clang  10.0.0svn
RecordLayoutBuilder.cpp
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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, CharUnits Offset,
131  bool PlacingOverlappingField);
132  void UpdateEmptyFieldSubobjects(const FieldDecl *FD, CharUnits Offset,
133  bool PlacingOverlappingField);
134 
135  /// AnyEmptySubobjectsBeyondOffset - Returns whether there are any empty
136  /// subobjects beyond the given offset.
137  bool AnyEmptySubobjectsBeyondOffset(CharUnits Offset) const {
138  return Offset <= MaxEmptyClassOffset;
139  }
140 
141  CharUnits
142  getFieldOffset(const ASTRecordLayout &Layout, unsigned FieldNo) const {
143  uint64_t FieldOffset = Layout.getFieldOffset(FieldNo);
144  assert(FieldOffset % CharWidth == 0 &&
145  "Field offset not at char boundary!");
146 
147  return Context.toCharUnitsFromBits(FieldOffset);
148  }
149 
150 protected:
151  bool CanPlaceSubobjectAtOffset(const CXXRecordDecl *RD,
152  CharUnits Offset) const;
153 
154  bool CanPlaceBaseSubobjectAtOffset(const BaseSubobjectInfo *Info,
155  CharUnits Offset);
156 
157  bool CanPlaceFieldSubobjectAtOffset(const CXXRecordDecl *RD,
158  const CXXRecordDecl *Class,
159  CharUnits Offset) const;
160  bool CanPlaceFieldSubobjectAtOffset(const FieldDecl *FD,
161  CharUnits Offset) const;
162 
163 public:
164  /// This holds the size of the largest empty subobject (either a base
165  /// or a member). Will be zero if the record being built doesn't contain
166  /// any empty classes.
167  CharUnits SizeOfLargestEmptySubobject;
168 
169  EmptySubobjectMap(const ASTContext &Context, const CXXRecordDecl *Class)
170  : Context(Context), CharWidth(Context.getCharWidth()), Class(Class) {
171  ComputeEmptySubobjectSizes();
172  }
173 
174  /// CanPlaceBaseAtOffset - Return whether the given base class can be placed
175  /// at the given offset.
176  /// Returns false if placing the record will result in two components
177  /// (direct or indirect) of the same type having the same offset.
178  bool CanPlaceBaseAtOffset(const BaseSubobjectInfo *Info,
179  CharUnits Offset);
180 
181  /// CanPlaceFieldAtOffset - Return whether a field can be placed at the given
182  /// offset.
183  bool CanPlaceFieldAtOffset(const FieldDecl *FD, CharUnits Offset);
184 };
185 
186 void EmptySubobjectMap::ComputeEmptySubobjectSizes() {
187  // Check the bases.
188  for (const CXXBaseSpecifier &Base : Class->bases()) {
189  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
190 
191  CharUnits EmptySize;
192  const ASTRecordLayout &Layout = Context.getASTRecordLayout(BaseDecl);
193  if (BaseDecl->isEmpty()) {
194  // If the class decl is empty, get its size.
195  EmptySize = Layout.getSize();
196  } else {
197  // Otherwise, we get the largest empty subobject for the decl.
198  EmptySize = Layout.getSizeOfLargestEmptySubobject();
199  }
200 
201  if (EmptySize > SizeOfLargestEmptySubobject)
202  SizeOfLargestEmptySubobject = EmptySize;
203  }
204 
205  // Check the fields.
206  for (const FieldDecl *FD : Class->fields()) {
207  const RecordType *RT =
208  Context.getBaseElementType(FD->getType())->getAs<RecordType>();
209 
210  // We only care about record types.
211  if (!RT)
212  continue;
213 
214  CharUnits EmptySize;
215  const CXXRecordDecl *MemberDecl = RT->getAsCXXRecordDecl();
216  const ASTRecordLayout &Layout = Context.getASTRecordLayout(MemberDecl);
217  if (MemberDecl->isEmpty()) {
218  // If the class decl is empty, get its size.
219  EmptySize = Layout.getSize();
220  } else {
221  // Otherwise, we get the largest empty subobject for the decl.
222  EmptySize = Layout.getSizeOfLargestEmptySubobject();
223  }
224 
225  if (EmptySize > SizeOfLargestEmptySubobject)
226  SizeOfLargestEmptySubobject = EmptySize;
227  }
228 }
229 
230 bool
231 EmptySubobjectMap::CanPlaceSubobjectAtOffset(const CXXRecordDecl *RD,
232  CharUnits Offset) const {
233  // We only need to check empty bases.
234  if (!RD->isEmpty())
235  return true;
236 
237  EmptyClassOffsetsMapTy::const_iterator I = EmptyClassOffsets.find(Offset);
238  if (I == EmptyClassOffsets.end())
239  return true;
240 
241  const ClassVectorTy &Classes = I->second;
242  if (llvm::find(Classes, RD) == Classes.end())
243  return true;
244 
245  // There is already an empty class of the same type at this offset.
246  return false;
247 }
248 
249 void EmptySubobjectMap::AddSubobjectAtOffset(const CXXRecordDecl *RD,
250  CharUnits Offset) {
251  // We only care about empty bases.
252  if (!RD->isEmpty())
253  return;
254 
255  // If we have empty structures inside a union, we can assign both
256  // the same offset. Just avoid pushing them twice in the list.
257  ClassVectorTy &Classes = EmptyClassOffsets[Offset];
258  if (llvm::is_contained(Classes, RD))
259  return;
260 
261  Classes.push_back(RD);
262 
263  // Update the empty class offset.
264  if (Offset > MaxEmptyClassOffset)
265  MaxEmptyClassOffset = Offset;
266 }
267 
268 bool
269 EmptySubobjectMap::CanPlaceBaseSubobjectAtOffset(const BaseSubobjectInfo *Info,
270  CharUnits Offset) {
271  // We don't have to keep looking past the maximum offset that's known to
272  // contain an empty class.
273  if (!AnyEmptySubobjectsBeyondOffset(Offset))
274  return true;
275 
276  if (!CanPlaceSubobjectAtOffset(Info->Class, Offset))
277  return false;
278 
279  // Traverse all non-virtual bases.
280  const ASTRecordLayout &Layout = Context.getASTRecordLayout(Info->Class);
281  for (const BaseSubobjectInfo *Base : Info->Bases) {
282  if (Base->IsVirtual)
283  continue;
284 
285  CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base->Class);
286 
287  if (!CanPlaceBaseSubobjectAtOffset(Base, BaseOffset))
288  return false;
289  }
290 
291  if (Info->PrimaryVirtualBaseInfo) {
292  BaseSubobjectInfo *PrimaryVirtualBaseInfo = Info->PrimaryVirtualBaseInfo;
293 
294  if (Info == PrimaryVirtualBaseInfo->Derived) {
295  if (!CanPlaceBaseSubobjectAtOffset(PrimaryVirtualBaseInfo, Offset))
296  return false;
297  }
298  }
299 
300  // Traverse all member variables.
301  unsigned FieldNo = 0;
302  for (CXXRecordDecl::field_iterator I = Info->Class->field_begin(),
303  E = Info->Class->field_end(); I != E; ++I, ++FieldNo) {
304  if (I->isBitField())
305  continue;
306 
307  CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
308  if (!CanPlaceFieldSubobjectAtOffset(*I, FieldOffset))
309  return false;
310  }
311 
312  return true;
313 }
314 
315 void EmptySubobjectMap::UpdateEmptyBaseSubobjects(const BaseSubobjectInfo *Info,
316  CharUnits Offset,
317  bool PlacingEmptyBase) {
318  if (!PlacingEmptyBase && Offset >= SizeOfLargestEmptySubobject) {
319  // We know that the only empty subobjects that can conflict with empty
320  // subobject of non-empty bases, are empty bases that can be placed at
321  // offset zero. Because of this, we only need to keep track of empty base
322  // subobjects with offsets less than the size of the largest empty
323  // subobject for our class.
324  return;
325  }
326 
327  AddSubobjectAtOffset(Info->Class, Offset);
328 
329  // Traverse all non-virtual bases.
330  const ASTRecordLayout &Layout = Context.getASTRecordLayout(Info->Class);
331  for (const BaseSubobjectInfo *Base : Info->Bases) {
332  if (Base->IsVirtual)
333  continue;
334 
335  CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base->Class);
336  UpdateEmptyBaseSubobjects(Base, BaseOffset, PlacingEmptyBase);
337  }
338 
339  if (Info->PrimaryVirtualBaseInfo) {
340  BaseSubobjectInfo *PrimaryVirtualBaseInfo = Info->PrimaryVirtualBaseInfo;
341 
342  if (Info == PrimaryVirtualBaseInfo->Derived)
343  UpdateEmptyBaseSubobjects(PrimaryVirtualBaseInfo, Offset,
344  PlacingEmptyBase);
345  }
346 
347  // Traverse all member variables.
348  unsigned FieldNo = 0;
349  for (CXXRecordDecl::field_iterator I = Info->Class->field_begin(),
350  E = Info->Class->field_end(); I != E; ++I, ++FieldNo) {
351  if (I->isBitField())
352  continue;
353 
354  CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
355  UpdateEmptyFieldSubobjects(*I, FieldOffset, PlacingEmptyBase);
356  }
357 }
358 
359 bool EmptySubobjectMap::CanPlaceBaseAtOffset(const BaseSubobjectInfo *Info,
360  CharUnits Offset) {
361  // If we know this class doesn't have any empty subobjects we don't need to
362  // bother checking.
363  if (SizeOfLargestEmptySubobject.isZero())
364  return true;
365 
366  if (!CanPlaceBaseSubobjectAtOffset(Info, Offset))
367  return false;
368 
369  // We are able to place the base at this offset. Make sure to update the
370  // empty base subobject map.
371  UpdateEmptyBaseSubobjects(Info, Offset, Info->Class->isEmpty());
372  return true;
373 }
374 
375 bool
376 EmptySubobjectMap::CanPlaceFieldSubobjectAtOffset(const CXXRecordDecl *RD,
377  const CXXRecordDecl *Class,
378  CharUnits Offset) const {
379  // We don't have to keep looking past the maximum offset that's known to
380  // contain an empty class.
381  if (!AnyEmptySubobjectsBeyondOffset(Offset))
382  return true;
383 
384  if (!CanPlaceSubobjectAtOffset(RD, Offset))
385  return false;
386 
387  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
388 
389  // Traverse all non-virtual bases.
390  for (const CXXBaseSpecifier &Base : RD->bases()) {
391  if (Base.isVirtual())
392  continue;
393 
394  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
395 
396  CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(BaseDecl);
397  if (!CanPlaceFieldSubobjectAtOffset(BaseDecl, Class, BaseOffset))
398  return false;
399  }
400 
401  if (RD == Class) {
402  // This is the most derived class, traverse virtual bases as well.
403  for (const CXXBaseSpecifier &Base : RD->vbases()) {
404  const CXXRecordDecl *VBaseDecl = Base.getType()->getAsCXXRecordDecl();
405 
406  CharUnits VBaseOffset = Offset + Layout.getVBaseClassOffset(VBaseDecl);
407  if (!CanPlaceFieldSubobjectAtOffset(VBaseDecl, Class, VBaseOffset))
408  return false;
409  }
410  }
411 
412  // Traverse all member variables.
413  unsigned FieldNo = 0;
414  for (CXXRecordDecl::field_iterator I = RD->field_begin(), E = RD->field_end();
415  I != E; ++I, ++FieldNo) {
416  if (I->isBitField())
417  continue;
418 
419  CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
420 
421  if (!CanPlaceFieldSubobjectAtOffset(*I, FieldOffset))
422  return false;
423  }
424 
425  return true;
426 }
427 
428 bool
429 EmptySubobjectMap::CanPlaceFieldSubobjectAtOffset(const FieldDecl *FD,
430  CharUnits Offset) const {
431  // We don't have to keep looking past the maximum offset that's known to
432  // contain an empty class.
433  if (!AnyEmptySubobjectsBeyondOffset(Offset))
434  return true;
435 
436  QualType T = FD->getType();
437  if (const CXXRecordDecl *RD = T->getAsCXXRecordDecl())
438  return CanPlaceFieldSubobjectAtOffset(RD, RD, Offset);
439 
440  // If we have an array type we need to look at every element.
441  if (const ConstantArrayType *AT = Context.getAsConstantArrayType(T)) {
442  QualType ElemTy = Context.getBaseElementType(AT);
443  const RecordType *RT = ElemTy->getAs<RecordType>();
444  if (!RT)
445  return true;
446 
447  const CXXRecordDecl *RD = RT->getAsCXXRecordDecl();
448  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
449 
450  uint64_t NumElements = Context.getConstantArrayElementCount(AT);
451  CharUnits ElementOffset = Offset;
452  for (uint64_t I = 0; I != NumElements; ++I) {
453  // We don't have to keep looking past the maximum offset that's known to
454  // contain an empty class.
455  if (!AnyEmptySubobjectsBeyondOffset(ElementOffset))
456  return true;
457 
458  if (!CanPlaceFieldSubobjectAtOffset(RD, RD, ElementOffset))
459  return false;
460 
461  ElementOffset += Layout.getSize();
462  }
463  }
464 
465  return true;
466 }
467 
468 bool
469 EmptySubobjectMap::CanPlaceFieldAtOffset(const FieldDecl *FD,
470  CharUnits Offset) {
471  if (!CanPlaceFieldSubobjectAtOffset(FD, Offset))
472  return false;
473 
474  // We are able to place the member variable at this offset.
475  // Make sure to update the empty field subobject map.
476  UpdateEmptyFieldSubobjects(FD, Offset, FD->hasAttr<NoUniqueAddressAttr>());
477  return true;
478 }
479 
480 void EmptySubobjectMap::UpdateEmptyFieldSubobjects(
481  const CXXRecordDecl *RD, const CXXRecordDecl *Class, CharUnits Offset,
482  bool PlacingOverlappingField) {
483  // We know that the only empty subobjects that can conflict with empty
484  // field subobjects are subobjects of empty bases and potentially-overlapping
485  // fields that can be placed at offset zero. Because of this, we only need to
486  // keep track of empty field subobjects with offsets less than the size of
487  // the largest empty subobject for our class.
488  //
489  // (Proof: we will only consider placing a subobject at offset zero or at
490  // >= the current dsize. The only cases where the earlier subobject can be
491  // placed beyond the end of dsize is if it's an empty base or a
492  // potentially-overlapping field.)
493  if (!PlacingOverlappingField && Offset >= SizeOfLargestEmptySubobject)
494  return;
495 
496  AddSubobjectAtOffset(RD, Offset);
497 
498  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
499 
500  // Traverse all non-virtual bases.
501  for (const CXXBaseSpecifier &Base : RD->bases()) {
502  if (Base.isVirtual())
503  continue;
504 
505  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
506 
507  CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(BaseDecl);
508  UpdateEmptyFieldSubobjects(BaseDecl, Class, BaseOffset,
509  PlacingOverlappingField);
510  }
511 
512  if (RD == Class) {
513  // This is the most derived class, traverse virtual bases as well.
514  for (const CXXBaseSpecifier &Base : RD->vbases()) {
515  const CXXRecordDecl *VBaseDecl = Base.getType()->getAsCXXRecordDecl();
516 
517  CharUnits VBaseOffset = Offset + Layout.getVBaseClassOffset(VBaseDecl);
518  UpdateEmptyFieldSubobjects(VBaseDecl, Class, VBaseOffset,
519  PlacingOverlappingField);
520  }
521  }
522 
523  // Traverse all member variables.
524  unsigned FieldNo = 0;
525  for (CXXRecordDecl::field_iterator I = RD->field_begin(), E = RD->field_end();
526  I != E; ++I, ++FieldNo) {
527  if (I->isBitField())
528  continue;
529 
530  CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
531 
532  UpdateEmptyFieldSubobjects(*I, FieldOffset, PlacingOverlappingField);
533  }
534 }
535 
536 void EmptySubobjectMap::UpdateEmptyFieldSubobjects(
537  const FieldDecl *FD, CharUnits Offset, bool PlacingOverlappingField) {
538  QualType T = FD->getType();
539  if (const CXXRecordDecl *RD = T->getAsCXXRecordDecl()) {
540  UpdateEmptyFieldSubobjects(RD, RD, Offset, PlacingOverlappingField);
541  return;
542  }
543 
544  // If we have an array type we need to update every element.
545  if (const ConstantArrayType *AT = Context.getAsConstantArrayType(T)) {
546  QualType ElemTy = Context.getBaseElementType(AT);
547  const RecordType *RT = ElemTy->getAs<RecordType>();
548  if (!RT)
549  return;
550 
551  const CXXRecordDecl *RD = RT->getAsCXXRecordDecl();
552  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
553 
554  uint64_t NumElements = Context.getConstantArrayElementCount(AT);
555  CharUnits ElementOffset = Offset;
556 
557  for (uint64_t I = 0; I != NumElements; ++I) {
558  // We know that the only empty subobjects that can conflict with empty
559  // field subobjects are subobjects of empty bases that can be placed at
560  // offset zero. Because of this, we only need to keep track of empty field
561  // subobjects with offsets less than the size of the largest empty
562  // subobject for our class.
563  if (!PlacingOverlappingField &&
564  ElementOffset >= SizeOfLargestEmptySubobject)
565  return;
566 
567  UpdateEmptyFieldSubobjects(RD, RD, ElementOffset,
568  PlacingOverlappingField);
569  ElementOffset += Layout.getSize();
570  }
571  }
572 }
573 
574 typedef llvm::SmallPtrSet<const CXXRecordDecl*, 4> ClassSetTy;
575 
576 class ItaniumRecordLayoutBuilder {
577 protected:
578  // FIXME: Remove this and make the appropriate fields public.
579  friend class clang::ASTContext;
580 
581  const ASTContext &Context;
582 
583  EmptySubobjectMap *EmptySubobjects;
584 
585  /// Size - The current size of the record layout.
586  uint64_t Size;
587 
588  /// Alignment - The current alignment of the record layout.
589  CharUnits Alignment;
590 
591  /// The alignment if attribute packed is not used.
592  CharUnits UnpackedAlignment;
593 
594  /// \brief The maximum of the alignments of top-level members.
595  CharUnits UnadjustedAlignment;
596 
597  SmallVector<uint64_t, 16> FieldOffsets;
598 
599  /// Whether the external AST source has provided a layout for this
600  /// record.
601  unsigned UseExternalLayout : 1;
602 
603  /// Whether we need to infer alignment, even when we have an
604  /// externally-provided layout.
605  unsigned InferAlignment : 1;
606 
607  /// Packed - Whether the record is packed or not.
608  unsigned Packed : 1;
609 
610  unsigned IsUnion : 1;
611 
612  unsigned IsMac68kAlign : 1;
613 
614  unsigned IsMsStruct : 1;
615 
616  /// UnfilledBitsInLastUnit - If the last field laid out was a bitfield,
617  /// this contains the number of bits in the last unit that can be used for
618  /// an adjacent bitfield if necessary. The unit in question is usually
619  /// a byte, but larger units are used if IsMsStruct.
620  unsigned char UnfilledBitsInLastUnit;
621  /// LastBitfieldTypeSize - If IsMsStruct, represents the size of the type
622  /// of the previous field if it was a bitfield.
623  unsigned char LastBitfieldTypeSize;
624 
625  /// MaxFieldAlignment - The maximum allowed field alignment. This is set by
626  /// #pragma pack.
627  CharUnits MaxFieldAlignment;
628 
629  /// DataSize - The data size of the record being laid out.
630  uint64_t DataSize;
631 
632  CharUnits NonVirtualSize;
633  CharUnits NonVirtualAlignment;
634 
635  /// If we've laid out a field but not included its tail padding in Size yet,
636  /// this is the size up to the end of that field.
637  CharUnits PaddedFieldSize;
638 
639  /// PrimaryBase - the primary base class (if one exists) of the class
640  /// we're laying out.
641  const CXXRecordDecl *PrimaryBase;
642 
643  /// PrimaryBaseIsVirtual - Whether the primary base of the class we're laying
644  /// out is virtual.
645  bool PrimaryBaseIsVirtual;
646 
647  /// HasOwnVFPtr - Whether the class provides its own vtable/vftbl
648  /// pointer, as opposed to inheriting one from a primary base class.
649  bool HasOwnVFPtr;
650 
651  /// the flag of field offset changing due to packed attribute.
652  bool HasPackedField;
653 
654  typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsetsMapTy;
655 
656  /// Bases - base classes and their offsets in the record.
657  BaseOffsetsMapTy Bases;
658 
659  // VBases - virtual base classes and their offsets in the record.
661 
662  /// IndirectPrimaryBases - Virtual base classes, direct or indirect, that are
663  /// primary base classes for some other direct or indirect base class.
664  CXXIndirectPrimaryBaseSet IndirectPrimaryBases;
665 
666  /// FirstNearlyEmptyVBase - The first nearly empty virtual base class in
667  /// inheritance graph order. Used for determining the primary base class.
668  const CXXRecordDecl *FirstNearlyEmptyVBase;
669 
670  /// VisitedVirtualBases - A set of all the visited virtual bases, used to
671  /// avoid visiting virtual bases more than once.
672  llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBases;
673 
674  /// Valid if UseExternalLayout is true.
675  ExternalLayout External;
676 
677  ItaniumRecordLayoutBuilder(const ASTContext &Context,
678  EmptySubobjectMap *EmptySubobjects)
679  : Context(Context), EmptySubobjects(EmptySubobjects), Size(0),
680  Alignment(CharUnits::One()), UnpackedAlignment(CharUnits::One()),
681  UnadjustedAlignment(CharUnits::One()),
682  UseExternalLayout(false), InferAlignment(false), Packed(false),
683  IsUnion(false), IsMac68kAlign(false), IsMsStruct(false),
684  UnfilledBitsInLastUnit(0), LastBitfieldTypeSize(0),
685  MaxFieldAlignment(CharUnits::Zero()), DataSize(0),
686  NonVirtualSize(CharUnits::Zero()),
687  NonVirtualAlignment(CharUnits::One()),
688  PaddedFieldSize(CharUnits::Zero()), PrimaryBase(nullptr),
689  PrimaryBaseIsVirtual(false), HasOwnVFPtr(false),
690  HasPackedField(false), FirstNearlyEmptyVBase(nullptr) {}
691 
692  void Layout(const RecordDecl *D);
693  void Layout(const CXXRecordDecl *D);
694  void Layout(const ObjCInterfaceDecl *D);
695 
696  void LayoutFields(const RecordDecl *D);
697  void LayoutField(const FieldDecl *D, bool InsertExtraPadding);
698  void LayoutWideBitField(uint64_t FieldSize, uint64_t TypeSize,
699  bool FieldPacked, const FieldDecl *D);
700  void LayoutBitField(const FieldDecl *D);
701 
702  TargetCXXABI getCXXABI() const {
703  return Context.getTargetInfo().getCXXABI();
704  }
705 
706  /// BaseSubobjectInfoAllocator - Allocator for BaseSubobjectInfo objects.
707  llvm::SpecificBumpPtrAllocator<BaseSubobjectInfo> BaseSubobjectInfoAllocator;
708 
709  typedef llvm::DenseMap<const CXXRecordDecl *, BaseSubobjectInfo *>
710  BaseSubobjectInfoMapTy;
711 
712  /// VirtualBaseInfo - Map from all the (direct or indirect) virtual bases
713  /// of the class we're laying out to their base subobject info.
714  BaseSubobjectInfoMapTy VirtualBaseInfo;
715 
716  /// NonVirtualBaseInfo - Map from all the direct non-virtual bases of the
717  /// class we're laying out to their base subobject info.
718  BaseSubobjectInfoMapTy NonVirtualBaseInfo;
719 
720  /// ComputeBaseSubobjectInfo - Compute the base subobject information for the
721  /// bases of the given class.
722  void ComputeBaseSubobjectInfo(const CXXRecordDecl *RD);
723 
724  /// ComputeBaseSubobjectInfo - Compute the base subobject information for a
725  /// single class and all of its base classes.
726  BaseSubobjectInfo *ComputeBaseSubobjectInfo(const CXXRecordDecl *RD,
727  bool IsVirtual,
728  BaseSubobjectInfo *Derived);
729 
730  /// DeterminePrimaryBase - Determine the primary base of the given class.
731  void DeterminePrimaryBase(const CXXRecordDecl *RD);
732 
733  void SelectPrimaryVBase(const CXXRecordDecl *RD);
734 
735  void EnsureVTablePointerAlignment(CharUnits UnpackedBaseAlign);
736 
737  /// LayoutNonVirtualBases - Determines the primary base class (if any) and
738  /// lays it out. Will then proceed to lay out all non-virtual base clasess.
739  void LayoutNonVirtualBases(const CXXRecordDecl *RD);
740 
741  /// LayoutNonVirtualBase - Lays out a single non-virtual base.
742  void LayoutNonVirtualBase(const BaseSubobjectInfo *Base);
743 
744  void AddPrimaryVirtualBaseOffsets(const BaseSubobjectInfo *Info,
745  CharUnits Offset);
746 
747  /// LayoutVirtualBases - Lays out all the virtual bases.
748  void LayoutVirtualBases(const CXXRecordDecl *RD,
749  const CXXRecordDecl *MostDerivedClass);
750 
751  /// LayoutVirtualBase - Lays out a single virtual base.
752  void LayoutVirtualBase(const BaseSubobjectInfo *Base);
753 
754  /// LayoutBase - Will lay out a base and return the offset where it was
755  /// placed, in chars.
756  CharUnits LayoutBase(const BaseSubobjectInfo *Base);
757 
758  /// InitializeLayout - Initialize record layout for the given record decl.
759  void InitializeLayout(const Decl *D);
760 
761  /// FinishLayout - Finalize record layout. Adjust record size based on the
762  /// alignment.
763  void FinishLayout(const NamedDecl *D);
764 
765  void UpdateAlignment(CharUnits NewAlignment, CharUnits UnpackedNewAlignment);
766  void UpdateAlignment(CharUnits NewAlignment) {
767  UpdateAlignment(NewAlignment, NewAlignment);
768  }
769 
770  /// Retrieve the externally-supplied field offset for the given
771  /// field.
772  ///
773  /// \param Field The field whose offset is being queried.
774  /// \param ComputedOffset The offset that we've computed for this field.
775  uint64_t updateExternalFieldOffset(const FieldDecl *Field,
776  uint64_t ComputedOffset);
777 
778  void CheckFieldPadding(uint64_t Offset, uint64_t UnpaddedOffset,
779  uint64_t UnpackedOffset, unsigned UnpackedAlign,
780  bool isPacked, const FieldDecl *D);
781 
782  DiagnosticBuilder Diag(SourceLocation Loc, unsigned DiagID);
783 
784  CharUnits getSize() const {
785  assert(Size % Context.getCharWidth() == 0);
786  return Context.toCharUnitsFromBits(Size);
787  }
788  uint64_t getSizeInBits() const { return Size; }
789 
790  void setSize(CharUnits NewSize) { Size = Context.toBits(NewSize); }
791  void setSize(uint64_t NewSize) { Size = NewSize; }
792 
793  CharUnits getAligment() const { return Alignment; }
794 
795  CharUnits getDataSize() const {
796  assert(DataSize % Context.getCharWidth() == 0);
797  return Context.toCharUnitsFromBits(DataSize);
798  }
799  uint64_t getDataSizeInBits() const { return DataSize; }
800 
801  void setDataSize(CharUnits NewSize) { DataSize = Context.toBits(NewSize); }
802  void setDataSize(uint64_t NewSize) { DataSize = NewSize; }
803 
804  ItaniumRecordLayoutBuilder(const ItaniumRecordLayoutBuilder &) = delete;
805  void operator=(const ItaniumRecordLayoutBuilder &) = delete;
806 };
807 } // end anonymous namespace
808 
809 void ItaniumRecordLayoutBuilder::SelectPrimaryVBase(const CXXRecordDecl *RD) {
810  for (const auto &I : RD->bases()) {
811  assert(!I.getType()->isDependentType() &&
812  "Cannot layout class with dependent bases.");
813 
814  const CXXRecordDecl *Base = I.getType()->getAsCXXRecordDecl();
815 
816  // Check if this is a nearly empty virtual base.
817  if (I.isVirtual() && Context.isNearlyEmpty(Base)) {
818  // If it's not an indirect primary base, then we've found our primary
819  // base.
820  if (!IndirectPrimaryBases.count(Base)) {
821  PrimaryBase = Base;
822  PrimaryBaseIsVirtual = true;
823  return;
824  }
825 
826  // Is this the first nearly empty virtual base?
827  if (!FirstNearlyEmptyVBase)
828  FirstNearlyEmptyVBase = Base;
829  }
830 
831  SelectPrimaryVBase(Base);
832  if (PrimaryBase)
833  return;
834  }
835 }
836 
837 /// DeterminePrimaryBase - Determine the primary base of the given class.
838 void ItaniumRecordLayoutBuilder::DeterminePrimaryBase(const CXXRecordDecl *RD) {
839  // If the class isn't dynamic, it won't have a primary base.
840  if (!RD->isDynamicClass())
841  return;
842 
843  // Compute all the primary virtual bases for all of our direct and
844  // indirect bases, and record all their primary virtual base classes.
845  RD->getIndirectPrimaryBases(IndirectPrimaryBases);
846 
847  // If the record has a dynamic base class, attempt to choose a primary base
848  // class. It is the first (in direct base class order) non-virtual dynamic
849  // base class, if one exists.
850  for (const auto &I : RD->bases()) {
851  // Ignore virtual bases.
852  if (I.isVirtual())
853  continue;
854 
855  const CXXRecordDecl *Base = I.getType()->getAsCXXRecordDecl();
856 
857  if (Base->isDynamicClass()) {
858  // We found it.
859  PrimaryBase = Base;
860  PrimaryBaseIsVirtual = false;
861  return;
862  }
863  }
864 
865  // Under the Itanium ABI, if there is no non-virtual primary base class,
866  // try to compute the primary virtual base. The primary virtual base is
867  // the first nearly empty virtual base that is not an indirect primary
868  // virtual base class, if one exists.
869  if (RD->getNumVBases() != 0) {
870  SelectPrimaryVBase(RD);
871  if (PrimaryBase)
872  return;
873  }
874 
875  // Otherwise, it is the first indirect primary base class, if one exists.
876  if (FirstNearlyEmptyVBase) {
877  PrimaryBase = FirstNearlyEmptyVBase;
878  PrimaryBaseIsVirtual = true;
879  return;
880  }
881 
882  assert(!PrimaryBase && "Should not get here with a primary base!");
883 }
884 
885 BaseSubobjectInfo *ItaniumRecordLayoutBuilder::ComputeBaseSubobjectInfo(
886  const CXXRecordDecl *RD, bool IsVirtual, BaseSubobjectInfo *Derived) {
887  BaseSubobjectInfo *Info;
888 
889  if (IsVirtual) {
890  // Check if we already have info about this virtual base.
891  BaseSubobjectInfo *&InfoSlot = VirtualBaseInfo[RD];
892  if (InfoSlot) {
893  assert(InfoSlot->Class == RD && "Wrong class for virtual base info!");
894  return InfoSlot;
895  }
896 
897  // We don't, create it.
898  InfoSlot = new (BaseSubobjectInfoAllocator.Allocate()) BaseSubobjectInfo;
899  Info = InfoSlot;
900  } else {
901  Info = new (BaseSubobjectInfoAllocator.Allocate()) BaseSubobjectInfo;
902  }
903 
904  Info->Class = RD;
905  Info->IsVirtual = IsVirtual;
906  Info->Derived = nullptr;
907  Info->PrimaryVirtualBaseInfo = nullptr;
908 
909  const CXXRecordDecl *PrimaryVirtualBase = nullptr;
910  BaseSubobjectInfo *PrimaryVirtualBaseInfo = nullptr;
911 
912  // Check if this base has a primary virtual base.
913  if (RD->getNumVBases()) {
914  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
915  if (Layout.isPrimaryBaseVirtual()) {
916  // This base does have a primary virtual base.
917  PrimaryVirtualBase = Layout.getPrimaryBase();
918  assert(PrimaryVirtualBase && "Didn't have a primary virtual base!");
919 
920  // Now check if we have base subobject info about this primary base.
921  PrimaryVirtualBaseInfo = VirtualBaseInfo.lookup(PrimaryVirtualBase);
922 
923  if (PrimaryVirtualBaseInfo) {
924  if (PrimaryVirtualBaseInfo->Derived) {
925  // We did have info about this primary base, and it turns out that it
926  // has already been claimed as a primary virtual base for another
927  // base.
928  PrimaryVirtualBase = nullptr;
929  } else {
930  // We can claim this base as our primary base.
931  Info->PrimaryVirtualBaseInfo = PrimaryVirtualBaseInfo;
932  PrimaryVirtualBaseInfo->Derived = Info;
933  }
934  }
935  }
936  }
937 
938  // Now go through all direct bases.
939  for (const auto &I : RD->bases()) {
940  bool IsVirtual = I.isVirtual();
941 
942  const CXXRecordDecl *BaseDecl = I.getType()->getAsCXXRecordDecl();
943 
944  Info->Bases.push_back(ComputeBaseSubobjectInfo(BaseDecl, IsVirtual, Info));
945  }
946 
947  if (PrimaryVirtualBase && !PrimaryVirtualBaseInfo) {
948  // Traversing the bases must have created the base info for our primary
949  // virtual base.
950  PrimaryVirtualBaseInfo = VirtualBaseInfo.lookup(PrimaryVirtualBase);
951  assert(PrimaryVirtualBaseInfo &&
952  "Did not create a primary virtual base!");
953 
954  // Claim the primary virtual base as our primary virtual base.
955  Info->PrimaryVirtualBaseInfo = PrimaryVirtualBaseInfo;
956  PrimaryVirtualBaseInfo->Derived = Info;
957  }
958 
959  return Info;
960 }
961 
962 void ItaniumRecordLayoutBuilder::ComputeBaseSubobjectInfo(
963  const CXXRecordDecl *RD) {
964  for (const auto &I : RD->bases()) {
965  bool IsVirtual = I.isVirtual();
966 
967  const CXXRecordDecl *BaseDecl = I.getType()->getAsCXXRecordDecl();
968 
969  // Compute the base subobject info for this base.
970  BaseSubobjectInfo *Info = ComputeBaseSubobjectInfo(BaseDecl, IsVirtual,
971  nullptr);
972 
973  if (IsVirtual) {
974  // ComputeBaseInfo has already added this base for us.
975  assert(VirtualBaseInfo.count(BaseDecl) &&
976  "Did not add virtual base!");
977  } else {
978  // Add the base info to the map of non-virtual bases.
979  assert(!NonVirtualBaseInfo.count(BaseDecl) &&
980  "Non-virtual base already exists!");
981  NonVirtualBaseInfo.insert(std::make_pair(BaseDecl, Info));
982  }
983  }
984 }
985 
986 void ItaniumRecordLayoutBuilder::EnsureVTablePointerAlignment(
987  CharUnits UnpackedBaseAlign) {
988  CharUnits BaseAlign = Packed ? CharUnits::One() : UnpackedBaseAlign;
989 
990  // The maximum field alignment overrides base align.
991  if (!MaxFieldAlignment.isZero()) {
992  BaseAlign = std::min(BaseAlign, MaxFieldAlignment);
993  UnpackedBaseAlign = std::min(UnpackedBaseAlign, MaxFieldAlignment);
994  }
995 
996  // Round up the current record size to pointer alignment.
997  setSize(getSize().alignTo(BaseAlign));
998 
999  // Update the alignment.
1000  UpdateAlignment(BaseAlign, UnpackedBaseAlign);
1001 }
1002 
1003 void ItaniumRecordLayoutBuilder::LayoutNonVirtualBases(
1004  const CXXRecordDecl *RD) {
1005  // Then, determine the primary base class.
1006  DeterminePrimaryBase(RD);
1007 
1008  // Compute base subobject info.
1009  ComputeBaseSubobjectInfo(RD);
1010 
1011  // If we have a primary base class, lay it out.
1012  if (PrimaryBase) {
1013  if (PrimaryBaseIsVirtual) {
1014  // If the primary virtual base was a primary virtual base of some other
1015  // base class we'll have to steal it.
1016  BaseSubobjectInfo *PrimaryBaseInfo = VirtualBaseInfo.lookup(PrimaryBase);
1017  PrimaryBaseInfo->Derived = nullptr;
1018 
1019  // We have a virtual primary base, insert it as an indirect primary base.
1020  IndirectPrimaryBases.insert(PrimaryBase);
1021 
1022  assert(!VisitedVirtualBases.count(PrimaryBase) &&
1023  "vbase already visited!");
1024  VisitedVirtualBases.insert(PrimaryBase);
1025 
1026  LayoutVirtualBase(PrimaryBaseInfo);
1027  } else {
1028  BaseSubobjectInfo *PrimaryBaseInfo =
1029  NonVirtualBaseInfo.lookup(PrimaryBase);
1030  assert(PrimaryBaseInfo &&
1031  "Did not find base info for non-virtual primary base!");
1032 
1033  LayoutNonVirtualBase(PrimaryBaseInfo);
1034  }
1035 
1036  // If this class needs a vtable/vf-table and didn't get one from a
1037  // primary base, add it in now.
1038  } else if (RD->isDynamicClass()) {
1039  assert(DataSize == 0 && "Vtable pointer must be at offset zero!");
1040  CharUnits PtrWidth =
1041  Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
1042  CharUnits PtrAlign =
1043  Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerAlign(0));
1044  EnsureVTablePointerAlignment(PtrAlign);
1045  HasOwnVFPtr = true;
1046  setSize(getSize() + PtrWidth);
1047  setDataSize(getSize());
1048  }
1049 
1050  // Now lay out the non-virtual bases.
1051  for (const auto &I : RD->bases()) {
1052 
1053  // Ignore virtual bases.
1054  if (I.isVirtual())
1055  continue;
1056 
1057  const CXXRecordDecl *BaseDecl = I.getType()->getAsCXXRecordDecl();
1058 
1059  // Skip the primary base, because we've already laid it out. The
1060  // !PrimaryBaseIsVirtual check is required because we might have a
1061  // non-virtual base of the same type as a primary virtual base.
1062  if (BaseDecl == PrimaryBase && !PrimaryBaseIsVirtual)
1063  continue;
1064 
1065  // Lay out the base.
1066  BaseSubobjectInfo *BaseInfo = NonVirtualBaseInfo.lookup(BaseDecl);
1067  assert(BaseInfo && "Did not find base info for non-virtual base!");
1068 
1069  LayoutNonVirtualBase(BaseInfo);
1070  }
1071 }
1072 
1073 void ItaniumRecordLayoutBuilder::LayoutNonVirtualBase(
1074  const BaseSubobjectInfo *Base) {
1075  // Layout the base.
1076  CharUnits Offset = LayoutBase(Base);
1077 
1078  // Add its base class offset.
1079  assert(!Bases.count(Base->Class) && "base offset already exists!");
1080  Bases.insert(std::make_pair(Base->Class, Offset));
1081 
1082  AddPrimaryVirtualBaseOffsets(Base, Offset);
1083 }
1084 
1085 void ItaniumRecordLayoutBuilder::AddPrimaryVirtualBaseOffsets(
1086  const BaseSubobjectInfo *Info, CharUnits Offset) {
1087  // This base isn't interesting, it has no virtual bases.
1088  if (!Info->Class->getNumVBases())
1089  return;
1090 
1091  // First, check if we have a virtual primary base to add offsets for.
1092  if (Info->PrimaryVirtualBaseInfo) {
1093  assert(Info->PrimaryVirtualBaseInfo->IsVirtual &&
1094  "Primary virtual base is not virtual!");
1095  if (Info->PrimaryVirtualBaseInfo->Derived == Info) {
1096  // Add the offset.
1097  assert(!VBases.count(Info->PrimaryVirtualBaseInfo->Class) &&
1098  "primary vbase offset already exists!");
1099  VBases.insert(std::make_pair(Info->PrimaryVirtualBaseInfo->Class,
1100  ASTRecordLayout::VBaseInfo(Offset, false)));
1101 
1102  // Traverse the primary virtual base.
1103  AddPrimaryVirtualBaseOffsets(Info->PrimaryVirtualBaseInfo, Offset);
1104  }
1105  }
1106 
1107  // Now go through all direct non-virtual bases.
1108  const ASTRecordLayout &Layout = Context.getASTRecordLayout(Info->Class);
1109  for (const BaseSubobjectInfo *Base : Info->Bases) {
1110  if (Base->IsVirtual)
1111  continue;
1112 
1113  CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base->Class);
1114  AddPrimaryVirtualBaseOffsets(Base, BaseOffset);
1115  }
1116 }
1117 
1118 void ItaniumRecordLayoutBuilder::LayoutVirtualBases(
1119  const CXXRecordDecl *RD, const CXXRecordDecl *MostDerivedClass) {
1120  const CXXRecordDecl *PrimaryBase;
1121  bool PrimaryBaseIsVirtual;
1122 
1123  if (MostDerivedClass == RD) {
1124  PrimaryBase = this->PrimaryBase;
1125  PrimaryBaseIsVirtual = this->PrimaryBaseIsVirtual;
1126  } else {
1127  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1128  PrimaryBase = Layout.getPrimaryBase();
1129  PrimaryBaseIsVirtual = Layout.isPrimaryBaseVirtual();
1130  }
1131 
1132  for (const CXXBaseSpecifier &Base : RD->bases()) {
1133  assert(!Base.getType()->isDependentType() &&
1134  "Cannot layout class with dependent bases.");
1135 
1136  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
1137 
1138  if (Base.isVirtual()) {
1139  if (PrimaryBase != BaseDecl || !PrimaryBaseIsVirtual) {
1140  bool IndirectPrimaryBase = IndirectPrimaryBases.count(BaseDecl);
1141 
1142  // Only lay out the virtual base if it's not an indirect primary base.
1143  if (!IndirectPrimaryBase) {
1144  // Only visit virtual bases once.
1145  if (!VisitedVirtualBases.insert(BaseDecl).second)
1146  continue;
1147 
1148  const BaseSubobjectInfo *BaseInfo = VirtualBaseInfo.lookup(BaseDecl);
1149  assert(BaseInfo && "Did not find virtual base info!");
1150  LayoutVirtualBase(BaseInfo);
1151  }
1152  }
1153  }
1154 
1155  if (!BaseDecl->getNumVBases()) {
1156  // This base isn't interesting since it doesn't have any virtual bases.
1157  continue;
1158  }
1159 
1160  LayoutVirtualBases(BaseDecl, MostDerivedClass);
1161  }
1162 }
1163 
1164 void ItaniumRecordLayoutBuilder::LayoutVirtualBase(
1165  const BaseSubobjectInfo *Base) {
1166  assert(!Base->Derived && "Trying to lay out a primary virtual base!");
1167 
1168  // Layout the base.
1169  CharUnits Offset = LayoutBase(Base);
1170 
1171  // Add its base class offset.
1172  assert(!VBases.count(Base->Class) && "vbase offset already exists!");
1173  VBases.insert(std::make_pair(Base->Class,
1174  ASTRecordLayout::VBaseInfo(Offset, false)));
1175 
1176  AddPrimaryVirtualBaseOffsets(Base, Offset);
1177 }
1178 
1179 CharUnits
1180 ItaniumRecordLayoutBuilder::LayoutBase(const BaseSubobjectInfo *Base) {
1181  const ASTRecordLayout &Layout = Context.getASTRecordLayout(Base->Class);
1182 
1183 
1184  CharUnits Offset;
1185 
1186  // Query the external layout to see if it provides an offset.
1187  bool HasExternalLayout = false;
1188  if (UseExternalLayout) {
1189  // FIXME: This appears to be reversed.
1190  if (Base->IsVirtual)
1191  HasExternalLayout = External.getExternalNVBaseOffset(Base->Class, Offset);
1192  else
1193  HasExternalLayout = External.getExternalVBaseOffset(Base->Class, Offset);
1194  }
1195 
1196  // Clang <= 6 incorrectly applied the 'packed' attribute to base classes.
1197  // Per GCC's documentation, it only applies to non-static data members.
1198  CharUnits UnpackedBaseAlign = Layout.getNonVirtualAlignment();
1199  CharUnits BaseAlign =
1200  (Packed && ((Context.getLangOpts().getClangABICompat() <=
1202  Context.getTargetInfo().getTriple().isPS4()))
1203  ? CharUnits::One()
1204  : UnpackedBaseAlign;
1205 
1206  // If we have an empty base class, try to place it at offset 0.
1207  if (Base->Class->isEmpty() &&
1208  (!HasExternalLayout || Offset == CharUnits::Zero()) &&
1209  EmptySubobjects->CanPlaceBaseAtOffset(Base, CharUnits::Zero())) {
1210  setSize(std::max(getSize(), Layout.getSize()));
1211  UpdateAlignment(BaseAlign, UnpackedBaseAlign);
1212 
1213  return CharUnits::Zero();
1214  }
1215 
1216  // The maximum field alignment overrides base align.
1217  if (!MaxFieldAlignment.isZero()) {
1218  BaseAlign = std::min(BaseAlign, MaxFieldAlignment);
1219  UnpackedBaseAlign = std::min(UnpackedBaseAlign, MaxFieldAlignment);
1220  }
1221 
1222  if (!HasExternalLayout) {
1223  // Round up the current record size to the base's alignment boundary.
1224  Offset = getDataSize().alignTo(BaseAlign);
1225 
1226  // Try to place the base.
1227  while (!EmptySubobjects->CanPlaceBaseAtOffset(Base, Offset))
1228  Offset += BaseAlign;
1229  } else {
1230  bool Allowed = EmptySubobjects->CanPlaceBaseAtOffset(Base, Offset);
1231  (void)Allowed;
1232  assert(Allowed && "Base subobject externally placed at overlapping offset");
1233 
1234  if (InferAlignment && Offset < getDataSize().alignTo(BaseAlign)) {
1235  // The externally-supplied base offset is before the base offset we
1236  // computed. Assume that the structure is packed.
1237  Alignment = CharUnits::One();
1238  InferAlignment = false;
1239  }
1240  }
1241 
1242  if (!Base->Class->isEmpty()) {
1243  // Update the data size.
1244  setDataSize(Offset + Layout.getNonVirtualSize());
1245 
1246  setSize(std::max(getSize(), getDataSize()));
1247  } else
1248  setSize(std::max(getSize(), Offset + Layout.getSize()));
1249 
1250  // Remember max struct/class alignment.
1251  UpdateAlignment(BaseAlign, UnpackedBaseAlign);
1252 
1253  return Offset;
1254 }
1255 
1256 void ItaniumRecordLayoutBuilder::InitializeLayout(const Decl *D) {
1257  if (const RecordDecl *RD = dyn_cast<RecordDecl>(D)) {
1258  IsUnion = RD->isUnion();
1259  IsMsStruct = RD->isMsStruct(Context);
1260  }
1261 
1262  Packed = D->hasAttr<PackedAttr>();
1263 
1264  // Honor the default struct packing maximum alignment flag.
1265  if (unsigned DefaultMaxFieldAlignment = Context.getLangOpts().PackStruct) {
1266  MaxFieldAlignment = CharUnits::fromQuantity(DefaultMaxFieldAlignment);
1267  }
1268 
1269  // mac68k alignment supersedes maximum field alignment and attribute aligned,
1270  // and forces all structures to have 2-byte alignment. The IBM docs on it
1271  // allude to additional (more complicated) semantics, especially with regard
1272  // to bit-fields, but gcc appears not to follow that.
1273  if (D->hasAttr<AlignMac68kAttr>()) {
1274  IsMac68kAlign = true;
1275  MaxFieldAlignment = CharUnits::fromQuantity(2);
1276  Alignment = CharUnits::fromQuantity(2);
1277  } else {
1278  if (const MaxFieldAlignmentAttr *MFAA = D->getAttr<MaxFieldAlignmentAttr>())
1279  MaxFieldAlignment = Context.toCharUnitsFromBits(MFAA->getAlignment());
1280 
1281  if (unsigned MaxAlign = D->getMaxAlignment())
1282  UpdateAlignment(Context.toCharUnitsFromBits(MaxAlign));
1283  }
1284 
1285  // If there is an external AST source, ask it for the various offsets.
1286  if (const RecordDecl *RD = dyn_cast<RecordDecl>(D))
1287  if (ExternalASTSource *Source = Context.getExternalSource()) {
1288  UseExternalLayout = Source->layoutRecordType(
1289  RD, External.Size, External.Align, External.FieldOffsets,
1290  External.BaseOffsets, External.VirtualBaseOffsets);
1291 
1292  // Update based on external alignment.
1293  if (UseExternalLayout) {
1294  if (External.Align > 0) {
1295  Alignment = Context.toCharUnitsFromBits(External.Align);
1296  } else {
1297  // The external source didn't have alignment information; infer it.
1298  InferAlignment = true;
1299  }
1300  }
1301  }
1302 }
1303 
1304 void ItaniumRecordLayoutBuilder::Layout(const RecordDecl *D) {
1305  InitializeLayout(D);
1306  LayoutFields(D);
1307 
1308  // Finally, round the size of the total struct up to the alignment of the
1309  // struct itself.
1310  FinishLayout(D);
1311 }
1312 
1313 void ItaniumRecordLayoutBuilder::Layout(const CXXRecordDecl *RD) {
1314  InitializeLayout(RD);
1315 
1316  // Lay out the vtable and the non-virtual bases.
1317  LayoutNonVirtualBases(RD);
1318 
1319  LayoutFields(RD);
1320 
1321  NonVirtualSize = Context.toCharUnitsFromBits(
1322  llvm::alignTo(getSizeInBits(), Context.getTargetInfo().getCharAlign()));
1323  NonVirtualAlignment = Alignment;
1324 
1325  // Lay out the virtual bases and add the primary virtual base offsets.
1326  LayoutVirtualBases(RD, RD);
1327 
1328  // Finally, round the size of the total struct up to the alignment
1329  // of the struct itself.
1330  FinishLayout(RD);
1331 
1332 #ifndef NDEBUG
1333  // Check that we have base offsets for all bases.
1334  for (const CXXBaseSpecifier &Base : RD->bases()) {
1335  if (Base.isVirtual())
1336  continue;
1337 
1338  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
1339 
1340  assert(Bases.count(BaseDecl) && "Did not find base offset!");
1341  }
1342 
1343  // And all virtual bases.
1344  for (const CXXBaseSpecifier &Base : RD->vbases()) {
1345  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
1346 
1347  assert(VBases.count(BaseDecl) && "Did not find base offset!");
1348  }
1349 #endif
1350 }
1351 
1352 void ItaniumRecordLayoutBuilder::Layout(const ObjCInterfaceDecl *D) {
1353  if (ObjCInterfaceDecl *SD = D->getSuperClass()) {
1354  const ASTRecordLayout &SL = Context.getASTObjCInterfaceLayout(SD);
1355 
1356  UpdateAlignment(SL.getAlignment());
1357 
1358  // We start laying out ivars not at the end of the superclass
1359  // structure, but at the next byte following the last field.
1360  setDataSize(SL.getDataSize());
1361  setSize(getDataSize());
1362  }
1363 
1364  InitializeLayout(D);
1365  // Layout each ivar sequentially.
1366  for (const ObjCIvarDecl *IVD = D->all_declared_ivar_begin(); IVD;
1367  IVD = IVD->getNextIvar())
1368  LayoutField(IVD, false);
1369 
1370  // Finally, round the size of the total struct up to the alignment of the
1371  // struct itself.
1372  FinishLayout(D);
1373 }
1374 
1375 void ItaniumRecordLayoutBuilder::LayoutFields(const RecordDecl *D) {
1376  // Layout each field, for now, just sequentially, respecting alignment. In
1377  // the future, this will need to be tweakable by targets.
1378  bool InsertExtraPadding = D->mayInsertExtraPadding(/*EmitRemark=*/true);
1379  bool HasFlexibleArrayMember = D->hasFlexibleArrayMember();
1380  for (auto I = D->field_begin(), End = D->field_end(); I != End; ++I) {
1381  auto Next(I);
1382  ++Next;
1383  LayoutField(*I,
1384  InsertExtraPadding && (Next != End || !HasFlexibleArrayMember));
1385  }
1386 }
1387 
1388 // Rounds the specified size to have it a multiple of the char size.
1389 static uint64_t
1391  const ASTContext &Context) {
1392  uint64_t CharAlignment = Context.getTargetInfo().getCharAlign();
1393  return llvm::alignTo(Size, CharAlignment);
1394 }
1395 
1396 void ItaniumRecordLayoutBuilder::LayoutWideBitField(uint64_t FieldSize,
1397  uint64_t TypeSize,
1398  bool FieldPacked,
1399  const FieldDecl *D) {
1400  assert(Context.getLangOpts().CPlusPlus &&
1401  "Can only have wide bit-fields in C++!");
1402 
1403  // Itanium C++ ABI 2.4:
1404  // If sizeof(T)*8 < n, let T' be the largest integral POD type with
1405  // sizeof(T')*8 <= n.
1406 
1407  QualType IntegralPODTypes[] = {
1408  Context.UnsignedCharTy, Context.UnsignedShortTy, Context.UnsignedIntTy,
1409  Context.UnsignedLongTy, Context.UnsignedLongLongTy
1410  };
1411 
1412  QualType Type;
1413  for (const QualType &QT : IntegralPODTypes) {
1414  uint64_t Size = Context.getTypeSize(QT);
1415 
1416  if (Size > FieldSize)
1417  break;
1418 
1419  Type = QT;
1420  }
1421  assert(!Type.isNull() && "Did not find a type!");
1422 
1423  CharUnits TypeAlign = Context.getTypeAlignInChars(Type);
1424 
1425  // We're not going to use any of the unfilled bits in the last byte.
1426  UnfilledBitsInLastUnit = 0;
1427  LastBitfieldTypeSize = 0;
1428 
1429  uint64_t FieldOffset;
1430  uint64_t UnpaddedFieldOffset = getDataSizeInBits() - UnfilledBitsInLastUnit;
1431 
1432  if (IsUnion) {
1433  uint64_t RoundedFieldSize = roundUpSizeToCharAlignment(FieldSize,
1434  Context);
1435  setDataSize(std::max(getDataSizeInBits(), RoundedFieldSize));
1436  FieldOffset = 0;
1437  } else {
1438  // The bitfield is allocated starting at the next offset aligned
1439  // appropriately for T', with length n bits.
1440  FieldOffset = llvm::alignTo(getDataSizeInBits(), Context.toBits(TypeAlign));
1441 
1442  uint64_t NewSizeInBits = FieldOffset + FieldSize;
1443 
1444  setDataSize(
1445  llvm::alignTo(NewSizeInBits, Context.getTargetInfo().getCharAlign()));
1446  UnfilledBitsInLastUnit = getDataSizeInBits() - NewSizeInBits;
1447  }
1448 
1449  // Place this field at the current location.
1450  FieldOffsets.push_back(FieldOffset);
1451 
1452  CheckFieldPadding(FieldOffset, UnpaddedFieldOffset, FieldOffset,
1453  Context.toBits(TypeAlign), FieldPacked, D);
1454 
1455  // Update the size.
1456  setSize(std::max(getSizeInBits(), getDataSizeInBits()));
1457 
1458  // Remember max struct/class alignment.
1459  UpdateAlignment(TypeAlign);
1460 }
1461 
1462 void ItaniumRecordLayoutBuilder::LayoutBitField(const FieldDecl *D) {
1463  bool FieldPacked = Packed || D->hasAttr<PackedAttr>();
1464  uint64_t FieldSize = D->getBitWidthValue(Context);
1465  TypeInfo FieldInfo = Context.getTypeInfo(D->getType());
1466  uint64_t TypeSize = FieldInfo.Width;
1467  unsigned FieldAlign = FieldInfo.Align;
1468 
1469  // UnfilledBitsInLastUnit is the difference between the end of the
1470  // last allocated bitfield (i.e. the first bit offset available for
1471  // bitfields) and the end of the current data size in bits (i.e. the
1472  // first bit offset available for non-bitfields). The current data
1473  // size in bits is always a multiple of the char size; additionally,
1474  // for ms_struct records it's also a multiple of the
1475  // LastBitfieldTypeSize (if set).
1476 
1477  // The struct-layout algorithm is dictated by the platform ABI,
1478  // which in principle could use almost any rules it likes. In
1479  // practice, UNIXy targets tend to inherit the algorithm described
1480  // in the System V generic ABI. The basic bitfield layout rule in
1481  // System V is to place bitfields at the next available bit offset
1482  // where the entire bitfield would fit in an aligned storage unit of
1483  // the declared type; it's okay if an earlier or later non-bitfield
1484  // is allocated in the same storage unit. However, some targets
1485  // (those that !useBitFieldTypeAlignment(), e.g. ARM APCS) don't
1486  // require this storage unit to be aligned, and therefore always put
1487  // the bitfield at the next available bit offset.
1488 
1489  // ms_struct basically requests a complete replacement of the
1490  // platform ABI's struct-layout algorithm, with the high-level goal
1491  // of duplicating MSVC's layout. For non-bitfields, this follows
1492  // the standard algorithm. The basic bitfield layout rule is to
1493  // allocate an entire unit of the bitfield's declared type
1494  // (e.g. 'unsigned long'), then parcel it up among successive
1495  // bitfields whose declared types have the same size, making a new
1496  // unit as soon as the last can no longer store the whole value.
1497  // Since it completely replaces the platform ABI's algorithm,
1498  // settings like !useBitFieldTypeAlignment() do not apply.
1499 
1500  // A zero-width bitfield forces the use of a new storage unit for
1501  // later bitfields. In general, this occurs by rounding up the
1502  // current size of the struct as if the algorithm were about to
1503  // place a non-bitfield of the field's formal type. Usually this
1504  // does not change the alignment of the struct itself, but it does
1505  // on some targets (those that useZeroLengthBitfieldAlignment(),
1506  // e.g. ARM). In ms_struct layout, zero-width bitfields are
1507  // ignored unless they follow a non-zero-width bitfield.
1508 
1509  // A field alignment restriction (e.g. from #pragma pack) or
1510  // specification (e.g. from __attribute__((aligned))) changes the
1511  // formal alignment of the field. For System V, this alters the
1512  // required alignment of the notional storage unit that must contain
1513  // the bitfield. For ms_struct, this only affects the placement of
1514  // new storage units. In both cases, the effect of #pragma pack is
1515  // ignored on zero-width bitfields.
1516 
1517  // On System V, a packed field (e.g. from #pragma pack or
1518  // __attribute__((packed))) always uses the next available bit
1519  // offset.
1520 
1521  // In an ms_struct struct, the alignment of a fundamental type is
1522  // always equal to its size. This is necessary in order to mimic
1523  // the i386 alignment rules on targets which might not fully align
1524  // all types (e.g. Darwin PPC32, where alignof(long long) == 4).
1525 
1526  // First, some simple bookkeeping to perform for ms_struct structs.
1527  if (IsMsStruct) {
1528  // The field alignment for integer types is always the size.
1529  FieldAlign = TypeSize;
1530 
1531  // If the previous field was not a bitfield, or was a bitfield
1532  // with a different storage unit size, or if this field doesn't fit into
1533  // the current storage unit, we're done with that storage unit.
1534  if (LastBitfieldTypeSize != TypeSize ||
1535  UnfilledBitsInLastUnit < FieldSize) {
1536  // Also, ignore zero-length bitfields after non-bitfields.
1537  if (!LastBitfieldTypeSize && !FieldSize)
1538  FieldAlign = 1;
1539 
1540  UnfilledBitsInLastUnit = 0;
1541  LastBitfieldTypeSize = 0;
1542  }
1543  }
1544 
1545  // If the field is wider than its declared type, it follows
1546  // different rules in all cases.
1547  if (FieldSize > TypeSize) {
1548  LayoutWideBitField(FieldSize, TypeSize, FieldPacked, D);
1549  return;
1550  }
1551 
1552  // Compute the next available bit offset.
1553  uint64_t FieldOffset =
1554  IsUnion ? 0 : (getDataSizeInBits() - UnfilledBitsInLastUnit);
1555 
1556  // Handle targets that don't honor bitfield type alignment.
1557  if (!IsMsStruct && !Context.getTargetInfo().useBitFieldTypeAlignment()) {
1558  // Some such targets do honor it on zero-width bitfields.
1559  if (FieldSize == 0 &&
1561  // The alignment to round up to is the max of the field's natural
1562  // alignment and a target-specific fixed value (sometimes zero).
1563  unsigned ZeroLengthBitfieldBoundary =
1565  FieldAlign = std::max(FieldAlign, ZeroLengthBitfieldBoundary);
1566 
1567  // If that doesn't apply, just ignore the field alignment.
1568  } else {
1569  FieldAlign = 1;
1570  }
1571  }
1572 
1573  // Remember the alignment we would have used if the field were not packed.
1574  unsigned UnpackedFieldAlign = FieldAlign;
1575 
1576  // Ignore the field alignment if the field is packed unless it has zero-size.
1577  if (!IsMsStruct && FieldPacked && FieldSize != 0)
1578  FieldAlign = 1;
1579 
1580  // But, if there's an 'aligned' attribute on the field, honor that.
1581  unsigned ExplicitFieldAlign = D->getMaxAlignment();
1582  if (ExplicitFieldAlign) {
1583  FieldAlign = std::max(FieldAlign, ExplicitFieldAlign);
1584  UnpackedFieldAlign = std::max(UnpackedFieldAlign, ExplicitFieldAlign);
1585  }
1586 
1587  // But, if there's a #pragma pack in play, that takes precedent over
1588  // even the 'aligned' attribute, for non-zero-width bitfields.
1589  unsigned MaxFieldAlignmentInBits = Context.toBits(MaxFieldAlignment);
1590  if (!MaxFieldAlignment.isZero() && FieldSize) {
1591  UnpackedFieldAlign = std::min(UnpackedFieldAlign, MaxFieldAlignmentInBits);
1592  if (FieldPacked)
1593  FieldAlign = UnpackedFieldAlign;
1594  else
1595  FieldAlign = std::min(FieldAlign, MaxFieldAlignmentInBits);
1596  }
1597 
1598  // But, ms_struct just ignores all of that in unions, even explicit
1599  // alignment attributes.
1600  if (IsMsStruct && IsUnion) {
1601  FieldAlign = UnpackedFieldAlign = 1;
1602  }
1603 
1604  // For purposes of diagnostics, we're going to simultaneously
1605  // compute the field offsets that we would have used if we weren't
1606  // adding any alignment padding or if the field weren't packed.
1607  uint64_t UnpaddedFieldOffset = FieldOffset;
1608  uint64_t UnpackedFieldOffset = FieldOffset;
1609 
1610  // Check if we need to add padding to fit the bitfield within an
1611  // allocation unit with the right size and alignment. The rules are
1612  // somewhat different here for ms_struct structs.
1613  if (IsMsStruct) {
1614  // If it's not a zero-width bitfield, and we can fit the bitfield
1615  // into the active storage unit (and we haven't already decided to
1616  // start a new storage unit), just do so, regardless of any other
1617  // other consideration. Otherwise, round up to the right alignment.
1618  if (FieldSize == 0 || FieldSize > UnfilledBitsInLastUnit) {
1619  FieldOffset = llvm::alignTo(FieldOffset, FieldAlign);
1620  UnpackedFieldOffset =
1621  llvm::alignTo(UnpackedFieldOffset, UnpackedFieldAlign);
1622  UnfilledBitsInLastUnit = 0;
1623  }
1624 
1625  } else {
1626  // #pragma pack, with any value, suppresses the insertion of padding.
1627  bool AllowPadding = MaxFieldAlignment.isZero();
1628 
1629  // Compute the real offset.
1630  if (FieldSize == 0 ||
1631  (AllowPadding &&
1632  (FieldOffset & (FieldAlign-1)) + FieldSize > TypeSize)) {
1633  FieldOffset = llvm::alignTo(FieldOffset, FieldAlign);
1634  } else if (ExplicitFieldAlign &&
1635  (MaxFieldAlignmentInBits == 0 ||
1636  ExplicitFieldAlign <= MaxFieldAlignmentInBits) &&
1638  // TODO: figure it out what needs to be done on targets that don't honor
1639  // bit-field type alignment like ARM APCS ABI.
1640  FieldOffset = llvm::alignTo(FieldOffset, ExplicitFieldAlign);
1641  }
1642 
1643  // Repeat the computation for diagnostic purposes.
1644  if (FieldSize == 0 ||
1645  (AllowPadding &&
1646  (UnpackedFieldOffset & (UnpackedFieldAlign-1)) + FieldSize > TypeSize))
1647  UnpackedFieldOffset =
1648  llvm::alignTo(UnpackedFieldOffset, UnpackedFieldAlign);
1649  else if (ExplicitFieldAlign &&
1650  (MaxFieldAlignmentInBits == 0 ||
1651  ExplicitFieldAlign <= MaxFieldAlignmentInBits) &&
1653  UnpackedFieldOffset =
1654  llvm::alignTo(UnpackedFieldOffset, ExplicitFieldAlign);
1655  }
1656 
1657  // If we're using external layout, give the external layout a chance
1658  // to override this information.
1659  if (UseExternalLayout)
1660  FieldOffset = updateExternalFieldOffset(D, FieldOffset);
1661 
1662  // Okay, place the bitfield at the calculated offset.
1663  FieldOffsets.push_back(FieldOffset);
1664 
1665  // Bookkeeping:
1666 
1667  // Anonymous members don't affect the overall record alignment,
1668  // except on targets where they do.
1669  if (!IsMsStruct &&
1671  !D->getIdentifier())
1672  FieldAlign = UnpackedFieldAlign = 1;
1673 
1674  // Diagnose differences in layout due to padding or packing.
1675  if (!UseExternalLayout)
1676  CheckFieldPadding(FieldOffset, UnpaddedFieldOffset, UnpackedFieldOffset,
1677  UnpackedFieldAlign, FieldPacked, D);
1678 
1679  // Update DataSize to include the last byte containing (part of) the bitfield.
1680 
1681  // For unions, this is just a max operation, as usual.
1682  if (IsUnion) {
1683  // For ms_struct, allocate the entire storage unit --- unless this
1684  // is a zero-width bitfield, in which case just use a size of 1.
1685  uint64_t RoundedFieldSize;
1686  if (IsMsStruct) {
1687  RoundedFieldSize =
1688  (FieldSize ? TypeSize : Context.getTargetInfo().getCharWidth());
1689 
1690  // Otherwise, allocate just the number of bytes required to store
1691  // the bitfield.
1692  } else {
1693  RoundedFieldSize = roundUpSizeToCharAlignment(FieldSize, Context);
1694  }
1695  setDataSize(std::max(getDataSizeInBits(), RoundedFieldSize));
1696 
1697  // For non-zero-width bitfields in ms_struct structs, allocate a new
1698  // storage unit if necessary.
1699  } else if (IsMsStruct && FieldSize) {
1700  // We should have cleared UnfilledBitsInLastUnit in every case
1701  // where we changed storage units.
1702  if (!UnfilledBitsInLastUnit) {
1703  setDataSize(FieldOffset + TypeSize);
1704  UnfilledBitsInLastUnit = TypeSize;
1705  }
1706  UnfilledBitsInLastUnit -= FieldSize;
1707  LastBitfieldTypeSize = TypeSize;
1708 
1709  // Otherwise, bump the data size up to include the bitfield,
1710  // including padding up to char alignment, and then remember how
1711  // bits we didn't use.
1712  } else {
1713  uint64_t NewSizeInBits = FieldOffset + FieldSize;
1714  uint64_t CharAlignment = Context.getTargetInfo().getCharAlign();
1715  setDataSize(llvm::alignTo(NewSizeInBits, CharAlignment));
1716  UnfilledBitsInLastUnit = getDataSizeInBits() - NewSizeInBits;
1717 
1718  // The only time we can get here for an ms_struct is if this is a
1719  // zero-width bitfield, which doesn't count as anything for the
1720  // purposes of unfilled bits.
1721  LastBitfieldTypeSize = 0;
1722  }
1723 
1724  // Update the size.
1725  setSize(std::max(getSizeInBits(), getDataSizeInBits()));
1726 
1727  // Remember max struct/class alignment.
1728  UnadjustedAlignment =
1729  std::max(UnadjustedAlignment, Context.toCharUnitsFromBits(FieldAlign));
1730  UpdateAlignment(Context.toCharUnitsFromBits(FieldAlign),
1731  Context.toCharUnitsFromBits(UnpackedFieldAlign));
1732 }
1733 
1734 void ItaniumRecordLayoutBuilder::LayoutField(const FieldDecl *D,
1735  bool InsertExtraPadding) {
1736  if (D->isBitField()) {
1737  LayoutBitField(D);
1738  return;
1739  }
1740 
1741  uint64_t UnpaddedFieldOffset = getDataSizeInBits() - UnfilledBitsInLastUnit;
1742 
1743  // Reset the unfilled bits.
1744  UnfilledBitsInLastUnit = 0;
1745  LastBitfieldTypeSize = 0;
1746 
1747  auto *FieldClass = D->getType()->getAsCXXRecordDecl();
1748  bool PotentiallyOverlapping = D->hasAttr<NoUniqueAddressAttr>() && FieldClass;
1749  bool IsOverlappingEmptyField = PotentiallyOverlapping && FieldClass->isEmpty();
1750  bool FieldPacked = Packed || D->hasAttr<PackedAttr>();
1751 
1752  CharUnits FieldOffset = (IsUnion || IsOverlappingEmptyField)
1753  ? CharUnits::Zero()
1754  : getDataSize();
1755  CharUnits FieldSize;
1756  CharUnits FieldAlign;
1757  // The amount of this class's dsize occupied by the field.
1758  // This is equal to FieldSize unless we're permitted to pack
1759  // into the field's tail padding.
1760  CharUnits EffectiveFieldSize;
1761 
1762  if (D->getType()->isIncompleteArrayType()) {
1763  // This is a flexible array member; we can't directly
1764  // query getTypeInfo about these, so we figure it out here.
1765  // Flexible array members don't have any size, but they
1766  // have to be aligned appropriately for their element type.
1767  EffectiveFieldSize = FieldSize = CharUnits::Zero();
1768  const ArrayType* ATy = Context.getAsArrayType(D->getType());
1769  FieldAlign = Context.getTypeAlignInChars(ATy->getElementType());
1770  } else if (const ReferenceType *RT = D->getType()->getAs<ReferenceType>()) {
1771  unsigned AS = Context.getTargetAddressSpace(RT->getPointeeType());
1772  EffectiveFieldSize = FieldSize =
1773  Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(AS));
1774  FieldAlign =
1775  Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerAlign(AS));
1776  } else {
1777  std::pair<CharUnits, CharUnits> FieldInfo =
1778  Context.getTypeInfoInChars(D->getType());
1779  EffectiveFieldSize = FieldSize = FieldInfo.first;
1780  FieldAlign = FieldInfo.second;
1781 
1782  // A potentially-overlapping field occupies its dsize or nvsize, whichever
1783  // is larger.
1784  if (PotentiallyOverlapping) {
1785  const ASTRecordLayout &Layout = Context.getASTRecordLayout(FieldClass);
1786  EffectiveFieldSize =
1787  std::max(Layout.getNonVirtualSize(), Layout.getDataSize());
1788  }
1789 
1790  if (IsMsStruct) {
1791  // If MS bitfield layout is required, figure out what type is being
1792  // laid out and align the field to the width of that type.
1793 
1794  // Resolve all typedefs down to their base type and round up the field
1795  // alignment if necessary.
1796  QualType T = Context.getBaseElementType(D->getType());
1797  if (const BuiltinType *BTy = T->getAs<BuiltinType>()) {
1798  CharUnits TypeSize = Context.getTypeSizeInChars(BTy);
1799 
1800  if (!llvm::isPowerOf2_64(TypeSize.getQuantity())) {
1801  assert(
1802  !Context.getTargetInfo().getTriple().isWindowsMSVCEnvironment() &&
1803  "Non PowerOf2 size in MSVC mode");
1804  // Base types with sizes that aren't a power of two don't work
1805  // with the layout rules for MS structs. This isn't an issue in
1806  // MSVC itself since there are no such base data types there.
1807  // On e.g. x86_32 mingw and linux, long double is 12 bytes though.
1808  // Any structs involving that data type obviously can't be ABI
1809  // compatible with MSVC regardless of how it is laid out.
1810 
1811  // Since ms_struct can be mass enabled (via a pragma or via the
1812  // -mms-bitfields command line parameter), this can trigger for
1813  // structs that don't actually need MSVC compatibility, so we
1814  // need to be able to sidestep the ms_struct layout for these types.
1815 
1816  // Since the combination of -mms-bitfields together with structs
1817  // like max_align_t (which contains a long double) for mingw is
1818  // quite comon (and GCC handles it silently), just handle it
1819  // silently there. For other targets that have ms_struct enabled
1820  // (most probably via a pragma or attribute), trigger a diagnostic
1821  // that defaults to an error.
1822  if (!Context.getTargetInfo().getTriple().isWindowsGNUEnvironment())
1823  Diag(D->getLocation(), diag::warn_npot_ms_struct);
1824  }
1825  if (TypeSize > FieldAlign &&
1826  llvm::isPowerOf2_64(TypeSize.getQuantity()))
1827  FieldAlign = TypeSize;
1828  }
1829  }
1830  }
1831 
1832  // The align if the field is not packed. This is to check if the attribute
1833  // was unnecessary (-Wpacked).
1834  CharUnits UnpackedFieldAlign = FieldAlign;
1835  CharUnits UnpackedFieldOffset = FieldOffset;
1836 
1837  if (FieldPacked)
1838  FieldAlign = CharUnits::One();
1839  CharUnits MaxAlignmentInChars =
1840  Context.toCharUnitsFromBits(D->getMaxAlignment());
1841  FieldAlign = std::max(FieldAlign, MaxAlignmentInChars);
1842  UnpackedFieldAlign = std::max(UnpackedFieldAlign, MaxAlignmentInChars);
1843 
1844  // The maximum field alignment overrides the aligned attribute.
1845  if (!MaxFieldAlignment.isZero()) {
1846  FieldAlign = std::min(FieldAlign, MaxFieldAlignment);
1847  UnpackedFieldAlign = std::min(UnpackedFieldAlign, MaxFieldAlignment);
1848  }
1849 
1850  // Round up the current record size to the field's alignment boundary.
1851  FieldOffset = FieldOffset.alignTo(FieldAlign);
1852  UnpackedFieldOffset = UnpackedFieldOffset.alignTo(UnpackedFieldAlign);
1853 
1854  if (UseExternalLayout) {
1855  FieldOffset = Context.toCharUnitsFromBits(
1856  updateExternalFieldOffset(D, Context.toBits(FieldOffset)));
1857 
1858  if (!IsUnion && EmptySubobjects) {
1859  // Record the fact that we're placing a field at this offset.
1860  bool Allowed = EmptySubobjects->CanPlaceFieldAtOffset(D, FieldOffset);
1861  (void)Allowed;
1862  assert(Allowed && "Externally-placed field cannot be placed here");
1863  }
1864  } else {
1865  if (!IsUnion && EmptySubobjects) {
1866  // Check if we can place the field at this offset.
1867  while (!EmptySubobjects->CanPlaceFieldAtOffset(D, FieldOffset)) {
1868  // We couldn't place the field at the offset. Try again at a new offset.
1869  // We try offset 0 (for an empty field) and then dsize(C) onwards.
1870  if (FieldOffset == CharUnits::Zero() &&
1871  getDataSize() != CharUnits::Zero())
1872  FieldOffset = getDataSize().alignTo(FieldAlign);
1873  else
1874  FieldOffset += FieldAlign;
1875  }
1876  }
1877  }
1878 
1879  // Place this field at the current location.
1880  FieldOffsets.push_back(Context.toBits(FieldOffset));
1881 
1882  if (!UseExternalLayout)
1883  CheckFieldPadding(Context.toBits(FieldOffset), UnpaddedFieldOffset,
1884  Context.toBits(UnpackedFieldOffset),
1885  Context.toBits(UnpackedFieldAlign), FieldPacked, D);
1886 
1887  if (InsertExtraPadding) {
1888  CharUnits ASanAlignment = CharUnits::fromQuantity(8);
1889  CharUnits ExtraSizeForAsan = ASanAlignment;
1890  if (FieldSize % ASanAlignment)
1891  ExtraSizeForAsan +=
1892  ASanAlignment - CharUnits::fromQuantity(FieldSize % ASanAlignment);
1893  EffectiveFieldSize = FieldSize = FieldSize + ExtraSizeForAsan;
1894  }
1895 
1896  // Reserve space for this field.
1897  if (!IsOverlappingEmptyField) {
1898  uint64_t EffectiveFieldSizeInBits = Context.toBits(EffectiveFieldSize);
1899  if (IsUnion)
1900  setDataSize(std::max(getDataSizeInBits(), EffectiveFieldSizeInBits));
1901  else
1902  setDataSize(FieldOffset + EffectiveFieldSize);
1903 
1904  PaddedFieldSize = std::max(PaddedFieldSize, FieldOffset + FieldSize);
1905  setSize(std::max(getSizeInBits(), getDataSizeInBits()));
1906  } else {
1907  setSize(std::max(getSizeInBits(),
1908  (uint64_t)Context.toBits(FieldOffset + FieldSize)));
1909  }
1910 
1911  // Remember max struct/class alignment.
1912  UnadjustedAlignment = std::max(UnadjustedAlignment, FieldAlign);
1913  UpdateAlignment(FieldAlign, UnpackedFieldAlign);
1914 }
1915 
1916 void ItaniumRecordLayoutBuilder::FinishLayout(const NamedDecl *D) {
1917  // In C++, records cannot be of size 0.
1918  if (Context.getLangOpts().CPlusPlus && getSizeInBits() == 0) {
1919  if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D)) {
1920  // Compatibility with gcc requires a class (pod or non-pod)
1921  // which is not empty but of size 0; such as having fields of
1922  // array of zero-length, remains of Size 0
1923  if (RD->isEmpty())
1924  setSize(CharUnits::One());
1925  }
1926  else
1927  setSize(CharUnits::One());
1928  }
1929 
1930  // If we have any remaining field tail padding, include that in the overall
1931  // size.
1932  setSize(std::max(getSizeInBits(), (uint64_t)Context.toBits(PaddedFieldSize)));
1933 
1934  // Finally, round the size of the record up to the alignment of the
1935  // record itself.
1936  uint64_t UnpaddedSize = getSizeInBits() - UnfilledBitsInLastUnit;
1937  uint64_t UnpackedSizeInBits =
1938  llvm::alignTo(getSizeInBits(), Context.toBits(UnpackedAlignment));
1939  uint64_t RoundedSize =
1940  llvm::alignTo(getSizeInBits(), Context.toBits(Alignment));
1941 
1942  if (UseExternalLayout) {
1943  // If we're inferring alignment, and the external size is smaller than
1944  // our size after we've rounded up to alignment, conservatively set the
1945  // alignment to 1.
1946  if (InferAlignment && External.Size < RoundedSize) {
1947  Alignment = CharUnits::One();
1948  InferAlignment = false;
1949  }
1950  setSize(External.Size);
1951  return;
1952  }
1953 
1954  // Set the size to the final size.
1955  setSize(RoundedSize);
1956 
1957  unsigned CharBitNum = Context.getTargetInfo().getCharWidth();
1958  if (const RecordDecl *RD = dyn_cast<RecordDecl>(D)) {
1959  // Warn if padding was introduced to the struct/class/union.
1960  if (getSizeInBits() > UnpaddedSize) {
1961  unsigned PadSize = getSizeInBits() - UnpaddedSize;
1962  bool InBits = true;
1963  if (PadSize % CharBitNum == 0) {
1964  PadSize = PadSize / CharBitNum;
1965  InBits = false;
1966  }
1967  Diag(RD->getLocation(), diag::warn_padded_struct_size)
1968  << Context.getTypeDeclType(RD)
1969  << PadSize
1970  << (InBits ? 1 : 0); // (byte|bit)
1971  }
1972 
1973  // Warn if we packed it unnecessarily, when the unpacked alignment is not
1974  // greater than the one after packing, the size in bits doesn't change and
1975  // the offset of each field is identical.
1976  if (Packed && UnpackedAlignment <= Alignment &&
1977  UnpackedSizeInBits == getSizeInBits() && !HasPackedField)
1978  Diag(D->getLocation(), diag::warn_unnecessary_packed)
1979  << Context.getTypeDeclType(RD);
1980  }
1981 }
1982 
1983 void ItaniumRecordLayoutBuilder::UpdateAlignment(
1984  CharUnits NewAlignment, CharUnits UnpackedNewAlignment) {
1985  // The alignment is not modified when using 'mac68k' alignment or when
1986  // we have an externally-supplied layout that also provides overall alignment.
1987  if (IsMac68kAlign || (UseExternalLayout && !InferAlignment))
1988  return;
1989 
1990  if (NewAlignment > Alignment) {
1991  assert(llvm::isPowerOf2_64(NewAlignment.getQuantity()) &&
1992  "Alignment not a power of 2");
1993  Alignment = NewAlignment;
1994  }
1995 
1996  if (UnpackedNewAlignment > UnpackedAlignment) {
1997  assert(llvm::isPowerOf2_64(UnpackedNewAlignment.getQuantity()) &&
1998  "Alignment not a power of 2");
1999  UnpackedAlignment = UnpackedNewAlignment;
2000  }
2001 }
2002 
2003 uint64_t
2004 ItaniumRecordLayoutBuilder::updateExternalFieldOffset(const FieldDecl *Field,
2005  uint64_t ComputedOffset) {
2006  uint64_t ExternalFieldOffset = External.getExternalFieldOffset(Field);
2007 
2008  if (InferAlignment && ExternalFieldOffset < ComputedOffset) {
2009  // The externally-supplied field offset is before the field offset we
2010  // computed. Assume that the structure is packed.
2011  Alignment = CharUnits::One();
2012  InferAlignment = false;
2013  }
2014 
2015  // Use the externally-supplied field offset.
2016  return ExternalFieldOffset;
2017 }
2018 
2019 /// Get diagnostic %select index for tag kind for
2020 /// field padding diagnostic message.
2021 /// WARNING: Indexes apply to particular diagnostics only!
2022 ///
2023 /// \returns diagnostic %select index.
2025  switch (Tag) {
2026  case TTK_Struct: return 0;
2027  case TTK_Interface: return 1;
2028  case TTK_Class: return 2;
2029  default: llvm_unreachable("Invalid tag kind for field padding diagnostic!");
2030  }
2031 }
2032 
2033 void ItaniumRecordLayoutBuilder::CheckFieldPadding(
2034  uint64_t Offset, uint64_t UnpaddedOffset, uint64_t UnpackedOffset,
2035  unsigned UnpackedAlign, bool isPacked, const FieldDecl *D) {
2036  // We let objc ivars without warning, objc interfaces generally are not used
2037  // for padding tricks.
2038  if (isa<ObjCIvarDecl>(D))
2039  return;
2040 
2041  // Don't warn about structs created without a SourceLocation. This can
2042  // be done by clients of the AST, such as codegen.
2043  if (D->getLocation().isInvalid())
2044  return;
2045 
2046  unsigned CharBitNum = Context.getTargetInfo().getCharWidth();
2047 
2048  // Warn if padding was introduced to the struct/class.
2049  if (!IsUnion && Offset > UnpaddedOffset) {
2050  unsigned PadSize = Offset - UnpaddedOffset;
2051  bool InBits = true;
2052  if (PadSize % CharBitNum == 0) {
2053  PadSize = PadSize / CharBitNum;
2054  InBits = false;
2055  }
2056  if (D->getIdentifier())
2057  Diag(D->getLocation(), diag::warn_padded_struct_field)
2059  << Context.getTypeDeclType(D->getParent())
2060  << PadSize
2061  << (InBits ? 1 : 0) // (byte|bit)
2062  << D->getIdentifier();
2063  else
2064  Diag(D->getLocation(), diag::warn_padded_struct_anon_field)
2066  << Context.getTypeDeclType(D->getParent())
2067  << PadSize
2068  << (InBits ? 1 : 0); // (byte|bit)
2069  }
2070  if (isPacked && Offset != UnpackedOffset) {
2071  HasPackedField = true;
2072  }
2073 }
2074 
2076  const CXXRecordDecl *RD) {
2077  // If a class isn't polymorphic it doesn't have a key function.
2078  if (!RD->isPolymorphic())
2079  return nullptr;
2080 
2081  // A class that is not externally visible doesn't have a key function. (Or
2082  // at least, there's no point to assigning a key function to such a class;
2083  // this doesn't affect the ABI.)
2084  if (!RD->isExternallyVisible())
2085  return nullptr;
2086 
2087  // Template instantiations don't have key functions per Itanium C++ ABI 5.2.6.
2088  // Same behavior as GCC.
2090  if (TSK == TSK_ImplicitInstantiation ||
2093  return nullptr;
2094 
2095  bool allowInlineFunctions =
2097 
2098  for (const CXXMethodDecl *MD : RD->methods()) {
2099  if (!MD->isVirtual())
2100  continue;
2101 
2102  if (MD->isPure())
2103  continue;
2104 
2105  // Ignore implicit member functions, they are always marked as inline, but
2106  // they don't have a body until they're defined.
2107  if (MD->isImplicit())
2108  continue;
2109 
2110  if (MD->isInlineSpecified())
2111  continue;
2112 
2113  if (MD->hasInlineBody())
2114  continue;
2115 
2116  // Ignore inline deleted or defaulted functions.
2117  if (!MD->isUserProvided())
2118  continue;
2119 
2120  // In certain ABIs, ignore functions with out-of-line inline definitions.
2121  if (!allowInlineFunctions) {
2122  const FunctionDecl *Def;
2123  if (MD->hasBody(Def) && Def->isInlineSpecified())
2124  continue;
2125  }
2126 
2127  if (Context.getLangOpts().CUDA) {
2128  // While compiler may see key method in this TU, during CUDA
2129  // compilation we should ignore methods that are not accessible
2130  // on this side of compilation.
2131  if (Context.getLangOpts().CUDAIsDevice) {
2132  // In device mode ignore methods without __device__ attribute.
2133  if (!MD->hasAttr<CUDADeviceAttr>())
2134  continue;
2135  } else {
2136  // In host mode ignore __device__-only methods.
2137  if (!MD->hasAttr<CUDAHostAttr>() && MD->hasAttr<CUDADeviceAttr>())
2138  continue;
2139  }
2140  }
2141 
2142  // If the key function is dllimport but the class isn't, then the class has
2143  // no key function. The DLL that exports the key function won't export the
2144  // vtable in this case.
2145  if (MD->hasAttr<DLLImportAttr>() && !RD->hasAttr<DLLImportAttr>())
2146  return nullptr;
2147 
2148  // We found it.
2149  return MD;
2150  }
2151 
2152  return nullptr;
2153 }
2154 
2156  unsigned DiagID) {
2157  return Context.getDiagnostics().Report(Loc, DiagID);
2158 }
2159 
2160 /// Does the target C++ ABI require us to skip over the tail-padding
2161 /// of the given class (considering it as a base class) when allocating
2162 /// objects?
2163 static bool mustSkipTailPadding(TargetCXXABI ABI, const CXXRecordDecl *RD) {
2164  switch (ABI.getTailPaddingUseRules()) {
2166  return false;
2167 
2169  // FIXME: To the extent that this is meant to cover the Itanium ABI
2170  // rules, we should implement the restrictions about over-sized
2171  // bitfields:
2172  //
2173  // http://itanium-cxx-abi.github.io/cxx-abi/abi.html#POD :
2174  // In general, a type is considered a POD for the purposes of
2175  // layout if it is a POD type (in the sense of ISO C++
2176  // [basic.types]). However, a POD-struct or POD-union (in the
2177  // sense of ISO C++ [class]) with a bitfield member whose
2178  // declared width is wider than the declared type of the
2179  // bitfield is not a POD for the purpose of layout. Similarly,
2180  // an array type is not a POD for the purpose of layout if the
2181  // element type of the array is not a POD for the purpose of
2182  // layout.
2183  //
2184  // Where references to the ISO C++ are made in this paragraph,
2185  // the Technical Corrigendum 1 version of the standard is
2186  // intended.
2187  return RD->isPOD();
2188 
2190  // This is equivalent to RD->getTypeForDecl().isCXX11PODType(),
2191  // but with a lot of abstraction penalty stripped off. This does
2192  // assume that these properties are set correctly even in C++98
2193  // mode; fortunately, that is true because we want to assign
2194  // consistently semantics to the type-traits intrinsics (or at
2195  // least as many of them as possible).
2196  return RD->isTrivial() && RD->isCXX11StandardLayout();
2197  }
2198 
2199  llvm_unreachable("bad tail-padding use kind");
2200 }
2201 
2202 static bool isMsLayout(const ASTContext &Context) {
2203  return Context.getTargetInfo().getCXXABI().isMicrosoft();
2204 }
2205 
2206 // This section contains an implementation of struct layout that is, up to the
2207 // included tests, compatible with cl.exe (2013). The layout produced is
2208 // significantly different than those produced by the Itanium ABI. Here we note
2209 // the most important differences.
2210 //
2211 // * The alignment of bitfields in unions is ignored when computing the
2212 // alignment of the union.
2213 // * The existence of zero-width bitfield that occurs after anything other than
2214 // a non-zero length bitfield is ignored.
2215 // * There is no explicit primary base for the purposes of layout. All bases
2216 // with vfptrs are laid out first, followed by all bases without vfptrs.
2217 // * The Itanium equivalent vtable pointers are split into a vfptr (virtual
2218 // function pointer) and a vbptr (virtual base pointer). They can each be
2219 // shared with a, non-virtual bases. These bases need not be the same. vfptrs
2220 // always occur at offset 0. vbptrs can occur at an arbitrary offset and are
2221 // placed after the lexicographically last non-virtual base. This placement
2222 // is always before fields but can be in the middle of the non-virtual bases
2223 // due to the two-pass layout scheme for non-virtual-bases.
2224 // * Virtual bases sometimes require a 'vtordisp' field that is laid out before
2225 // the virtual base and is used in conjunction with virtual overrides during
2226 // construction and destruction. This is always a 4 byte value and is used as
2227 // an alternative to constructor vtables.
2228 // * vtordisps are allocated in a block of memory with size and alignment equal
2229 // to the alignment of the completed structure (before applying __declspec(
2230 // align())). The vtordisp always occur at the end of the allocation block,
2231 // immediately prior to the virtual base.
2232 // * vfptrs are injected after all bases and fields have been laid out. In
2233 // order to guarantee proper alignment of all fields, the vfptr injection
2234 // pushes all bases and fields back by the alignment imposed by those bases
2235 // and fields. This can potentially add a significant amount of padding.
2236 // vfptrs are always injected at offset 0.
2237 // * vbptrs are injected after all bases and fields have been laid out. In
2238 // order to guarantee proper alignment of all fields, the vfptr injection
2239 // pushes all bases and fields back by the alignment imposed by those bases
2240 // and fields. This can potentially add a significant amount of padding.
2241 // vbptrs are injected immediately after the last non-virtual base as
2242 // lexicographically ordered in the code. If this site isn't pointer aligned
2243 // the vbptr is placed at the next properly aligned location. Enough padding
2244 // is added to guarantee a fit.
2245 // * The last zero sized non-virtual base can be placed at the end of the
2246 // struct (potentially aliasing another object), or may alias with the first
2247 // field, even if they are of the same type.
2248 // * The last zero size virtual base may be placed at the end of the struct
2249 // potentially aliasing another object.
2250 // * The ABI attempts to avoid aliasing of zero sized bases by adding padding
2251 // between bases or vbases with specific properties. The criteria for
2252 // additional padding between two bases is that the first base is zero sized
2253 // or ends with a zero sized subobject and the second base is zero sized or
2254 // trails with a zero sized base or field (sharing of vfptrs can reorder the
2255 // layout of the so the leading base is not always the first one declared).
2256 // This rule does take into account fields that are not records, so padding
2257 // will occur even if the last field is, e.g. an int. The padding added for
2258 // bases is 1 byte. The padding added between vbases depends on the alignment
2259 // of the object but is at least 4 bytes (in both 32 and 64 bit modes).
2260 // * There is no concept of non-virtual alignment, non-virtual alignment and
2261 // alignment are always identical.
2262 // * There is a distinction between alignment and required alignment.
2263 // __declspec(align) changes the required alignment of a struct. This
2264 // alignment is _always_ obeyed, even in the presence of #pragma pack. A
2265 // record inherits required alignment from all of its fields and bases.
2266 // * __declspec(align) on bitfields has the effect of changing the bitfield's
2267 // alignment instead of its required alignment. This is the only known way
2268 // to make the alignment of a struct bigger than 8. Interestingly enough
2269 // this alignment is also immune to the effects of #pragma pack and can be
2270 // used to create structures with large alignment under #pragma pack.
2271 // However, because it does not impact required alignment, such a structure,
2272 // when used as a field or base, will not be aligned if #pragma pack is
2273 // still active at the time of use.
2274 //
2275 // Known incompatibilities:
2276 // * all: #pragma pack between fields in a record
2277 // * 2010 and back: If the last field in a record is a bitfield, every object
2278 // laid out after the record will have extra padding inserted before it. The
2279 // extra padding will have size equal to the size of the storage class of the
2280 // bitfield. 0 sized bitfields don't exhibit this behavior and the extra
2281 // padding can be avoided by adding a 0 sized bitfield after the non-zero-
2282 // sized bitfield.
2283 // * 2012 and back: In 64-bit mode, if the alignment of a record is 16 or
2284 // greater due to __declspec(align()) then a second layout phase occurs after
2285 // The locations of the vf and vb pointers are known. This layout phase
2286 // suffers from the "last field is a bitfield" bug in 2010 and results in
2287 // _every_ field getting padding put in front of it, potentially including the
2288 // vfptr, leaving the vfprt at a non-zero location which results in a fault if
2289 // anything tries to read the vftbl. The second layout phase also treats
2290 // bitfields as separate entities and gives them each storage rather than
2291 // packing them. Additionally, because this phase appears to perform a
2292 // (an unstable) sort on the members before laying them out and because merged
2293 // bitfields have the same address, the bitfields end up in whatever order
2294 // the sort left them in, a behavior we could never hope to replicate.
2295 
2296 namespace {
2297 struct MicrosoftRecordLayoutBuilder {
2298  struct ElementInfo {
2299  CharUnits Size;
2300  CharUnits Alignment;
2301  };
2302  typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsetsMapTy;
2303  MicrosoftRecordLayoutBuilder(const ASTContext &Context) : Context(Context) {}
2304 private:
2305  MicrosoftRecordLayoutBuilder(const MicrosoftRecordLayoutBuilder &) = delete;
2306  void operator=(const MicrosoftRecordLayoutBuilder &) = delete;
2307 public:
2308  void layout(const RecordDecl *RD);
2309  void cxxLayout(const CXXRecordDecl *RD);
2310  /// Initializes size and alignment and honors some flags.
2311  void initializeLayout(const RecordDecl *RD);
2312  /// Initialized C++ layout, compute alignment and virtual alignment and
2313  /// existence of vfptrs and vbptrs. Alignment is needed before the vfptr is
2314  /// laid out.
2315  void initializeCXXLayout(const CXXRecordDecl *RD);
2316  void layoutNonVirtualBases(const CXXRecordDecl *RD);
2317  void layoutNonVirtualBase(const CXXRecordDecl *RD,
2318  const CXXRecordDecl *BaseDecl,
2319  const ASTRecordLayout &BaseLayout,
2320  const ASTRecordLayout *&PreviousBaseLayout);
2321  void injectVFPtr(const CXXRecordDecl *RD);
2322  void injectVBPtr(const CXXRecordDecl *RD);
2323  /// Lays out the fields of the record. Also rounds size up to
2324  /// alignment.
2325  void layoutFields(const RecordDecl *RD);
2326  void layoutField(const FieldDecl *FD);
2327  void layoutBitField(const FieldDecl *FD);
2328  /// Lays out a single zero-width bit-field in the record and handles
2329  /// special cases associated with zero-width bit-fields.
2330  void layoutZeroWidthBitField(const FieldDecl *FD);
2331  void layoutVirtualBases(const CXXRecordDecl *RD);
2332  void finalizeLayout(const RecordDecl *RD);
2333  /// Gets the size and alignment of a base taking pragma pack and
2334  /// __declspec(align) into account.
2335  ElementInfo getAdjustedElementInfo(const ASTRecordLayout &Layout);
2336  /// Gets the size and alignment of a field taking pragma pack and
2337  /// __declspec(align) into account. It also updates RequiredAlignment as a
2338  /// side effect because it is most convenient to do so here.
2339  ElementInfo getAdjustedElementInfo(const FieldDecl *FD);
2340  /// Places a field at an offset in CharUnits.
2341  void placeFieldAtOffset(CharUnits FieldOffset) {
2342  FieldOffsets.push_back(Context.toBits(FieldOffset));
2343  }
2344  /// Places a bitfield at a bit offset.
2345  void placeFieldAtBitOffset(uint64_t FieldOffset) {
2346  FieldOffsets.push_back(FieldOffset);
2347  }
2348  /// Compute the set of virtual bases for which vtordisps are required.
2349  void computeVtorDispSet(
2350  llvm::SmallPtrSetImpl<const CXXRecordDecl *> &HasVtorDispSet,
2351  const CXXRecordDecl *RD) const;
2352  const ASTContext &Context;
2353  /// The size of the record being laid out.
2354  CharUnits Size;
2355  /// The non-virtual size of the record layout.
2356  CharUnits NonVirtualSize;
2357  /// The data size of the record layout.
2358  CharUnits DataSize;
2359  /// The current alignment of the record layout.
2360  CharUnits Alignment;
2361  /// The maximum allowed field alignment. This is set by #pragma pack.
2362  CharUnits MaxFieldAlignment;
2363  /// The alignment that this record must obey. This is imposed by
2364  /// __declspec(align()) on the record itself or one of its fields or bases.
2365  CharUnits RequiredAlignment;
2366  /// The size of the allocation of the currently active bitfield.
2367  /// This value isn't meaningful unless LastFieldIsNonZeroWidthBitfield
2368  /// is true.
2369  CharUnits CurrentBitfieldSize;
2370  /// Offset to the virtual base table pointer (if one exists).
2371  CharUnits VBPtrOffset;
2372  /// Minimum record size possible.
2373  CharUnits MinEmptyStructSize;
2374  /// The size and alignment info of a pointer.
2375  ElementInfo PointerInfo;
2376  /// The primary base class (if one exists).
2377  const CXXRecordDecl *PrimaryBase;
2378  /// The class we share our vb-pointer with.
2379  const CXXRecordDecl *SharedVBPtrBase;
2380  /// The collection of field offsets.
2381  SmallVector<uint64_t, 16> FieldOffsets;
2382  /// Base classes and their offsets in the record.
2383  BaseOffsetsMapTy Bases;
2384  /// virtual base classes and their offsets in the record.
2386  /// The number of remaining bits in our last bitfield allocation.
2387  /// This value isn't meaningful unless LastFieldIsNonZeroWidthBitfield is
2388  /// true.
2389  unsigned RemainingBitsInField;
2390  bool IsUnion : 1;
2391  /// True if the last field laid out was a bitfield and was not 0
2392  /// width.
2393  bool LastFieldIsNonZeroWidthBitfield : 1;
2394  /// True if the class has its own vftable pointer.
2395  bool HasOwnVFPtr : 1;
2396  /// True if the class has a vbtable pointer.
2397  bool HasVBPtr : 1;
2398  /// True if the last sub-object within the type is zero sized or the
2399  /// object itself is zero sized. This *does not* count members that are not
2400  /// records. Only used for MS-ABI.
2401  bool EndsWithZeroSizedObject : 1;
2402  /// True if this class is zero sized or first base is zero sized or
2403  /// has this property. Only used for MS-ABI.
2404  bool LeadsWithZeroSizedBase : 1;
2405 
2406  /// True if the external AST source provided a layout for this record.
2407  bool UseExternalLayout : 1;
2408 
2409  /// The layout provided by the external AST source. Only active if
2410  /// UseExternalLayout is true.
2411  ExternalLayout External;
2412 };
2413 } // namespace
2414 
2415 MicrosoftRecordLayoutBuilder::ElementInfo
2416 MicrosoftRecordLayoutBuilder::getAdjustedElementInfo(
2417  const ASTRecordLayout &Layout) {
2418  ElementInfo Info;
2419  Info.Alignment = Layout.getAlignment();
2420  // Respect pragma pack.
2421  if (!MaxFieldAlignment.isZero())
2422  Info.Alignment = std::min(Info.Alignment, MaxFieldAlignment);
2423  // Track zero-sized subobjects here where it's already available.
2424  EndsWithZeroSizedObject = Layout.endsWithZeroSizedObject();
2425  // Respect required alignment, this is necessary because we may have adjusted
2426  // the alignment in the case of pragam pack. Note that the required alignment
2427  // doesn't actually apply to the struct alignment at this point.
2428  Alignment = std::max(Alignment, Info.Alignment);
2429  RequiredAlignment = std::max(RequiredAlignment, Layout.getRequiredAlignment());
2430  Info.Alignment = std::max(Info.Alignment, Layout.getRequiredAlignment());
2431  Info.Size = Layout.getNonVirtualSize();
2432  return Info;
2433 }
2434 
2435 MicrosoftRecordLayoutBuilder::ElementInfo
2436 MicrosoftRecordLayoutBuilder::getAdjustedElementInfo(
2437  const FieldDecl *FD) {
2438  // Get the alignment of the field type's natural alignment, ignore any
2439  // alignment attributes.
2440  ElementInfo Info;
2441  std::tie(Info.Size, Info.Alignment) =
2443  // Respect align attributes on the field.
2444  CharUnits FieldRequiredAlignment =
2445  Context.toCharUnitsFromBits(FD->getMaxAlignment());
2446  // Respect align attributes on the type.
2447  if (Context.isAlignmentRequired(FD->getType()))
2448  FieldRequiredAlignment = std::max(
2449  Context.getTypeAlignInChars(FD->getType()), FieldRequiredAlignment);
2450  // Respect attributes applied to subobjects of the field.
2451  if (FD->isBitField())
2452  // For some reason __declspec align impacts alignment rather than required
2453  // alignment when it is applied to bitfields.
2454  Info.Alignment = std::max(Info.Alignment, FieldRequiredAlignment);
2455  else {
2456  if (auto RT =
2458  auto const &Layout = Context.getASTRecordLayout(RT->getDecl());
2459  EndsWithZeroSizedObject = Layout.endsWithZeroSizedObject();
2460  FieldRequiredAlignment = std::max(FieldRequiredAlignment,
2461  Layout.getRequiredAlignment());
2462  }
2463  // Capture required alignment as a side-effect.
2464  RequiredAlignment = std::max(RequiredAlignment, FieldRequiredAlignment);
2465  }
2466  // Respect pragma pack, attribute pack and declspec align
2467  if (!MaxFieldAlignment.isZero())
2468  Info.Alignment = std::min(Info.Alignment, MaxFieldAlignment);
2469  if (FD->hasAttr<PackedAttr>())
2470  Info.Alignment = CharUnits::One();
2471  Info.Alignment = std::max(Info.Alignment, FieldRequiredAlignment);
2472  return Info;
2473 }
2474 
2475 void MicrosoftRecordLayoutBuilder::layout(const RecordDecl *RD) {
2476  // For C record layout, zero-sized records always have size 4.
2477  MinEmptyStructSize = CharUnits::fromQuantity(4);
2478  initializeLayout(RD);
2479  layoutFields(RD);
2480  DataSize = Size = Size.alignTo(Alignment);
2481  RequiredAlignment = std::max(
2482  RequiredAlignment, Context.toCharUnitsFromBits(RD->getMaxAlignment()));
2483  finalizeLayout(RD);
2484 }
2485 
2486 void MicrosoftRecordLayoutBuilder::cxxLayout(const CXXRecordDecl *RD) {
2487  // The C++ standard says that empty structs have size 1.
2488  MinEmptyStructSize = CharUnits::One();
2489  initializeLayout(RD);
2490  initializeCXXLayout(RD);
2491  layoutNonVirtualBases(RD);
2492  layoutFields(RD);
2493  injectVBPtr(RD);
2494  injectVFPtr(RD);
2495  if (HasOwnVFPtr || (HasVBPtr && !SharedVBPtrBase))
2496  Alignment = std::max(Alignment, PointerInfo.Alignment);
2497  auto RoundingAlignment = Alignment;
2498  if (!MaxFieldAlignment.isZero())
2499  RoundingAlignment = std::min(RoundingAlignment, MaxFieldAlignment);
2500  if (!UseExternalLayout)
2501  Size = Size.alignTo(RoundingAlignment);
2502  NonVirtualSize = Size;
2503  RequiredAlignment = std::max(
2504  RequiredAlignment, Context.toCharUnitsFromBits(RD->getMaxAlignment()));
2505  layoutVirtualBases(RD);
2506  finalizeLayout(RD);
2507 }
2508 
2509 void MicrosoftRecordLayoutBuilder::initializeLayout(const RecordDecl *RD) {
2510  IsUnion = RD->isUnion();
2511  Size = CharUnits::Zero();
2512  Alignment = CharUnits::One();
2513  // In 64-bit mode we always perform an alignment step after laying out vbases.
2514  // In 32-bit mode we do not. The check to see if we need to perform alignment
2515  // checks the RequiredAlignment field and performs alignment if it isn't 0.
2516  RequiredAlignment = Context.getTargetInfo().getTriple().isArch64Bit()
2517  ? CharUnits::One()
2518  : CharUnits::Zero();
2519  // Compute the maximum field alignment.
2520  MaxFieldAlignment = CharUnits::Zero();
2521  // Honor the default struct packing maximum alignment flag.
2522  if (unsigned DefaultMaxFieldAlignment = Context.getLangOpts().PackStruct)
2523  MaxFieldAlignment = CharUnits::fromQuantity(DefaultMaxFieldAlignment);
2524  // Honor the packing attribute. The MS-ABI ignores pragma pack if its larger
2525  // than the pointer size.
2526  if (const MaxFieldAlignmentAttr *MFAA = RD->getAttr<MaxFieldAlignmentAttr>()){
2527  unsigned PackedAlignment = MFAA->getAlignment();
2528  if (PackedAlignment <= Context.getTargetInfo().getPointerWidth(0))
2529  MaxFieldAlignment = Context.toCharUnitsFromBits(PackedAlignment);
2530  }
2531  // Packed attribute forces max field alignment to be 1.
2532  if (RD->hasAttr<PackedAttr>())
2533  MaxFieldAlignment = CharUnits::One();
2534 
2535  // Try to respect the external layout if present.
2536  UseExternalLayout = false;
2537  if (ExternalASTSource *Source = Context.getExternalSource())
2538  UseExternalLayout = Source->layoutRecordType(
2539  RD, External.Size, External.Align, External.FieldOffsets,
2540  External.BaseOffsets, External.VirtualBaseOffsets);
2541 }
2542 
2543 void
2544 MicrosoftRecordLayoutBuilder::initializeCXXLayout(const CXXRecordDecl *RD) {
2545  EndsWithZeroSizedObject = false;
2546  LeadsWithZeroSizedBase = false;
2547  HasOwnVFPtr = false;
2548  HasVBPtr = false;
2549  PrimaryBase = nullptr;
2550  SharedVBPtrBase = nullptr;
2551  // Calculate pointer size and alignment. These are used for vfptr and vbprt
2552  // injection.
2553  PointerInfo.Size =
2554  Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
2555  PointerInfo.Alignment =
2556  Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerAlign(0));
2557  // Respect pragma pack.
2558  if (!MaxFieldAlignment.isZero())
2559  PointerInfo.Alignment = std::min(PointerInfo.Alignment, MaxFieldAlignment);
2560 }
2561 
2562 void
2563 MicrosoftRecordLayoutBuilder::layoutNonVirtualBases(const CXXRecordDecl *RD) {
2564  // The MS-ABI lays out all bases that contain leading vfptrs before it lays
2565  // out any bases that do not contain vfptrs. We implement this as two passes
2566  // over the bases. This approach guarantees that the primary base is laid out
2567  // first. We use these passes to calculate some additional aggregated
2568  // information about the bases, such as required alignment and the presence of
2569  // zero sized members.
2570  const ASTRecordLayout *PreviousBaseLayout = nullptr;
2571  // Iterate through the bases and lay out the non-virtual ones.
2572  for (const CXXBaseSpecifier &Base : RD->bases()) {
2573  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2574  const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2575  // Mark and skip virtual bases.
2576  if (Base.isVirtual()) {
2577  HasVBPtr = true;
2578  continue;
2579  }
2580  // Check for a base to share a VBPtr with.
2581  if (!SharedVBPtrBase && BaseLayout.hasVBPtr()) {
2582  SharedVBPtrBase = BaseDecl;
2583  HasVBPtr = true;
2584  }
2585  // Only lay out bases with extendable VFPtrs on the first pass.
2586  if (!BaseLayout.hasExtendableVFPtr())
2587  continue;
2588  // If we don't have a primary base, this one qualifies.
2589  if (!PrimaryBase) {
2590  PrimaryBase = BaseDecl;
2591  LeadsWithZeroSizedBase = BaseLayout.leadsWithZeroSizedBase();
2592  }
2593  // Lay out the base.
2594  layoutNonVirtualBase(RD, BaseDecl, BaseLayout, PreviousBaseLayout);
2595  }
2596  // Figure out if we need a fresh VFPtr for this class.
2597  if (!PrimaryBase && RD->isDynamicClass())
2599  e = RD->method_end();
2600  !HasOwnVFPtr && i != e; ++i)
2601  HasOwnVFPtr = i->isVirtual() && i->size_overridden_methods() == 0;
2602  // If we don't have a primary base then we have a leading object that could
2603  // itself lead with a zero-sized object, something we track.
2604  bool CheckLeadingLayout = !PrimaryBase;
2605  // Iterate through the bases and lay out the non-virtual ones.
2606  for (const CXXBaseSpecifier &Base : RD->bases()) {
2607  if (Base.isVirtual())
2608  continue;
2609  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2610  const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2611  // Only lay out bases without extendable VFPtrs on the second pass.
2612  if (BaseLayout.hasExtendableVFPtr()) {
2613  VBPtrOffset = Bases[BaseDecl] + BaseLayout.getNonVirtualSize();
2614  continue;
2615  }
2616  // If this is the first layout, check to see if it leads with a zero sized
2617  // object. If it does, so do we.
2618  if (CheckLeadingLayout) {
2619  CheckLeadingLayout = false;
2620  LeadsWithZeroSizedBase = BaseLayout.leadsWithZeroSizedBase();
2621  }
2622  // Lay out the base.
2623  layoutNonVirtualBase(RD, BaseDecl, BaseLayout, PreviousBaseLayout);
2624  VBPtrOffset = Bases[BaseDecl] + BaseLayout.getNonVirtualSize();
2625  }
2626  // Set our VBPtroffset if we know it at this point.
2627  if (!HasVBPtr)
2628  VBPtrOffset = CharUnits::fromQuantity(-1);
2629  else if (SharedVBPtrBase) {
2630  const ASTRecordLayout &Layout = Context.getASTRecordLayout(SharedVBPtrBase);
2631  VBPtrOffset = Bases[SharedVBPtrBase] + Layout.getVBPtrOffset();
2632  }
2633 }
2634 
2635 static bool recordUsesEBO(const RecordDecl *RD) {
2636  if (!isa<CXXRecordDecl>(RD))
2637  return false;
2638  if (RD->hasAttr<EmptyBasesAttr>())
2639  return true;
2640  if (auto *LVA = RD->getAttr<LayoutVersionAttr>())
2641  // TODO: Double check with the next version of MSVC.
2642  if (LVA->getVersion() <= LangOptions::MSVC2015)
2643  return false;
2644  // TODO: Some later version of MSVC will change the default behavior of the
2645  // compiler to enable EBO by default. When this happens, we will need an
2646  // additional isCompatibleWithMSVC check.
2647  return false;
2648 }
2649 
2650 void MicrosoftRecordLayoutBuilder::layoutNonVirtualBase(
2651  const CXXRecordDecl *RD,
2652  const CXXRecordDecl *BaseDecl,
2653  const ASTRecordLayout &BaseLayout,
2654  const ASTRecordLayout *&PreviousBaseLayout) {
2655  // Insert padding between two bases if the left first one is zero sized or
2656  // contains a zero sized subobject and the right is zero sized or one leads
2657  // with a zero sized base.
2658  bool MDCUsesEBO = recordUsesEBO(RD);
2659  if (PreviousBaseLayout && PreviousBaseLayout->endsWithZeroSizedObject() &&
2660  BaseLayout.leadsWithZeroSizedBase() && !MDCUsesEBO)
2661  Size++;
2662  ElementInfo Info = getAdjustedElementInfo(BaseLayout);
2663  CharUnits BaseOffset;
2664 
2665  // Respect the external AST source base offset, if present.
2666  bool FoundBase = false;
2667  if (UseExternalLayout) {
2668  FoundBase = External.getExternalNVBaseOffset(BaseDecl, BaseOffset);
2669  if (FoundBase) {
2670  assert(BaseOffset >= Size && "base offset already allocated");
2671  Size = BaseOffset;
2672  }
2673  }
2674 
2675  if (!FoundBase) {
2676  if (MDCUsesEBO && BaseDecl->isEmpty()) {
2677  assert(BaseLayout.getNonVirtualSize() == CharUnits::Zero());
2678  BaseOffset = CharUnits::Zero();
2679  } else {
2680  // Otherwise, lay the base out at the end of the MDC.
2681  BaseOffset = Size = Size.alignTo(Info.Alignment);
2682  }
2683  }
2684  Bases.insert(std::make_pair(BaseDecl, BaseOffset));
2685  Size += BaseLayout.getNonVirtualSize();
2686  PreviousBaseLayout = &BaseLayout;
2687 }
2688 
2689 void MicrosoftRecordLayoutBuilder::layoutFields(const RecordDecl *RD) {
2690  LastFieldIsNonZeroWidthBitfield = false;
2691  for (const FieldDecl *Field : RD->fields())
2692  layoutField(Field);
2693 }
2694 
2695 void MicrosoftRecordLayoutBuilder::layoutField(const FieldDecl *FD) {
2696  if (FD->isBitField()) {
2697  layoutBitField(FD);
2698  return;
2699  }
2700  LastFieldIsNonZeroWidthBitfield = false;
2701  ElementInfo Info = getAdjustedElementInfo(FD);
2702  Alignment = std::max(Alignment, Info.Alignment);
2703  CharUnits FieldOffset;
2704  if (UseExternalLayout)
2705  FieldOffset =
2706  Context.toCharUnitsFromBits(External.getExternalFieldOffset(FD));
2707  else if (IsUnion)
2708  FieldOffset = CharUnits::Zero();
2709  else
2710  FieldOffset = Size.alignTo(Info.Alignment);
2711  placeFieldAtOffset(FieldOffset);
2712  Size = std::max(Size, FieldOffset + Info.Size);
2713 }
2714 
2715 void MicrosoftRecordLayoutBuilder::layoutBitField(const FieldDecl *FD) {
2716  unsigned Width = FD->getBitWidthValue(Context);
2717  if (Width == 0) {
2718  layoutZeroWidthBitField(FD);
2719  return;
2720  }
2721  ElementInfo Info = getAdjustedElementInfo(FD);
2722  // Clamp the bitfield to a containable size for the sake of being able
2723  // to lay them out. Sema will throw an error.
2724  if (Width > Context.toBits(Info.Size))
2725  Width = Context.toBits(Info.Size);
2726  // Check to see if this bitfield fits into an existing allocation. Note:
2727  // MSVC refuses to pack bitfields of formal types with different sizes
2728  // into the same allocation.
2729  if (!UseExternalLayout && !IsUnion && LastFieldIsNonZeroWidthBitfield &&
2730  CurrentBitfieldSize == Info.Size && Width <= RemainingBitsInField) {
2731  placeFieldAtBitOffset(Context.toBits(Size) - RemainingBitsInField);
2732  RemainingBitsInField -= Width;
2733  return;
2734  }
2735  LastFieldIsNonZeroWidthBitfield = true;
2736  CurrentBitfieldSize = Info.Size;
2737  if (UseExternalLayout) {
2738  auto FieldBitOffset = External.getExternalFieldOffset(FD);
2739  placeFieldAtBitOffset(FieldBitOffset);
2740  auto NewSize = Context.toCharUnitsFromBits(
2741  llvm::alignDown(FieldBitOffset, Context.toBits(Info.Alignment)) +
2742  Context.toBits(Info.Size));
2743  Size = std::max(Size, NewSize);
2744  Alignment = std::max(Alignment, Info.Alignment);
2745  } else if (IsUnion) {
2746  placeFieldAtOffset(CharUnits::Zero());
2747  Size = std::max(Size, Info.Size);
2748  // TODO: Add a Sema warning that MS ignores bitfield alignment in unions.
2749  } else {
2750  // Allocate a new block of memory and place the bitfield in it.
2751  CharUnits FieldOffset = Size.alignTo(Info.Alignment);
2752  placeFieldAtOffset(FieldOffset);
2753  Size = FieldOffset + Info.Size;
2754  Alignment = std::max(Alignment, Info.Alignment);
2755  RemainingBitsInField = Context.toBits(Info.Size) - Width;
2756  }
2757 }
2758 
2759 void
2760 MicrosoftRecordLayoutBuilder::layoutZeroWidthBitField(const FieldDecl *FD) {
2761  // Zero-width bitfields are ignored unless they follow a non-zero-width
2762  // bitfield.
2763  if (!LastFieldIsNonZeroWidthBitfield) {
2764  placeFieldAtOffset(IsUnion ? CharUnits::Zero() : Size);
2765  // TODO: Add a Sema warning that MS ignores alignment for zero
2766  // sized bitfields that occur after zero-size bitfields or non-bitfields.
2767  return;
2768  }
2769  LastFieldIsNonZeroWidthBitfield = false;
2770  ElementInfo Info = getAdjustedElementInfo(FD);
2771  if (IsUnion) {
2772  placeFieldAtOffset(CharUnits::Zero());
2773  Size = std::max(Size, Info.Size);
2774  // TODO: Add a Sema warning that MS ignores bitfield alignment in unions.
2775  } else {
2776  // Round up the current record size to the field's alignment boundary.
2777  CharUnits FieldOffset = Size.alignTo(Info.Alignment);
2778  placeFieldAtOffset(FieldOffset);
2779  Size = FieldOffset;
2780  Alignment = std::max(Alignment, Info.Alignment);
2781  }
2782 }
2783 
2784 void MicrosoftRecordLayoutBuilder::injectVBPtr(const CXXRecordDecl *RD) {
2785  if (!HasVBPtr || SharedVBPtrBase)
2786  return;
2787  // Inject the VBPointer at the injection site.
2788  CharUnits InjectionSite = VBPtrOffset;
2789  // But before we do, make sure it's properly aligned.
2790  VBPtrOffset = VBPtrOffset.alignTo(PointerInfo.Alignment);
2791  // Determine where the first field should be laid out after the vbptr.
2792  CharUnits FieldStart = VBPtrOffset + PointerInfo.Size;
2793  // Shift everything after the vbptr down, unless we're using an external
2794  // layout.
2795  if (UseExternalLayout) {
2796  // It is possible that there were no fields or bases located after vbptr,
2797  // so the size was not adjusted before.
2798  if (Size < FieldStart)
2799  Size = FieldStart;
2800  return;
2801  }
2802  // Make sure that the amount we push the fields back by is a multiple of the
2803  // alignment.
2804  CharUnits Offset = (FieldStart - InjectionSite)
2805  .alignTo(std::max(RequiredAlignment, Alignment));
2806  Size += Offset;
2807  for (uint64_t &FieldOffset : FieldOffsets)
2808  FieldOffset += Context.toBits(Offset);
2809  for (BaseOffsetsMapTy::value_type &Base : Bases)
2810  if (Base.second >= InjectionSite)
2811  Base.second += Offset;
2812 }
2813 
2814 void MicrosoftRecordLayoutBuilder::injectVFPtr(const CXXRecordDecl *RD) {
2815  if (!HasOwnVFPtr)
2816  return;
2817  // Make sure that the amount we push the struct back by is a multiple of the
2818  // alignment.
2819  CharUnits Offset =
2820  PointerInfo.Size.alignTo(std::max(RequiredAlignment, Alignment));
2821  // Push back the vbptr, but increase the size of the object and push back
2822  // regular fields by the offset only if not using external record layout.
2823  if (HasVBPtr)
2824  VBPtrOffset += Offset;
2825 
2826  if (UseExternalLayout) {
2827  // The class may have no bases or fields, but still have a vfptr
2828  // (e.g. it's an interface class). The size was not correctly set before
2829  // in this case.
2830  if (FieldOffsets.empty() && Bases.empty())
2831  Size += Offset;
2832  return;
2833  }
2834 
2835  Size += Offset;
2836 
2837  // If we're using an external layout, the fields offsets have already
2838  // accounted for this adjustment.
2839  for (uint64_t &FieldOffset : FieldOffsets)
2840  FieldOffset += Context.toBits(Offset);
2841  for (BaseOffsetsMapTy::value_type &Base : Bases)
2842  Base.second += Offset;
2843 }
2844 
2845 void MicrosoftRecordLayoutBuilder::layoutVirtualBases(const CXXRecordDecl *RD) {
2846  if (!HasVBPtr)
2847  return;
2848  // Vtordisps are always 4 bytes (even in 64-bit mode)
2849  CharUnits VtorDispSize = CharUnits::fromQuantity(4);
2850  CharUnits VtorDispAlignment = VtorDispSize;
2851  // vtordisps respect pragma pack.
2852  if (!MaxFieldAlignment.isZero())
2853  VtorDispAlignment = std::min(VtorDispAlignment, MaxFieldAlignment);
2854  // The alignment of the vtordisp is at least the required alignment of the
2855  // entire record. This requirement may be present to support vtordisp
2856  // injection.
2857  for (const CXXBaseSpecifier &VBase : RD->vbases()) {
2858  const CXXRecordDecl *BaseDecl = VBase.getType()->getAsCXXRecordDecl();
2859  const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2860  RequiredAlignment =
2861  std::max(RequiredAlignment, BaseLayout.getRequiredAlignment());
2862  }
2863  VtorDispAlignment = std::max(VtorDispAlignment, RequiredAlignment);
2864  // Compute the vtordisp set.
2865  llvm::SmallPtrSet<const CXXRecordDecl *, 2> HasVtorDispSet;
2866  computeVtorDispSet(HasVtorDispSet, RD);
2867  // Iterate through the virtual bases and lay them out.
2868  const ASTRecordLayout *PreviousBaseLayout = nullptr;
2869  for (const CXXBaseSpecifier &VBase : RD->vbases()) {
2870  const CXXRecordDecl *BaseDecl = VBase.getType()->getAsCXXRecordDecl();
2871  const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2872  bool HasVtordisp = HasVtorDispSet.count(BaseDecl) > 0;
2873  // Insert padding between two bases if the left first one is zero sized or
2874  // contains a zero sized subobject and the right is zero sized or one leads
2875  // with a zero sized base. The padding between virtual bases is 4
2876  // bytes (in both 32 and 64 bits modes) and always involves rounding up to
2877  // the required alignment, we don't know why.
2878  if ((PreviousBaseLayout && PreviousBaseLayout->endsWithZeroSizedObject() &&
2879  BaseLayout.leadsWithZeroSizedBase() && !recordUsesEBO(RD)) ||
2880  HasVtordisp) {
2881  Size = Size.alignTo(VtorDispAlignment) + VtorDispSize;
2882  Alignment = std::max(VtorDispAlignment, Alignment);
2883  }
2884  // Insert the virtual base.
2885  ElementInfo Info = getAdjustedElementInfo(BaseLayout);
2886  CharUnits BaseOffset;
2887 
2888  // Respect the external AST source base offset, if present.
2889  if (UseExternalLayout) {
2890  if (!External.getExternalVBaseOffset(BaseDecl, BaseOffset))
2891  BaseOffset = Size;
2892  } else
2893  BaseOffset = Size.alignTo(Info.Alignment);
2894 
2895  assert(BaseOffset >= Size && "base offset already allocated");
2896 
2897  VBases.insert(std::make_pair(BaseDecl,
2898  ASTRecordLayout::VBaseInfo(BaseOffset, HasVtordisp)));
2899  Size = BaseOffset + BaseLayout.getNonVirtualSize();
2900  PreviousBaseLayout = &BaseLayout;
2901  }
2902 }
2903 
2904 void MicrosoftRecordLayoutBuilder::finalizeLayout(const RecordDecl *RD) {
2905  // Respect required alignment. Note that in 32-bit mode Required alignment
2906  // may be 0 and cause size not to be updated.
2907  DataSize = Size;
2908  if (!RequiredAlignment.isZero()) {
2909  Alignment = std::max(Alignment, RequiredAlignment);
2910  auto RoundingAlignment = Alignment;
2911  if (!MaxFieldAlignment.isZero())
2912  RoundingAlignment = std::min(RoundingAlignment, MaxFieldAlignment);
2913  RoundingAlignment = std::max(RoundingAlignment, RequiredAlignment);
2914  Size = Size.alignTo(RoundingAlignment);
2915  }
2916  if (Size.isZero()) {
2917  if (!recordUsesEBO(RD) || !cast<CXXRecordDecl>(RD)->isEmpty()) {
2918  EndsWithZeroSizedObject = true;
2919  LeadsWithZeroSizedBase = true;
2920  }
2921  // Zero-sized structures have size equal to their alignment if a
2922  // __declspec(align) came into play.
2923  if (RequiredAlignment >= MinEmptyStructSize)
2924  Size = Alignment;
2925  else
2926  Size = MinEmptyStructSize;
2927  }
2928 
2929  if (UseExternalLayout) {
2930  Size = Context.toCharUnitsFromBits(External.Size);
2931  if (External.Align)
2932  Alignment = Context.toCharUnitsFromBits(External.Align);
2933  }
2934 }
2935 
2936 // Recursively walks the non-virtual bases of a class and determines if any of
2937 // them are in the bases with overridden methods set.
2938 static bool
2939 RequiresVtordisp(const llvm::SmallPtrSetImpl<const CXXRecordDecl *> &
2940  BasesWithOverriddenMethods,
2941  const CXXRecordDecl *RD) {
2942  if (BasesWithOverriddenMethods.count(RD))
2943  return true;
2944  // If any of a virtual bases non-virtual bases (recursively) requires a
2945  // vtordisp than so does this virtual base.
2946  for (const CXXBaseSpecifier &Base : RD->bases())
2947  if (!Base.isVirtual() &&
2948  RequiresVtordisp(BasesWithOverriddenMethods,
2949  Base.getType()->getAsCXXRecordDecl()))
2950  return true;
2951  return false;
2952 }
2953 
2954 void MicrosoftRecordLayoutBuilder::computeVtorDispSet(
2955  llvm::SmallPtrSetImpl<const CXXRecordDecl *> &HasVtordispSet,
2956  const CXXRecordDecl *RD) const {
2957  // /vd2 or #pragma vtordisp(2): Always use vtordisps for virtual bases with
2958  // vftables.
2959  if (RD->getMSVtorDispMode() == MSVtorDispAttr::ForVFTable) {
2960  for (const CXXBaseSpecifier &Base : RD->vbases()) {
2961  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2962  const ASTRecordLayout &Layout = Context.getASTRecordLayout(BaseDecl);
2963  if (Layout.hasExtendableVFPtr())
2964  HasVtordispSet.insert(BaseDecl);
2965  }
2966  return;
2967  }
2968 
2969  // If any of our bases need a vtordisp for this type, so do we. Check our
2970  // direct bases for vtordisp requirements.
2971  for (const CXXBaseSpecifier &Base : RD->bases()) {
2972  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2973  const ASTRecordLayout &Layout = Context.getASTRecordLayout(BaseDecl);
2974  for (const auto &bi : Layout.getVBaseOffsetsMap())
2975  if (bi.second.hasVtorDisp())
2976  HasVtordispSet.insert(bi.first);
2977  }
2978  // We don't introduce any additional vtordisps if either:
2979  // * A user declared constructor or destructor aren't declared.
2980  // * #pragma vtordisp(0) or the /vd0 flag are in use.
2981  if ((!RD->hasUserDeclaredConstructor() && !RD->hasUserDeclaredDestructor()) ||
2982  RD->getMSVtorDispMode() == MSVtorDispAttr::Never)
2983  return;
2984  // /vd1 or #pragma vtordisp(1): Try to guess based on whether we think it's
2985  // possible for a partially constructed object with virtual base overrides to
2986  // escape a non-trivial constructor.
2987  assert(RD->getMSVtorDispMode() == MSVtorDispAttr::ForVBaseOverride);
2988  // Compute a set of base classes which define methods we override. A virtual
2989  // base in this set will require a vtordisp. A virtual base that transitively
2990  // contains one of these bases as a non-virtual base will also require a
2991  // vtordisp.
2992  llvm::SmallPtrSet<const CXXMethodDecl *, 8> Work;
2993  llvm::SmallPtrSet<const CXXRecordDecl *, 2> BasesWithOverriddenMethods;
2994  // Seed the working set with our non-destructor, non-pure virtual methods.
2995  for (const CXXMethodDecl *MD : RD->methods())
2996  if (MD->isVirtual() && !isa<CXXDestructorDecl>(MD) && !MD->isPure())
2997  Work.insert(MD);
2998  while (!Work.empty()) {
2999  const CXXMethodDecl *MD = *Work.begin();
3000  auto MethodRange = MD->overridden_methods();
3001  // If a virtual method has no-overrides it lives in its parent's vtable.
3002  if (MethodRange.begin() == MethodRange.end())
3003  BasesWithOverriddenMethods.insert(MD->getParent());
3004  else
3005  Work.insert(MethodRange.begin(), MethodRange.end());
3006  // We've finished processing this element, remove it from the working set.
3007  Work.erase(MD);
3008  }
3009  // For each of our virtual bases, check if it is in the set of overridden
3010  // bases or if it transitively contains a non-virtual base that is.
3011  for (const CXXBaseSpecifier &Base : RD->vbases()) {
3012  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
3013  if (!HasVtordispSet.count(BaseDecl) &&
3014  RequiresVtordisp(BasesWithOverriddenMethods, BaseDecl))
3015  HasVtordispSet.insert(BaseDecl);
3016  }
3017 }
3018 
3019 /// getASTRecordLayout - Get or compute information about the layout of the
3020 /// specified record (struct/union/class), which indicates its size and field
3021 /// position information.
3022 const ASTRecordLayout &
3024  // These asserts test different things. A record has a definition
3025  // as soon as we begin to parse the definition. That definition is
3026  // not a complete definition (which is what isDefinition() tests)
3027  // until we *finish* parsing the definition.
3028 
3029  if (D->hasExternalLexicalStorage() && !D->getDefinition())
3030  getExternalSource()->CompleteType(const_cast<RecordDecl*>(D));
3031 
3032  D = D->getDefinition();
3033  assert(D && "Cannot get layout of forward declarations!");
3034  assert(!D->isInvalidDecl() && "Cannot get layout of invalid decl!");
3035  assert(D->isCompleteDefinition() && "Cannot layout type before complete!");
3036 
3037  // Look up this layout, if already laid out, return what we have.
3038  // Note that we can't save a reference to the entry because this function
3039  // is recursive.
3040  const ASTRecordLayout *Entry = ASTRecordLayouts[D];
3041  if (Entry) return *Entry;
3042 
3043  const ASTRecordLayout *NewEntry = nullptr;
3044 
3045  if (isMsLayout(*this)) {
3046  MicrosoftRecordLayoutBuilder Builder(*this);
3047  if (const auto *RD = dyn_cast<CXXRecordDecl>(D)) {
3048  Builder.cxxLayout(RD);
3049  NewEntry = new (*this) ASTRecordLayout(
3050  *this, Builder.Size, Builder.Alignment, Builder.Alignment,
3051  Builder.RequiredAlignment,
3052  Builder.HasOwnVFPtr, Builder.HasOwnVFPtr || Builder.PrimaryBase,
3053  Builder.VBPtrOffset, Builder.DataSize, Builder.FieldOffsets,
3054  Builder.NonVirtualSize, Builder.Alignment, CharUnits::Zero(),
3055  Builder.PrimaryBase, false, Builder.SharedVBPtrBase,
3056  Builder.EndsWithZeroSizedObject, Builder.LeadsWithZeroSizedBase,
3057  Builder.Bases, Builder.VBases);
3058  } else {
3059  Builder.layout(D);
3060  NewEntry = new (*this) ASTRecordLayout(
3061  *this, Builder.Size, Builder.Alignment, Builder.Alignment,
3062  Builder.RequiredAlignment,
3063  Builder.Size, Builder.FieldOffsets);
3064  }
3065  } else {
3066  if (const auto *RD = dyn_cast<CXXRecordDecl>(D)) {
3067  EmptySubobjectMap EmptySubobjects(*this, RD);
3068  ItaniumRecordLayoutBuilder Builder(*this, &EmptySubobjects);
3069  Builder.Layout(RD);
3070 
3071  // In certain situations, we are allowed to lay out objects in the
3072  // tail-padding of base classes. This is ABI-dependent.
3073  // FIXME: this should be stored in the record layout.
3074  bool skipTailPadding =
3075  mustSkipTailPadding(getTargetInfo().getCXXABI(), RD);
3076 
3077  // FIXME: This should be done in FinalizeLayout.
3078  CharUnits DataSize =
3079  skipTailPadding ? Builder.getSize() : Builder.getDataSize();
3080  CharUnits NonVirtualSize =
3081  skipTailPadding ? DataSize : Builder.NonVirtualSize;
3082  NewEntry = new (*this) ASTRecordLayout(
3083  *this, Builder.getSize(), Builder.Alignment, Builder.UnadjustedAlignment,
3084  /*RequiredAlignment : used by MS-ABI)*/
3085  Builder.Alignment, Builder.HasOwnVFPtr, RD->isDynamicClass(),
3086  CharUnits::fromQuantity(-1), DataSize, Builder.FieldOffsets,
3087  NonVirtualSize, Builder.NonVirtualAlignment,
3088  EmptySubobjects.SizeOfLargestEmptySubobject, Builder.PrimaryBase,
3089  Builder.PrimaryBaseIsVirtual, nullptr, false, false, Builder.Bases,
3090  Builder.VBases);
3091  } else {
3092  ItaniumRecordLayoutBuilder Builder(*this, /*EmptySubobjects=*/nullptr);
3093  Builder.Layout(D);
3094 
3095  NewEntry = new (*this) ASTRecordLayout(
3096  *this, Builder.getSize(), Builder.Alignment, Builder.UnadjustedAlignment,
3097  /*RequiredAlignment : used by MS-ABI)*/
3098  Builder.Alignment, Builder.getSize(), Builder.FieldOffsets);
3099  }
3100  }
3101 
3102  ASTRecordLayouts[D] = NewEntry;
3103 
3104  if (getLangOpts().DumpRecordLayouts) {
3105  llvm::outs() << "\n*** Dumping AST Record Layout\n";
3106  DumpRecordLayout(D, llvm::outs(), getLangOpts().DumpRecordLayoutsSimple);
3107  }
3108 
3109  return *NewEntry;
3110 }
3111 
3113  if (!getTargetInfo().getCXXABI().hasKeyFunctions())
3114  return nullptr;
3115 
3116  assert(RD->getDefinition() && "Cannot get key function for forward decl!");
3117  RD = RD->getDefinition();
3118 
3119  // Beware:
3120  // 1) computing the key function might trigger deserialization, which might
3121  // invalidate iterators into KeyFunctions
3122  // 2) 'get' on the LazyDeclPtr might also trigger deserialization and
3123  // invalidate the LazyDeclPtr within the map itself
3124  LazyDeclPtr Entry = KeyFunctions[RD];
3125  const Decl *Result =
3126  Entry ? Entry.get(getExternalSource()) : computeKeyFunction(*this, RD);
3127 
3128  // Store it back if it changed.
3129  if (Entry.isOffset() || Entry.isValid() != bool(Result))
3130  KeyFunctions[RD] = const_cast<Decl*>(Result);
3131 
3132  return cast_or_null<CXXMethodDecl>(Result);
3133 }
3134 
3136  assert(Method == Method->getFirstDecl() &&
3137  "not working with method declaration from class definition");
3138 
3139  // Look up the cache entry. Since we're working with the first
3140  // declaration, its parent must be the class definition, which is
3141  // the correct key for the KeyFunctions hash.
3142  const auto &Map = KeyFunctions;
3143  auto I = Map.find(Method->getParent());
3144 
3145  // If it's not cached, there's nothing to do.
3146  if (I == Map.end()) return;
3147 
3148  // If it is cached, check whether it's the target method, and if so,
3149  // remove it from the cache. Note, the call to 'get' might invalidate
3150  // the iterator and the LazyDeclPtr object within the map.
3151  LazyDeclPtr Ptr = I->second;
3152  if (Ptr.get(getExternalSource()) == Method) {
3153  // FIXME: remember that we did this for module / chained PCH state?
3154  KeyFunctions.erase(Method->getParent());
3155  }
3156 }
3157 
3158 static uint64_t getFieldOffset(const ASTContext &C, const FieldDecl *FD) {
3159  const ASTRecordLayout &Layout = C.getASTRecordLayout(FD->getParent());
3160  return Layout.getFieldOffset(FD->getFieldIndex());
3161 }
3162 
3163 uint64_t ASTContext::getFieldOffset(const ValueDecl *VD) const {
3164  uint64_t OffsetInBits;
3165  if (const FieldDecl *FD = dyn_cast<FieldDecl>(VD)) {
3166  OffsetInBits = ::getFieldOffset(*this, FD);
3167  } else {
3168  const IndirectFieldDecl *IFD = cast<IndirectFieldDecl>(VD);
3169 
3170  OffsetInBits = 0;
3171  for (const NamedDecl *ND : IFD->chain())
3172  OffsetInBits += ::getFieldOffset(*this, cast<FieldDecl>(ND));
3173  }
3174 
3175  return OffsetInBits;
3176 }
3177 
3179  const ObjCImplementationDecl *ID,
3180  const ObjCIvarDecl *Ivar) const {
3181  const ObjCInterfaceDecl *Container = Ivar->getContainingInterface();
3182 
3183  // FIXME: We should eliminate the need to have ObjCImplementationDecl passed
3184  // in here; it should never be necessary because that should be the lexical
3185  // decl context for the ivar.
3186 
3187  // If we know have an implementation (and the ivar is in it) then
3188  // look up in the implementation layout.
3189  const ASTRecordLayout *RL;
3190  if (ID && declaresSameEntity(ID->getClassInterface(), Container))
3191  RL = &getASTObjCImplementationLayout(ID);
3192  else
3193  RL = &getASTObjCInterfaceLayout(Container);
3194 
3195  // Compute field index.
3196  //
3197  // FIXME: The index here is closely tied to how ASTContext::getObjCLayout is
3198  // implemented. This should be fixed to get the information from the layout
3199  // directly.
3200  unsigned Index = 0;
3201 
3202  for (const ObjCIvarDecl *IVD = Container->all_declared_ivar_begin();
3203  IVD; IVD = IVD->getNextIvar()) {
3204  if (Ivar == IVD)
3205  break;
3206  ++Index;
3207  }
3208  assert(Index < RL->getFieldCount() && "Ivar is not inside record layout!");
3209 
3210  return RL->getFieldOffset(Index);
3211 }
3212 
3213 /// getObjCLayout - Get or compute information about the layout of the
3214 /// given interface.
3215 ///
3216 /// \param Impl - If given, also include the layout of the interface's
3217 /// implementation. This may differ by including synthesized ivars.
3218 const ASTRecordLayout &
3219 ASTContext::getObjCLayout(const ObjCInterfaceDecl *D,
3220  const ObjCImplementationDecl *Impl) const {
3221  // Retrieve the definition
3222  if (D->hasExternalLexicalStorage() && !D->getDefinition())
3223  getExternalSource()->CompleteType(const_cast<ObjCInterfaceDecl*>(D));
3224  D = D->getDefinition();
3225  assert(D && D->isThisDeclarationADefinition() && "Invalid interface decl!");
3226 
3227  // Look up this layout, if already laid out, return what we have.
3228  const ObjCContainerDecl *Key =
3229  Impl ? (const ObjCContainerDecl*) Impl : (const ObjCContainerDecl*) D;
3230  if (const ASTRecordLayout *Entry = ObjCLayouts[Key])
3231  return *Entry;
3232 
3233  // Add in synthesized ivar count if laying out an implementation.
3234  if (Impl) {
3235  unsigned SynthCount = CountNonClassIvars(D);
3236  // If there aren't any synthesized ivars then reuse the interface
3237  // entry. Note we can't cache this because we simply free all
3238  // entries later; however we shouldn't look up implementations
3239  // frequently.
3240  if (SynthCount == 0)
3241  return getObjCLayout(D, nullptr);
3242  }
3243 
3244  ItaniumRecordLayoutBuilder Builder(*this, /*EmptySubobjects=*/nullptr);
3245  Builder.Layout(D);
3246 
3247  const ASTRecordLayout *NewEntry =
3248  new (*this) ASTRecordLayout(*this, Builder.getSize(),
3249  Builder.Alignment,
3250  Builder.UnadjustedAlignment,
3251  /*RequiredAlignment : used by MS-ABI)*/
3252  Builder.Alignment,
3253  Builder.getDataSize(),
3254  Builder.FieldOffsets);
3255 
3256  ObjCLayouts[Key] = NewEntry;
3257 
3258  return *NewEntry;
3259 }
3260 
3261 static void PrintOffset(raw_ostream &OS,
3262  CharUnits Offset, unsigned IndentLevel) {
3263  OS << llvm::format("%10" PRId64 " | ", (int64_t)Offset.getQuantity());
3264  OS.indent(IndentLevel * 2);
3265 }
3266 
3267 static void PrintBitFieldOffset(raw_ostream &OS, CharUnits Offset,
3268  unsigned Begin, unsigned Width,
3269  unsigned IndentLevel) {
3270  llvm::SmallString<10> Buffer;
3271  {
3272  llvm::raw_svector_ostream BufferOS(Buffer);
3273  BufferOS << Offset.getQuantity() << ':';
3274  if (Width == 0) {
3275  BufferOS << '-';
3276  } else {
3277  BufferOS << Begin << '-' << (Begin + Width - 1);
3278  }
3279  }
3280 
3281  OS << llvm::right_justify(Buffer, 10) << " | ";
3282  OS.indent(IndentLevel * 2);
3283 }
3284 
3285 static void PrintIndentNoOffset(raw_ostream &OS, unsigned IndentLevel) {
3286  OS << " | ";
3287  OS.indent(IndentLevel * 2);
3288 }
3289 
3290 static void DumpRecordLayout(raw_ostream &OS, const RecordDecl *RD,
3291  const ASTContext &C,
3292  CharUnits Offset,
3293  unsigned IndentLevel,
3294  const char* Description,
3295  bool PrintSizeInfo,
3296  bool IncludeVirtualBases) {
3297  const ASTRecordLayout &Layout = C.getASTRecordLayout(RD);
3298  auto CXXRD = dyn_cast<CXXRecordDecl>(RD);
3299 
3300  PrintOffset(OS, Offset, IndentLevel);
3301  OS << C.getTypeDeclType(const_cast<RecordDecl*>(RD)).getAsString();
3302  if (Description)
3303  OS << ' ' << Description;
3304  if (CXXRD && CXXRD->isEmpty())
3305  OS << " (empty)";
3306  OS << '\n';
3307 
3308  IndentLevel++;
3309 
3310  // Dump bases.
3311  if (CXXRD) {
3312  const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
3313  bool HasOwnVFPtr = Layout.hasOwnVFPtr();
3314  bool HasOwnVBPtr = Layout.hasOwnVBPtr();
3315 
3316  // Vtable pointer.
3317  if (CXXRD->isDynamicClass() && !PrimaryBase && !isMsLayout(C)) {
3318  PrintOffset(OS, Offset, IndentLevel);
3319  OS << '(' << *RD << " vtable pointer)\n";
3320  } else if (HasOwnVFPtr) {
3321  PrintOffset(OS, Offset, IndentLevel);
3322  // vfptr (for Microsoft C++ ABI)
3323  OS << '(' << *RD << " vftable pointer)\n";
3324  }
3325 
3326  // Collect nvbases.
3328  for (const CXXBaseSpecifier &Base : CXXRD->bases()) {
3329  assert(!Base.getType()->isDependentType() &&
3330  "Cannot layout class with dependent bases.");
3331  if (!Base.isVirtual())
3332  Bases.push_back(Base.getType()->getAsCXXRecordDecl());
3333  }
3334 
3335  // Sort nvbases by offset.
3336  llvm::stable_sort(
3337  Bases, [&](const CXXRecordDecl *L, const CXXRecordDecl *R) {
3338  return Layout.getBaseClassOffset(L) < Layout.getBaseClassOffset(R);
3339  });
3340 
3341  // Dump (non-virtual) bases
3342  for (const CXXRecordDecl *Base : Bases) {
3343  CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base);
3344  DumpRecordLayout(OS, Base, C, BaseOffset, IndentLevel,
3345  Base == PrimaryBase ? "(primary base)" : "(base)",
3346  /*PrintSizeInfo=*/false,
3347  /*IncludeVirtualBases=*/false);
3348  }
3349 
3350  // vbptr (for Microsoft C++ ABI)
3351  if (HasOwnVBPtr) {
3352  PrintOffset(OS, Offset + Layout.getVBPtrOffset(), IndentLevel);
3353  OS << '(' << *RD << " vbtable pointer)\n";
3354  }
3355  }
3356 
3357  // Dump fields.
3358  uint64_t FieldNo = 0;
3359  for (RecordDecl::field_iterator I = RD->field_begin(),
3360  E = RD->field_end(); I != E; ++I, ++FieldNo) {
3361  const FieldDecl &Field = **I;
3362  uint64_t LocalFieldOffsetInBits = Layout.getFieldOffset(FieldNo);
3363  CharUnits FieldOffset =
3364  Offset + C.toCharUnitsFromBits(LocalFieldOffsetInBits);
3365 
3366  // Recursively dump fields of record type.
3367  if (auto RT = Field.getType()->getAs<RecordType>()) {
3368  DumpRecordLayout(OS, RT->getDecl(), C, FieldOffset, IndentLevel,
3369  Field.getName().data(),
3370  /*PrintSizeInfo=*/false,
3371  /*IncludeVirtualBases=*/true);
3372  continue;
3373  }
3374 
3375  if (Field.isBitField()) {
3376  uint64_t LocalFieldByteOffsetInBits = C.toBits(FieldOffset - Offset);
3377  unsigned Begin = LocalFieldOffsetInBits - LocalFieldByteOffsetInBits;
3378  unsigned Width = Field.getBitWidthValue(C);
3379  PrintBitFieldOffset(OS, FieldOffset, Begin, Width, IndentLevel);
3380  } else {
3381  PrintOffset(OS, FieldOffset, IndentLevel);
3382  }
3383  OS << Field.getType().getAsString() << ' ' << Field << '\n';
3384  }
3385 
3386  // Dump virtual bases.
3387  if (CXXRD && IncludeVirtualBases) {
3388  const ASTRecordLayout::VBaseOffsetsMapTy &VtorDisps =
3389  Layout.getVBaseOffsetsMap();
3390 
3391  for (const CXXBaseSpecifier &Base : CXXRD->vbases()) {
3392  assert(Base.isVirtual() && "Found non-virtual class!");
3393  const CXXRecordDecl *VBase = Base.getType()->getAsCXXRecordDecl();
3394 
3395  CharUnits VBaseOffset = Offset + Layout.getVBaseClassOffset(VBase);
3396 
3397  if (VtorDisps.find(VBase)->second.hasVtorDisp()) {
3398  PrintOffset(OS, VBaseOffset - CharUnits::fromQuantity(4), IndentLevel);
3399  OS << "(vtordisp for vbase " << *VBase << ")\n";
3400  }
3401 
3402  DumpRecordLayout(OS, VBase, C, VBaseOffset, IndentLevel,
3403  VBase == Layout.getPrimaryBase() ?
3404  "(primary virtual base)" : "(virtual base)",
3405  /*PrintSizeInfo=*/false,
3406  /*IncludeVirtualBases=*/false);
3407  }
3408  }
3409 
3410  if (!PrintSizeInfo) return;
3411 
3412  PrintIndentNoOffset(OS, IndentLevel - 1);
3413  OS << "[sizeof=" << Layout.getSize().getQuantity();
3414  if (CXXRD && !isMsLayout(C))
3415  OS << ", dsize=" << Layout.getDataSize().getQuantity();
3416  OS << ", align=" << Layout.getAlignment().getQuantity();
3417 
3418  if (CXXRD) {
3419  OS << ",\n";
3420  PrintIndentNoOffset(OS, IndentLevel - 1);
3421  OS << " nvsize=" << Layout.getNonVirtualSize().getQuantity();
3422  OS << ", nvalign=" << Layout.getNonVirtualAlignment().getQuantity();
3423  }
3424  OS << "]\n";
3425 }
3426 
3428  raw_ostream &OS,
3429  bool Simple) const {
3430  if (!Simple) {
3431  ::DumpRecordLayout(OS, RD, *this, CharUnits(), 0, nullptr,
3432  /*PrintSizeInfo*/true,
3433  /*IncludeVirtualBases=*/true);
3434  return;
3435  }
3436 
3437  // The "simple" format is designed to be parsed by the
3438  // layout-override testing code. There shouldn't be any external
3439  // uses of this format --- when LLDB overrides a layout, it sets up
3440  // the data structures directly --- so feel free to adjust this as
3441  // you like as long as you also update the rudimentary parser for it
3442  // in libFrontend.
3443 
3444  const ASTRecordLayout &Info = getASTRecordLayout(RD);
3445  OS << "Type: " << getTypeDeclType(RD).getAsString() << "\n";
3446  OS << "\nLayout: ";
3447  OS << "<ASTRecordLayout\n";
3448  OS << " Size:" << toBits(Info.getSize()) << "\n";
3449  if (!isMsLayout(*this))
3450  OS << " DataSize:" << toBits(Info.getDataSize()) << "\n";
3451  OS << " Alignment:" << toBits(Info.getAlignment()) << "\n";
3452  OS << " FieldOffsets: [";
3453  for (unsigned i = 0, e = Info.getFieldCount(); i != e; ++i) {
3454  if (i) OS << ", ";
3455  OS << Info.getFieldOffset(i);
3456  }
3457  OS << "]>\n";
3458 }
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:1748
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:643
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:825
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:991
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:840
Decl - This represents one declaration (or definition), e.g.
Definition: DeclBase.h:88
bool isPOD() const
Whether this class is a POD-type (C++ [class]p4)
Definition: DeclCXX.h:1317
unsigned getFieldIndex() const
Returns the index of this field within its record, as appropriate for passing to ASTRecordLayout::get...
Definition: Decl.cpp:3949
const RecordDecl * getParent() const
Returns the parent of this field declaration, which is the struct in which this field is defined...
Definition: Decl.h:2796
The base class of the type hierarchy.
Definition: Type.h:1418
DiagnosticsEngine & getDiagnostics() const
DiagnosticBuilder Report(SourceLocation Loc, unsigned DiagID)
Issue the message to the client.
Definition: Diagnostic.h:1297
Represents an array type, per C99 6.7.5.2 - Array Declarators.
Definition: Type.h:2832
bool isZero() const
isZero - Test whether the quantity equals zero.
Definition: CharUnits.h:115
const TargetInfo & getTargetInfo() const
Definition: ASTContext.h:693
CharUnits getAlignment() const
getAlignment - Get the record alignment in characters.
Definition: RecordLayout.h:176
unsigned getCharWidth() const
Definition: TargetInfo.h:382
QualType getElementType() const
Definition: Type.h:2867
bool isCompleteDefinition() const
Return true if this decl has its body fully specified.
Definition: Decl.h:3202
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:6821
unsigned getCharAlign() const
Definition: TargetInfo.h:383
The "__interface" keyword.
Definition: Type.h:5094
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:553
unsigned getZeroLengthBitfieldBoundary() const
Get the fixed alignment value in bits for a member that follows a zero length bitfield.
Definition: TargetInfo.h:706
bool mayInsertExtraPadding(bool EmitRemark=false) const
Whether we are allowed to insert extra padding between fields.
Definition: Decl.cpp:4344
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:3626
uint64_t getPointerWidth(unsigned AddrSpace) const
Return the width of pointers on this target, for the specified address space.
Definition: TargetInfo.h:360
bool isEmpty() const
Determine whether this is an empty class in the sense of (C++11 [meta.unary.prop]).
Definition: DeclCXX.h:1332
TargetCXXABI getCXXABI() const
Get the C++ ABI currently in use.
Definition: TargetInfo.h:1060
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:3807
field_range fields() const
Definition: Decl.h:3817
Represents a member of a struct/union/class.
Definition: Decl.h:2607
bool hasUserDeclaredDestructor() const
Determine whether this class has a user-declared destructor.
Definition: DeclCXX.h:1181
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:873
__DEVICE__ int max(int __a, int __b)
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:3814
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:2685
ObjCContainerDecl - Represents a container for method declarations.
Definition: DeclObjC.h:968
TagKind getTagKind() const
Definition: Decl.h:3276
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:2880
unsigned Align
Definition: ASTContext.h:144
field_iterator field_begin() const
Definition: Decl.cpp:4297
unsigned getBitWidthValue(const ASTContext &Ctx) const
Definition: Decl.cpp:3906
bool declaresSameEntity(const Decl *D1, const Decl *D2)
Determine whether two declarations declare the same entity.
Definition: DeclBase.h:1166
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:700
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:1012
lookup_result lookup(DeclarationName Name) const
lookup - Find the declarations (if any) with the given Name in this context.
Definition: DeclBase.cpp:1602
bool hasAttr() const
Definition: DeclBase.h:542
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:1045
CXXRecordDecl * getAsCXXRecordDecl() const
Retrieves the CXXRecordDecl that this type refers to, either because the type is a RecordType or beca...
Definition: Type.cpp:1636
bool isDynamicClass() const
Definition: DeclCXX.h:791
bool useExplicitBitFieldAlignment() const
Check whether explicit bitfield alignment attributes should be.
Definition: TargetInfo.h:712
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:1665
QuantityType getQuantity() const
getQuantity - Get the raw integer representation of this quantity.
Definition: CharUnits.h:178
unsigned Offset
Definition: Format.cpp:1728
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:4314
bool isInlineSpecified() const
Determine whether the "inline" keyword was specified for this function.
Definition: Decl.h:2377
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:3820
#define bool
Definition: stdbool.h:15
CharUnits getSizeOfLargestEmptySubobject() const
Definition: RecordLayout.h:247
overridden_method_range overridden_methods() const
Definition: DeclCXX.cpp:2250
CharUnits getTypeAlignInChars(QualType T) const
Return the ABI-specified alignment of a (complete) type T, in characters.
CXXRecordDecl * getDefinition() const
Definition: DeclCXX.h:771
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:1558
bool isPolymorphic() const
Whether this class is polymorphic (C++ [class.virtual]), which means that the class contains or inher...
Definition: DeclCXX.h:1350
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:384
method_iterator method_end() const
Method past-the-end iterator.
Definition: DeclCXX.h:878
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:6761
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:1389
The result type of a method or function.
This template specialization was implicitly instantiated from a template.
Definition: Specifiers.h:180
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:708
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:4436
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:17
The "struct" keyword.
Definition: Type.h:5091
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:2114
const ConstantArrayType * getAsConstantArrayType(QualType T) const
Definition: ASTContext.h:2432
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:2336
This template specialization was instantiated from a template due to an explicit instantiation defini...
Definition: Specifiers.h:192
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:694
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:3680
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:1012
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:5089
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:2858
CanQualType UnsignedLongLongTy
Definition: ASTContext.h:1013
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:188
bool hasUserDeclaredConstructor() const
Determine whether this class has any user-declared constructors.
Definition: DeclCXX.h:985
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:1365
static std::string getAsString(SplitQualType split, const PrintingPolicy &Policy)
Definition: Type.h:976
const CXXRecordDecl * getParent() const
Return the parent of this method declaration, which is the class in which this method is defined...
Definition: DeclCXX.h:2237
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:174
ExternalASTSource * getExternalSource() const
Retrieve a pointer to the external AST source associated with this AST context, if any...
Definition: ASTContext.h:1072
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:2041
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:6418
A helper class that allows the use of isa/cast/dyncast to detect TagType objects of structs/unions/cl...
Definition: Type.h:4426
CanQualType UnsignedLongTy
Definition: ASTContext.h:1012
static bool RequiresVtordisp(const llvm::SmallPtrSetImpl< const CXXRecordDecl *> &BasesWithOverriddenMethods, const CXXRecordDecl *RD)
T * getAttr() const
Definition: DeclBase.h:538
uint64_t getCharWidth() const
Return the size of the character type, in bits.
Definition: ASTContext.h:2074
void setNonKeyFunction(const CXXMethodDecl *method)
Observe that the given method cannot be a key function.
Base for LValueReferenceType and RValueReferenceType.
Definition: Type.h:2693
The "class" keyword.
Definition: Type.h:5100
Represents a base class of a C++ class.
Definition: DeclCXX.h:192
uint64_t getTypeSize(QualType T) const
Return the size of the specified (complete) type T, in bits.
Definition: ASTContext.h:2070
uint64_t getFieldOffset(const ValueDecl *FD) const
Get the offset of a FieldDecl or IndirectFieldDecl, in bits.
CharUnits toCharUnitsFromBits(int64_t BitSize) const
Convert a size in bits to a size in characters.
Defines the C++ Decl subclasses, other than those for templates (found in DeclTemplate.h) and friends (in DeclFriend.h).
int64_t toBits(CharUnits CharSize) const
Convert a size in characters to a size in bits.
const CXXMethodDecl * getCurrentKeyFunction(const CXXRecordDecl *RD)
Get our current best idea for the key function of the given record decl, or nullptr if there isn&#39;t on...
Represents a C++ struct/union/class.
Definition: DeclCXX.h:300
TypeInfo getTypeInfo(const Type *T) const
Get the size and alignment of the specified complete type in bits.
ObjCIvarDecl - Represents an ObjC instance variable.
Definition: DeclObjC.h: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:2408
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
__DEVICE__ int min(int __a, int __b)
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:363
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
bool isUnion() const
Definition: Decl.h:3285
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:2523
const LangOptions & getLangOpts() const
Definition: ASTContext.h:710
Represents the canonical version of C arrays with a specified constant size.
Definition: Type.h:2892
base_class_range vbases()
Definition: DeclCXX.h:842
SourceLocation getLocation() const
Definition: DeclBase.h:429
bool isExternallyVisible() const
Definition: Decl.h:379
CanQualType UnsignedIntTy
Definition: ASTContext.h:1012
bool leadsWithZeroSizedBase() const
Definition: RecordLayout.h:298
method_range methods() const
Definition: DeclCXX.h:867