Width,
3211  unsigned IndentLevel) {
3212  llvm::SmallString<10> Buffer;
3213  {
3214  llvm::raw_svector_ostream BufferOS(Buffer);
3215  BufferOS << Offset.getQuantity() << ':';
3216  if (Width == 0) {
3217  BufferOS << '-';
3218  } else {
3219  BufferOS << Begin << '-' << (Begin + Width - 1);
3220  }
3221  }
3222 
3223  OS << llvm::right_justify(Buffer, 10) << " | ";
3224  OS.indent(IndentLevel * 2);
3225 }
3226 
3227 static void PrintIndentNoOffset(raw_ostream &OS, unsigned IndentLevel) {
3228  OS << " | ";
3229  OS.indent(IndentLevel * 2);
3230 }
3231 
3232 static void DumpRecordLayout(raw_ostream &OS, const RecordDecl *RD,
3233  const ASTContext &C,
3234  CharUnits Offset,
3235  unsigned IndentLevel,
3236  const char* Description,
3237  bool PrintSizeInfo,
3238  bool IncludeVirtualBases) {
3239  const ASTRecordLayout &Layout = C.getASTRecordLayout(RD);
3240  auto CXXRD = dyn_cast<CXXRecordDecl>(RD);
3241 
3242  PrintOffset(OS, Offset, IndentLevel);
3243  OS << C.getTypeDeclType(const_cast<RecordDecl*>(RD)).getAsString();
3244  if (Description)
3245  OS << ' ' << Description;
3246  if (CXXRD && CXXRD->isEmpty())
3247  OS << " (empty)";
3248  OS << '\n';
3249 
3250  IndentLevel++;
3251 
3252  // Dump bases.
3253  if (CXXRD) {
3254  const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
3255  bool HasOwnVFPtr = Layout.hasOwnVFPtr();
3256  bool HasOwnVBPtr = Layout.hasOwnVBPtr();
3257 
3258  // Vtable pointer.
3259  if (CXXRD->isDynamicClass() && !PrimaryBase && !isMsLayout(C)) {
3260  PrintOffset(OS, Offset, IndentLevel);
3261  OS << '(' << *RD << " vtable pointer)\n";
3262  } else if (HasOwnVFPtr) {
3263  PrintOffset(OS, Offset, IndentLevel);
3264  // vfptr (for Microsoft C++ ABI)
3265  OS << '(' << *RD << " vftable pointer)\n";
3266  }
3267 
3268  // Collect nvbases.
3270  for (const CXXBaseSpecifier &Base : CXXRD->bases()) {
3271  assert(!Base.getType()->isDependentType() &&
3272  "Cannot layout class with dependent bases.");
3273  if (!Base.isVirtual())
3274  Bases.push_back(Base.getType()->getAsCXXRecordDecl());
3275  }
3276 
3277  // Sort nvbases by offset.
3278  std::stable_sort(Bases.begin(), Bases.end(),
3279  [&](const CXXRecordDecl *L, const CXXRecordDecl *R) {
3280  return Layout.getBaseClassOffset(L) < Layout.getBaseClassOffset(R);
3281  });
3282 
3283  // Dump (non-virtual) bases
3284  for (const CXXRecordDecl *Base : Bases) {
3285  CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base);
3286  DumpRecordLayout(OS, Base, C, BaseOffset, IndentLevel,
3287  Base == PrimaryBase ? "(primary base)" : "(base)",
3288  /*PrintSizeInfo=*/false,
3289  /*IncludeVirtualBases=*/false);
3290  }
3291 
3292  // vbptr (for Microsoft C++ ABI)
3293  if (HasOwnVBPtr) {
3294  PrintOffset(OS, Offset + Layout.getVBPtrOffset(), IndentLevel);
3295  OS << '(' << *RD << " vbtable pointer)\n";
3296  }
3297  }
3298 
3299  // Dump fields.
3300  uint64_t FieldNo = 0;
3301  for (RecordDecl::field_iterator I = RD->field_begin(),
3302  E = RD->field_end(); I != E; ++I, ++FieldNo) {
3303  const FieldDecl &Field = **I;
3304  uint64_t LocalFieldOffsetInBits = Layout.getFieldOffset(FieldNo);
3305  CharUnits FieldOffset =
3306  Offset + C.toCharUnitsFromBits(LocalFieldOffsetInBits);
3307 
3308  // Recursively dump fields of record type.
3309  if (auto RT = Field.getType()->getAs<RecordType>()) {
3310  DumpRecordLayout(OS, RT->getDecl(), C, FieldOffset, IndentLevel,
3311  Field.getName().data(),
3312  /*PrintSizeInfo=*/false,
3313  /*IncludeVirtualBases=*/true);
3314  continue;
3315  }
3316 
3317  if (Field.isBitField()) {
3318  uint64_t LocalFieldByteOffsetInBits = C.toBits(FieldOffset - Offset);
3319  unsigned Begin = LocalFieldOffsetInBits - LocalFieldByteOffsetInBits;
3320  unsigned Width = Field.getBitWidthValue(C);
3321  PrintBitFieldOffset(OS, FieldOffset, Begin, Width, IndentLevel);
3322  } else {
3323  PrintOffset(OS, FieldOffset, IndentLevel);
3324  }
3325  OS << Field.getType().getAsString() << ' ' << Field << '\n';
3326  }
3327 
3328  // Dump virtual bases.
3329  if (CXXRD && IncludeVirtualBases) {
3330  const ASTRecordLayout::VBaseOffsetsMapTy &VtorDisps =
3331  Layout.getVBaseOffsetsMap();
3332 
3333  for (const CXXBaseSpecifier &Base : CXXRD->vbases()) {
3334  assert(Base.isVirtual() && "Found non-virtual class!");
3335  const CXXRecordDecl *VBase = Base.getType()->getAsCXXRecordDecl();
3336 
3337  CharUnits VBaseOffset = Offset + Layout.getVBaseClassOffset(VBase);
3338 
3339  if (VtorDisps.find(VBase)->second.hasVtorDisp()) {
3340  PrintOffset(OS, VBaseOffset - CharUnits::fromQuantity(4), IndentLevel);
3341  OS << "(vtordisp for vbase " << *VBase << ")\n";
3342  }
3343 
3344  DumpRecordLayout(OS, VBase, C, VBaseOffset, IndentLevel,
3345  VBase == Layout.getPrimaryBase() ?
3346  "(primary virtual base)" : "(virtual base)",
3347  /*PrintSizeInfo=*/false,
3348  /*IncludeVirtualBases=*/false);
3349  }
3350  }
3351 
3352  if (!PrintSizeInfo) return;
3353 
3354  PrintIndentNoOffset(OS, IndentLevel - 1);
3355  OS << "[sizeof=" << Layout.getSize().getQuantity();
3356  if (CXXRD && !isMsLayout(C))
3357  OS << ", dsize=" << Layout.getDataSize().getQuantity();
3358  OS << ", align=" << Layout.getAlignment().getQuantity();
3359 
3360  if (CXXRD) {
3361  OS << ",\n";
3362  PrintIndentNoOffset(OS, IndentLevel - 1);
3363  OS << " nvsize=" << Layout.getNonVirtualSize().getQuantity();
3364  OS << ", nvalign=" << Layout.getNonVirtualAlignment().getQuantity();
3365  }
3366  OS << "]\n";
3367 }
3368 
3370  raw_ostream &OS,
3371  bool Simple) const {
3372  if (!Simple) {
3373  ::DumpRecordLayout(OS, RD, *this, CharUnits(), 0, nullptr,
3374  /*PrintSizeInfo*/true,
3375  /*IncludeVirtualBases=*/true);
3376  return;
3377  }
3378 
3379  // The "simple" format is designed to be parsed by the
3380  // layout-override testing code. There shouldn't be any external
3381  // uses of this format --- when LLDB overrides a layout, it sets up
3382  // the data structures directly --- so feel free to adjust this as
3383  // you like as long as you also update the rudimentary parser for it
3384  // in libFrontend.
3385 
3386  const ASTRecordLayout &Info = getASTRecordLayout(RD);
3387  OS << "Type: " << getTypeDeclType(RD).getAsString() << "\n";
3388  OS << "\nLayout: ";
3389  OS << "<ASTRecordLayout\n";
3390  OS << " Size:" << toBits(Info.getSize()) << "\n";
3391  if (!isMsLayout(*this))
3392  OS << " DataSize:" << toBits(Info.getDataSize()) << "\n";
3393  OS << " Alignment:" << toBits(Info.getAlignment()) << "\n";
3394  OS << " FieldOffsets: [";
3395  for (unsigned i = 0, e = Info.getFieldCount(); i != e; ++i) {
3396  if (i) OS << ", ";
3397  OS << Info.getFieldOffset(i);
3398  }
3399  OS << "]>\n";
3400 }
static uint64_t getFieldOffset(const ASTContext &C, const FieldDecl *FD)
Defines the clang::ASTContext interface.
CharUnits alignTo(const CharUnits &Align) const
alignTo - Returns the next integer (mod 2**64) that is greater than or equal to this quantity and is ...
Definition: CharUnits.h:183
Represents a function declaration or definition.
Definition: Decl.h:1737
Only allocate objects in the tail padding of a base class if the base class is not POD according to t...
Definition: TargetCXXABI.h:301
static DiagnosticBuilder Diag(DiagnosticsEngine *Diags, const LangOptions &Features, FullSourceLoc TokLoc, const char *TokBegin, const char *TokRangeBegin, const char *TokRangeEnd, unsigned DiagID)
Produce a diagnostic highlighting some portion of a literal.
bool isPrimaryBaseVirtual() const
isPrimaryBaseVirtual - Get whether the primary base for this record is virtual or not...
Definition: RecordLayout.h:225
A (possibly-)qualified type.
Definition: Type.h:634
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:822
Attempt to be ABI-compatible with code generated by Clang 6.0.x (SVN r321711).
The basic abstraction for the target C++ ABI.
Definition: TargetCXXABI.h:23
bool isThisDeclarationADefinition() const
Determine whether this particular declaration of this class is actually also a definition.
Definition: DeclObjC.h:1529
const ASTRecordLayout & getASTRecordLayout(const RecordDecl *D) const
Get or compute information about the layout of the specified record (struct/union/class) D...
QualType getPointeeType() const
If this is a pointer, ObjC object pointer, or block pointer, this returns the respective pointee...
Definition: Type.cpp:505
const llvm::Triple & getTriple() const
Returns the target triple of the primary target.
Definition: TargetInfo.h:962
CharUnits getBaseClassOffset(const CXXRecordDecl *Base) const
getBaseClassOffset - Get the offset, in chars, for the given base class.
Definition: RecordLayout.h:232
unsigned getNumVBases() const
Retrieves the number of virtual base classes of this class.
Definition: DeclCXX.h:837
Decl - This represents one declaration (or definition), e.g.
Definition: DeclBase.h:86
bool isPOD() const
Whether this class is a POD-type (C++ [class]p4)
Definition: DeclCXX.h:1311
unsigned getFieldIndex() const
Returns the index of this field within its record, as appropriate for passing to ASTRecordLayout::get...
Definition: Decl.cpp:3802
const RecordDecl * getParent() const
Returns the parent of this field declaration, which is the struct in which this field is defined...
Definition: Decl.h:2762
The base class of the type hierarchy.
Definition: Type.h:1409
DiagnosticsEngine & getDiagnostics() const
DiagnosticBuilder Report(SourceLocation Loc, unsigned DiagID)
Issue the message to the client.
Definition: Diagnostic.h:1294
Represents an array type, per C99 6.7.5.2 - Array Declarators.
Definition: Type.h:2817
bool isZero() const
isZero - Test whether the quantity equals zero.
Definition: CharUnits.h:115
const TargetInfo & getTargetInfo() const
Definition: ASTContext.h:689
CharUnits getAlignment() const
getAlignment - Get the record alignment in characters.
Definition: RecordLayout.h:176
unsigned getCharWidth() const
Definition: TargetInfo.h:380
QualType getElementType() const
Definition: Type.h:2852
bool isCompleteDefinition() const
Return true if this decl has its body fully specified.
Definition: Decl.h:3168
bool hasVBPtr() const
hasVBPtr - Does this class have a virtual function table pointer.
Definition: RecordLayout.h:285
const T * getAs() const
Member-template getAs<specific type>&#39;.
Definition: Type.h:6761
unsigned getCharAlign() const
Definition: TargetInfo.h:381
The "__interface" keyword.
Definition: Type.h:5041
bool hasOwnVFPtr() const
hasOwnVFPtr - Does this class provide its own virtual-function table pointer, rather than inheriting ...
Definition: RecordLayout.h:259
bool isInvalidDecl() const
Definition: DeclBase.h:544
unsigned getZeroLengthBitfieldBoundary() const
Get the fixed alignment value in bits for a member that follows a zero length bitfield.
Definition: TargetInfo.h:685
bool mayInsertExtraPadding(bool EmitRemark=false) const
Whether we are allowed to insert extra padding between fields.
Definition: Decl.cpp:4197
IdentifierInfo * getIdentifier() const
Get the identifier that names this declaration, if there is one.
Definition: Decl.h:269
Represents a struct/union/class.
Definition: Decl.h:3592
uint64_t getPointerWidth(unsigned AddrSpace) const
Return the width of pointers on this target, for the specified address space.
Definition: TargetInfo.h:358
bool isEmpty() const
Determine whether this is an empty class in the sense of (C++11 [meta.unary.prop]).
Definition: DeclCXX.h:1326
TargetCXXABI getCXXABI() const
Get the C++ ABI currently in use.
Definition: TargetInfo.h:1031
Holds long-lived AST nodes (such as types and decls) that can be referred to throughout the semantic ...
Definition: ASTContext.h:154
RecordDecl * getDefinition() const
Returns the RecordDecl that actually defines this struct/union/class.
Definition: Decl.h:3773
field_range fields() const
Definition: Decl.h:3783
Represents a member of a struct/union/class.
Definition: Decl.h:2578
bool hasUserDeclaredDestructor() const
Determine whether this class has a user-declared destructor.
Definition: DeclCXX.h:1178
static CharUnits Zero()
Zero - Construct a CharUnits quantity of zero.
Definition: CharUnits.h:52
CharUnits getVBaseClassOffset(const CXXRecordDecl *VBase) const
getVBaseClassOffset - Get the offset, in chars, for the given base class.
Definition: RecordLayout.h:240
method_iterator method_begin() const
Method begin iterator.
Definition: DeclCXX.h:870
uint64_t lookupFieldBitOffset(const ObjCInterfaceDecl *OID, const ObjCImplementationDecl *ID, const ObjCIvarDecl *Ivar) const
Get the offset of an ObjCIvarDecl in bits.
const ASTRecordLayout & getASTObjCInterfaceLayout(const ObjCInterfaceDecl *D) const
Get or compute information about the layout of the specified Objective-C interface.
specific_decl_iterator< FieldDecl > field_iterator
Definition: Decl.h:3780
bool canKeyFunctionBeInline() const
Can an out-of-line inline function serve as a key function?
Definition: TargetCXXABI.h:258
uint64_t getConstantArrayElementCount(const ConstantArrayType *CA) const
Return number of constant array elements.
bool isBitField() const
Determines whether this field is a bitfield.
Definition: Decl.h:2656
ObjCContainerDecl - Represents a container for method declarations.
Definition: DeclObjC.h:968
TagKind getTagKind() const
Definition: Decl.h:3242
CharUnits - This is an opaque type for sizes expressed in character units.
Definition: CharUnits.h:37
bool endsWithZeroSizedObject() const
Definition: RecordLayout.h:294
ArrayRef< NamedDecl * > chain() const
Definition: Decl.h:2846
unsigned Align
Definition: ASTContext.h:144
field_iterator field_begin() const
Definition: Decl.cpp:4150
unsigned getBitWidthValue(const ASTContext &Ctx) const
Definition: Decl.cpp:3792
bool declaresSameEntity(const Decl *D1, const Decl *D2)
Determine whether two declarations declare the same entity.
Definition: DeclBase.h:1160
const VBaseOffsetsMapTy & getVBaseOffsetsMap() const
Definition: RecordLayout.h:315
bool isAlignmentRequired(const Type *T) const
Determine if the alignment the type has was required using an alignment attribute.
bool useZeroLengthBitfieldAlignment() const
Check whether zero length bitfields should force alignment of the next member.
Definition: TargetInfo.h:679
Represents an ObjC class declaration.
Definition: DeclObjC.h:1171
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:419
CanQualType UnsignedCharTy
Definition: ASTContext.h:1025
lookup_result lookup(DeclarationName Name) const
lookup - Find the declarations (if any) with the given Name in this context.
Definition: DeclBase.cpp:1598
bool hasAttr() const
Definition: DeclBase.h:533
static CharUnits One()
One - Construct a CharUnits quantity of one.
Definition: CharUnits.h:57
A little helper class used to produce diagnostics.
Definition: Diagnostic.h:1042
CXXRecordDecl * getAsCXXRecordDecl() const
Retrieves the CXXRecordDecl that this type refers to, either because the type is a RecordType or beca...
Definition: Type.cpp:1635
bool isDynamicClass() const
Definition: DeclCXX.h:788
bool useExplicitBitFieldAlignment() const
Check whether explicit bitfield alignment attributes should be.
Definition: TargetInfo.h:691
static void PrintOffset(raw_ostream &OS, CharUnits Offset, unsigned IndentLevel)
TemplateSpecializationKind getTemplateSpecializationKind() const
Determine whether this particular class is a specialization or instantiation of a class template or m...
Definition: DeclCXX.cpp:1637
QuantityType getQuantity() const
getQuantity - Get the raw integer representation of this quantity.
Definition: CharUnits.h:178
unsigned Offset
Definition: Format.cpp:1630
ASTRecordLayout - This class contains layout information for one RecordDecl, which is a struct/union/...
Definition: RecordLayout.h:38
bool isMsStruct(const ASTContext &C) const
Get whether or not this is an ms_struct which can be turned on with an attribute, pragma...
Definition: Decl.cpp:4167
bool isInlineSpecified() const
Determine whether the "inline" keyword was specified for this function.
Definition: Decl.h:2341
Represent the declaration of a variable (in which case it is an lvalue) a function (in which case it ...
Definition: Decl.h:636
SourceLocation End
bool isNearlyEmpty(const CXXRecordDecl *RD) const
field_iterator field_end() const
Definition: Decl.h:3786
#define bool
Definition: stdbool.h:31
CharUnits getSizeOfLargestEmptySubobject() const
Definition: RecordLayout.h:247
overridden_method_range overridden_methods() const
Definition: DeclCXX.cpp:2185
CharUnits getTypeAlignInChars(QualType T) const
Return the ABI-specified alignment of a (complete) type T, in characters.
CXXRecordDecl * getDefinition() const
Definition: DeclCXX.h:768
ObjCInterfaceDecl * getSuperClass() const
Definition: DeclObjC.cpp:337
SourceLocation Begin
const CXXRecordDecl * getPrimaryBase() const
getPrimaryBase - Get the primary base for this record.
Definition: RecordLayout.h:217
static CharUnits fromQuantity(QuantityType Quantity)
fromQuantity - Construct a CharUnits quantity from a raw integer type.
Definition: CharUnits.h:62
unsigned getFieldCount() const
getFieldCount - Get the number of fields in the layout.
Definition: RecordLayout.h:186
bool isTrivial() const
Determine whether this class is considered trivial.
Definition: DeclCXX.h:1544
bool isPolymorphic() const
Whether this class is polymorphic (C++ [class.virtual]), which means that the class contains or inher...
Definition: DeclCXX.h:1336
bool hasExtendableVFPtr() const
hasVFPtr - Does this class have a virtual function table pointer that can be extended by a derived cl...
Definition: RecordLayout.h:267
unsigned getMaxAlignment() const
getMaxAlignment - return the maximum alignment specified by attributes on this decl, 0 if there are none.
Definition: DeclBase.cpp:383
method_iterator method_end() const
Method past-the-end iterator.
Definition: DeclCXX.h:875
CharUnits getVBPtrOffset() const
getVBPtrOffset - Get the offset for virtual base table pointer.
Definition: RecordLayout.h:305
const Type * getBaseElementTypeUnsafe() const
Get the base element type of this type, potentially discarding type qualifiers.
Definition: Type.h:6701
CharUnits getRequiredAlignment() const
Definition: RecordLayout.h:290
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:1395
The result type of a method or function.
This template specialization was implicitly instantiated from a template.
Definition: Specifiers.h:151
void getIndirectPrimaryBases(CXXIndirectPrimaryBaseSet &Bases) const
Get the indirect primary bases for this class.
bool isNull() const
Return true if this QualType doesn&#39;t point to a type yet.
Definition: Type.h:699
decl_type * getFirstDecl()
Return the first declaration of this declaration or itself if this is the only declaration.
Definition: Redeclarable.h:215
static bool recordUsesEBO(const RecordDecl *RD)
RecordDecl * getDecl() const
Definition: Type.h:4385
Abstract interface for external sources of AST nodes.
uint64_t getFieldOffset(unsigned FieldNo) const
getFieldOffset - Get the offset of the given field index, in bits.
Definition: RecordLayout.h:190
static uint64_t roundUpSizeToCharAlignment(uint64_t Size, const ASTContext &Context)
#define false
Definition: stdbool.h:33
The "struct" keyword.
Definition: Type.h:5038
Only allocate objects in the tail padding of a base class if the base class is not POD according to t...
Definition: TargetCXXABI.h:305
Encodes a location in the source.
A set of all the primary bases for a class.
static void PrintIndentNoOffset(raw_ostream &OS, unsigned IndentLevel)
QualType getBaseElementType(const ArrayType *VAT) const
Return the innermost element type of an array type.
Represents a static or instance method of a struct/union/class.
Definition: DeclCXX.h:2048
const ConstantArrayType * getAsConstantArrayType(QualType T) const
Definition: ASTContext.h:2426
const ArrayType * getAsArrayType(QualType T) const
Type Query functions.
bool hasExternalLexicalStorage() const
Whether this DeclContext has external storage containing additional declarations that are lexically i...
Definition: DeclBase.h:2315
This template specialization was instantiated from a template due to an explicit instantiation defini...
Definition: Specifiers.h:163
CharUnits getDataSize() const
getDataSize() - Get the record data size, which is the record size without tail padding, in characters.
Definition: RecordLayout.h:196
bool useBitFieldTypeAlignment() const
Check whether the alignment of bit-field types is respected when laying out structures.
Definition: TargetInfo.h:673
MSVtorDispAttr::Mode getMSVtorDispMode() const
Controls when vtordisps will be emitted if this record is used as a virtual base. ...
static unsigned getPaddingDiagFromTagKind(TagTypeKind Tag)
Get diagnostic select index for tag kind for field padding diagnostic message.
bool hasFlexibleArrayMember() const
Definition: Decl.h:3646
bool isValid() const
Whether this pointer is non-NULL.
ASTContext & operator=(const ASTContext &)=delete
std::pair< CharUnits, CharUnits > getTypeInfoInChars(const Type *T) const
CanQualType UnsignedShortTy
Definition: ASTContext.h:1025
ObjCIvarDecl * getNextIvar()
Definition: DeclObjC.h:1977
CharUnits getNonVirtualAlignment() const
getNonVirtualSize - Get the non-virtual alignment (in chars) of an object, which is the alignment of ...
Definition: RecordLayout.h:210
TagTypeKind
The kind of a tag type.
Definition: Type.h:5036
const ObjCInterfaceDecl * getClassInterface() const
Definition: DeclObjC.h:2439
Dataflow Directional Tag Classes.
CharUnits getSize() const
getSize - Get the record size in characters.
Definition: RecordLayout.h:183
Represents a field injected from an anonymous union/struct into the parent scope. ...
Definition: Decl.h:2824
CanQualType UnsignedLongLongTy
Definition: ASTContext.h:1026
ObjCInterfaceDecl * getDefinition()
Retrieve the definition of this class, or NULL if this class has been forward-declared (with @class) ...
Definition: DeclObjC.h:1548
This template specialization was instantiated from a template due to an explicit instantiation declar...
Definition: Specifiers.h:159
bool hasUserDeclaredConstructor() const
Determine whether this class has any user-declared constructors.
Definition: DeclCXX.h:982
TailPaddingUseRules getTailPaddingUseRules() const
Definition: TargetCXXABI.h:307
bool isCXX11StandardLayout() const
Determine whether this class was standard-layout per C++11 [class]p7, specifically using the C++11 ru...
Definition: DeclCXX.h:1351
static std::string getAsString(SplitQualType split, const PrintingPolicy &Policy)
Definition: Type.h:967
const CXXRecordDecl * getParent() const
Returns the parent of this method declaration, which is the class in which this method is defined...
Definition: DeclCXX.h:2173
void DumpRecordLayout(const RecordDecl *RD, raw_ostream &OS, bool Simple=false) const
const ObjCInterfaceDecl * getContainingInterface() const
Return the class interface that this ivar is logically contained in; this is either the interface whe...
Definition: DeclObjC.cpp:1789
TemplateSpecializationKind
Describes the kind of template specialization that a particular template specialization declaration r...
Definition: Specifiers.h:145
ExternalASTSource * getExternalSource() const
Retrieve a pointer to the external AST source associated with this AST context, if any...
Definition: ASTContext.h:1082
T * get(ExternalASTSource *Source) const
Retrieve the pointer to the AST node that this lazy pointer points to.
specific_decl_iterator - Iterates over a subrange of declarations stored in a DeclContext, providing only those that are of type SpecificDecl (or a class derived from it).
Definition: DeclBase.h:2020
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:2551
bool isIncompleteArrayType() const
Definition: Type.h:6358
A helper class that allows the use of isa/cast/dyncast to detect TagType objects of structs/unions/cl...
Definition: Type.h:4375
CanQualType UnsignedLongTy
Definition: ASTContext.h:1025
static bool RequiresVtordisp(const llvm::SmallPtrSetImpl< const CXXRecordDecl *> &BasesWithOverriddenMethods, const CXXRecordDecl *RD)
T * getAttr() const
Definition: DeclBase.h:529
uint64_t getCharWidth() const
Return the size of the character type, in bits.
Definition: ASTContext.h:2076
void setNonKeyFunction(const CXXMethodDecl *method)
Observe that the given method cannot be a key function.
Base for LValueReferenceType and RValueReferenceType.
Definition: Type.h:2678
The "class" keyword.
Definition: Type.h:5047
Represents a base class of a C++ class.
Definition: DeclCXX.h:191
uint64_t getTypeSize(QualType T) const
Return the size of the specified (complete) type T, in bits.
Definition: ASTContext.h:2072
uint64_t getFieldOffset(const ValueDecl *FD) const
Get the offset of a FieldDecl or IndirectFieldDecl, in bits.
CharUnits toCharUnitsFromBits(int64_t BitSize) const
Convert a size in bits to a size in characters.
Defines the C++ Decl subclasses, other than those for templates (found in DeclTemplate.h) and friends (in DeclFriend.h).
int64_t toBits(CharUnits CharSize) const
Convert a size in characters to a size in bits.
const CXXMethodDecl * getCurrentKeyFunction(const CXXRecordDecl *RD)
Get our current best idea for the key function of the given record decl, or nullptr if there isn&#39;t on...
Represents a C++ struct/union/class.
Definition: DeclCXX.h:299
TypeInfo getTypeInfo(const Type *T) const
Get the size and alignment of the specified complete type in bits.
ObjCIvarDecl - Represents an ObjC instance variable.
Definition: DeclObjC.h:1944
CharUnits getNonVirtualSize() const
getNonVirtualSize - Get the non-virtual size (in chars) of an object, which is the size of the object...
Definition: RecordLayout.h:202
static bool isMsLayout(const ASTContext &Context)
static unsigned getCharWidth(tok::TokenKind kind, const TargetInfo &Target)
This class is used for builtin types like &#39;int&#39;.
Definition: Type.h:2396
static const CXXMethodDecl * computeKeyFunction(ASTContext &Context, const CXXRecordDecl *RD)
The tail-padding of a base class is always theoretically available, even if it&#39;s POD.
Definition: TargetCXXABI.h:296
llvm::DenseMap< const CXXRecordDecl *, VBaseInfo > VBaseOffsetsMapTy
Definition: RecordLayout.h:59
bool isOffset() const
Whether this pointer is currently stored as an offset.
uint64_t getPointerAlign(unsigned AddrSpace) const
Definition: TargetInfo.h:361
Defines the clang::TargetInfo interface.
bool isMicrosoft() const
Is this ABI an MSVC-compatible ABI?
Definition: TargetCXXABI.h:153
StringRef getName() const
Get the name of identifier for this declaration as a StringRef.
Definition: Decl.h:275
static void PrintBitFieldOffset(raw_ostream &OS, CharUnits Offset, unsigned Begin, unsigned Width, unsigned IndentLevel)
uint64_t Width
Definition: ASTContext.h:143
__DEVICE__ int max(int __a, int __b)
bool isUnion() const
Definition: Decl.h:3251
__DEVICE__ int min(int __a, int __b)
CharUnits getTypeSizeInChars(QualType T) const
Return the size of the specified (complete) type T, in characters.
QualType getType() const
Definition: Decl.h:647
This represents a decl that may have a name.
Definition: Decl.h:248
ObjCIvarDecl * all_declared_ivar_begin()
all_declared_ivar_begin - return first ivar declared in this class, its extensions and its implementa...
Definition: DeclObjC.cpp:1591
bool hasOwnVBPtr() const
hasOwnVBPtr - Does this class provide its own virtual-base table pointer, rather than inheriting one ...
Definition: RecordLayout.h:279
unsigned getTargetAddressSpace(QualType T) const
Definition: ASTContext.h:2517
const LangOptions & getLangOpts() const
Definition: ASTContext.h:706
Represents the canonical version of C arrays with a specified constant size.
Definition: Type.h:2877
base_class_range vbases()
Definition: DeclCXX.h:839
SourceLocation getLocation() const
Definition: DeclBase.h:420
bool isExternallyVisible() const
Definition: Decl.h:379
CanQualType UnsignedIntTy
Definition: ASTContext.h:1025
bool leadsWithZeroSizedBase() const
Definition: RecordLayout.h:298
method_range methods() const
Definition: DeclCXX.h:864