1 //=== RecordLayoutBuilder.cpp - Helper class for building record layouts ---==//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 #include "clang/AST/RecordLayout.h"
11 #include "clang/AST/ASTContext.h"
12 #include "clang/AST/Attr.h"
13 #include "clang/AST/CXXInheritance.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 "clang/Sema/SemaDiagnostic.h"
20 #include "llvm/ADT/SmallSet.h"
21 #include "llvm/Support/CrashRecoveryContext.h"
22 #include "llvm/Support/Format.h"
23 #include "llvm/Support/MathExtras.h"
25 using namespace clang;
29 /// BaseSubobjectInfo - Represents a single base subobject in a complete class.
30 /// For a class hierarchy like
34 /// class C : A, B { };
36 /// The BaseSubobjectInfo graph for C will have three BaseSubobjectInfo
37 /// instances, one for B and two for A.
39 /// If a base is virtual, it will only have one BaseSubobjectInfo allocated.
40 struct BaseSubobjectInfo {
41 /// Class - The class for this base info.
42 const CXXRecordDecl *Class;
44 /// IsVirtual - Whether the BaseInfo represents a virtual base or not.
47 /// Bases - Information about the base subobjects.
48 SmallVector<BaseSubobjectInfo*, 4> Bases;
50 /// PrimaryVirtualBaseInfo - Holds the base info for the primary virtual base
51 /// of this base info (if one exists).
52 BaseSubobjectInfo *PrimaryVirtualBaseInfo;
55 const BaseSubobjectInfo *Derived;
58 /// EmptySubobjectMap - Keeps track of which empty subobjects exist at different
59 /// offsets while laying out a C++ class.
60 class EmptySubobjectMap {
61 const ASTContext &Context;
64 /// Class - The class whose empty entries we're keeping track of.
65 const CXXRecordDecl *Class;
67 /// EmptyClassOffsets - A map from offsets to empty record decls.
68 typedef llvm::TinyPtrVector<const CXXRecordDecl *> ClassVectorTy;
69 typedef llvm::DenseMap<CharUnits, ClassVectorTy> EmptyClassOffsetsMapTy;
70 EmptyClassOffsetsMapTy EmptyClassOffsets;
72 /// MaxEmptyClassOffset - The highest offset known to contain an empty
74 CharUnits MaxEmptyClassOffset;
76 /// ComputeEmptySubobjectSizes - Compute the size of the largest base or
77 /// member subobject that is empty.
78 void ComputeEmptySubobjectSizes();
80 void AddSubobjectAtOffset(const CXXRecordDecl *RD, CharUnits Offset);
82 void UpdateEmptyBaseSubobjects(const BaseSubobjectInfo *Info,
83 CharUnits Offset, bool PlacingEmptyBase);
85 void UpdateEmptyFieldSubobjects(const CXXRecordDecl *RD,
86 const CXXRecordDecl *Class,
88 void UpdateEmptyFieldSubobjects(const FieldDecl *FD, CharUnits Offset);
90 /// AnyEmptySubobjectsBeyondOffset - Returns whether there are any empty
91 /// subobjects beyond the given offset.
92 bool AnyEmptySubobjectsBeyondOffset(CharUnits Offset) const {
93 return Offset <= MaxEmptyClassOffset;
97 getFieldOffset(const ASTRecordLayout &Layout, unsigned FieldNo) const {
98 uint64_t FieldOffset = Layout.getFieldOffset(FieldNo);
99 assert(FieldOffset % CharWidth == 0 &&
100 "Field offset not at char boundary!");
102 return Context.toCharUnitsFromBits(FieldOffset);
106 bool CanPlaceSubobjectAtOffset(const CXXRecordDecl *RD,
107 CharUnits Offset) const;
109 bool CanPlaceBaseSubobjectAtOffset(const BaseSubobjectInfo *Info,
112 bool CanPlaceFieldSubobjectAtOffset(const CXXRecordDecl *RD,
113 const CXXRecordDecl *Class,
114 CharUnits Offset) const;
115 bool CanPlaceFieldSubobjectAtOffset(const FieldDecl *FD,
116 CharUnits Offset) const;
119 /// This holds the size of the largest empty subobject (either a base
120 /// or a member). Will be zero if the record being built doesn't contain
121 /// any empty classes.
122 CharUnits SizeOfLargestEmptySubobject;
124 EmptySubobjectMap(const ASTContext &Context, const CXXRecordDecl *Class)
125 : Context(Context), CharWidth(Context.getCharWidth()), Class(Class) {
126 ComputeEmptySubobjectSizes();
129 /// CanPlaceBaseAtOffset - Return whether the given base class can be placed
130 /// at the given offset.
131 /// Returns false if placing the record will result in two components
132 /// (direct or indirect) of the same type having the same offset.
133 bool CanPlaceBaseAtOffset(const BaseSubobjectInfo *Info,
136 /// CanPlaceFieldAtOffset - Return whether a field can be placed at the given
138 bool CanPlaceFieldAtOffset(const FieldDecl *FD, CharUnits Offset);
141 void EmptySubobjectMap::ComputeEmptySubobjectSizes() {
143 for (const CXXBaseSpecifier &Base : Class->bases()) {
144 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
147 const ASTRecordLayout &Layout = Context.getASTRecordLayout(BaseDecl);
148 if (BaseDecl->isEmpty()) {
149 // If the class decl is empty, get its size.
150 EmptySize = Layout.getSize();
152 // Otherwise, we get the largest empty subobject for the decl.
153 EmptySize = Layout.getSizeOfLargestEmptySubobject();
156 if (EmptySize > SizeOfLargestEmptySubobject)
157 SizeOfLargestEmptySubobject = EmptySize;
161 for (const FieldDecl *FD : Class->fields()) {
162 const RecordType *RT =
163 Context.getBaseElementType(FD->getType())->getAs<RecordType>();
165 // We only care about record types.
170 const CXXRecordDecl *MemberDecl = RT->getAsCXXRecordDecl();
171 const ASTRecordLayout &Layout = Context.getASTRecordLayout(MemberDecl);
172 if (MemberDecl->isEmpty()) {
173 // If the class decl is empty, get its size.
174 EmptySize = Layout.getSize();
176 // Otherwise, we get the largest empty subobject for the decl.
177 EmptySize = Layout.getSizeOfLargestEmptySubobject();
180 if (EmptySize > SizeOfLargestEmptySubobject)
181 SizeOfLargestEmptySubobject = EmptySize;
186 EmptySubobjectMap::CanPlaceSubobjectAtOffset(const CXXRecordDecl *RD,
187 CharUnits Offset) const {
188 // We only need to check empty bases.
192 EmptyClassOffsetsMapTy::const_iterator I = EmptyClassOffsets.find(Offset);
193 if (I == EmptyClassOffsets.end())
196 const ClassVectorTy &Classes = I->second;
197 if (std::find(Classes.begin(), Classes.end(), RD) == Classes.end())
200 // There is already an empty class of the same type at this offset.
204 void EmptySubobjectMap::AddSubobjectAtOffset(const CXXRecordDecl *RD,
206 // We only care about empty bases.
210 // If we have empty structures inside a union, we can assign both
211 // the same offset. Just avoid pushing them twice in the list.
212 ClassVectorTy &Classes = EmptyClassOffsets[Offset];
213 if (std::find(Classes.begin(), Classes.end(), RD) != Classes.end())
216 Classes.push_back(RD);
218 // Update the empty class offset.
219 if (Offset > MaxEmptyClassOffset)
220 MaxEmptyClassOffset = Offset;
224 EmptySubobjectMap::CanPlaceBaseSubobjectAtOffset(const BaseSubobjectInfo *Info,
226 // We don't have to keep looking past the maximum offset that's known to
227 // contain an empty class.
228 if (!AnyEmptySubobjectsBeyondOffset(Offset))
231 if (!CanPlaceSubobjectAtOffset(Info->Class, Offset))
234 // Traverse all non-virtual bases.
235 const ASTRecordLayout &Layout = Context.getASTRecordLayout(Info->Class);
236 for (const BaseSubobjectInfo *Base : Info->Bases) {
240 CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base->Class);
242 if (!CanPlaceBaseSubobjectAtOffset(Base, BaseOffset))
246 if (Info->PrimaryVirtualBaseInfo) {
247 BaseSubobjectInfo *PrimaryVirtualBaseInfo = Info->PrimaryVirtualBaseInfo;
249 if (Info == PrimaryVirtualBaseInfo->Derived) {
250 if (!CanPlaceBaseSubobjectAtOffset(PrimaryVirtualBaseInfo, Offset))
255 // Traverse all member variables.
256 unsigned FieldNo = 0;
257 for (CXXRecordDecl::field_iterator I = Info->Class->field_begin(),
258 E = Info->Class->field_end(); I != E; ++I, ++FieldNo) {
262 CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
263 if (!CanPlaceFieldSubobjectAtOffset(*I, FieldOffset))
270 void EmptySubobjectMap::UpdateEmptyBaseSubobjects(const BaseSubobjectInfo *Info,
272 bool PlacingEmptyBase) {
273 if (!PlacingEmptyBase && Offset >= SizeOfLargestEmptySubobject) {
274 // We know that the only empty subobjects that can conflict with empty
275 // subobject of non-empty bases, are empty bases that can be placed at
276 // offset zero. Because of this, we only need to keep track of empty base
277 // subobjects with offsets less than the size of the largest empty
278 // subobject for our class.
282 AddSubobjectAtOffset(Info->Class, Offset);
284 // Traverse all non-virtual bases.
285 const ASTRecordLayout &Layout = Context.getASTRecordLayout(Info->Class);
286 for (const BaseSubobjectInfo *Base : Info->Bases) {
290 CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base->Class);
291 UpdateEmptyBaseSubobjects(Base, BaseOffset, PlacingEmptyBase);
294 if (Info->PrimaryVirtualBaseInfo) {
295 BaseSubobjectInfo *PrimaryVirtualBaseInfo = Info->PrimaryVirtualBaseInfo;
297 if (Info == PrimaryVirtualBaseInfo->Derived)
298 UpdateEmptyBaseSubobjects(PrimaryVirtualBaseInfo, Offset,
302 // Traverse all member variables.
303 unsigned FieldNo = 0;
304 for (CXXRecordDecl::field_iterator I = Info->Class->field_begin(),
305 E = Info->Class->field_end(); I != E; ++I, ++FieldNo) {
309 CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
310 UpdateEmptyFieldSubobjects(*I, FieldOffset);
314 bool EmptySubobjectMap::CanPlaceBaseAtOffset(const BaseSubobjectInfo *Info,
316 // If we know this class doesn't have any empty subobjects we don't need to
318 if (SizeOfLargestEmptySubobject.isZero())
321 if (!CanPlaceBaseSubobjectAtOffset(Info, Offset))
324 // We are able to place the base at this offset. Make sure to update the
325 // empty base subobject map.
326 UpdateEmptyBaseSubobjects(Info, Offset, Info->Class->isEmpty());
331 EmptySubobjectMap::CanPlaceFieldSubobjectAtOffset(const CXXRecordDecl *RD,
332 const CXXRecordDecl *Class,
333 CharUnits Offset) const {
334 // We don't have to keep looking past the maximum offset that's known to
335 // contain an empty class.
336 if (!AnyEmptySubobjectsBeyondOffset(Offset))
339 if (!CanPlaceSubobjectAtOffset(RD, Offset))
342 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
344 // Traverse all non-virtual bases.
345 for (const CXXBaseSpecifier &Base : RD->bases()) {
346 if (Base.isVirtual())
349 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
351 CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(BaseDecl);
352 if (!CanPlaceFieldSubobjectAtOffset(BaseDecl, Class, BaseOffset))
357 // This is the most derived class, traverse virtual bases as well.
358 for (const CXXBaseSpecifier &Base : RD->vbases()) {
359 const CXXRecordDecl *VBaseDecl = Base.getType()->getAsCXXRecordDecl();
361 CharUnits VBaseOffset = Offset + Layout.getVBaseClassOffset(VBaseDecl);
362 if (!CanPlaceFieldSubobjectAtOffset(VBaseDecl, Class, VBaseOffset))
367 // Traverse all member variables.
368 unsigned FieldNo = 0;
369 for (CXXRecordDecl::field_iterator I = RD->field_begin(), E = RD->field_end();
370 I != E; ++I, ++FieldNo) {
374 CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
376 if (!CanPlaceFieldSubobjectAtOffset(*I, FieldOffset))
384 EmptySubobjectMap::CanPlaceFieldSubobjectAtOffset(const FieldDecl *FD,
385 CharUnits Offset) const {
386 // We don't have to keep looking past the maximum offset that's known to
387 // contain an empty class.
388 if (!AnyEmptySubobjectsBeyondOffset(Offset))
391 QualType T = FD->getType();
392 if (const CXXRecordDecl *RD = T->getAsCXXRecordDecl())
393 return CanPlaceFieldSubobjectAtOffset(RD, RD, Offset);
395 // If we have an array type we need to look at every element.
396 if (const ConstantArrayType *AT = Context.getAsConstantArrayType(T)) {
397 QualType ElemTy = Context.getBaseElementType(AT);
398 const RecordType *RT = ElemTy->getAs<RecordType>();
402 const CXXRecordDecl *RD = RT->getAsCXXRecordDecl();
403 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
405 uint64_t NumElements = Context.getConstantArrayElementCount(AT);
406 CharUnits ElementOffset = Offset;
407 for (uint64_t I = 0; I != NumElements; ++I) {
408 // We don't have to keep looking past the maximum offset that's known to
409 // contain an empty class.
410 if (!AnyEmptySubobjectsBeyondOffset(ElementOffset))
413 if (!CanPlaceFieldSubobjectAtOffset(RD, RD, ElementOffset))
416 ElementOffset += Layout.getSize();
424 EmptySubobjectMap::CanPlaceFieldAtOffset(const FieldDecl *FD,
426 if (!CanPlaceFieldSubobjectAtOffset(FD, Offset))
429 // We are able to place the member variable at this offset.
430 // Make sure to update the empty base subobject map.
431 UpdateEmptyFieldSubobjects(FD, Offset);
435 void EmptySubobjectMap::UpdateEmptyFieldSubobjects(const CXXRecordDecl *RD,
436 const CXXRecordDecl *Class,
438 // We know that the only empty subobjects that can conflict with empty
439 // field subobjects are subobjects of empty bases that can be placed at offset
440 // zero. Because of this, we only need to keep track of empty field
441 // subobjects with offsets less than the size of the largest empty
442 // subobject for our class.
443 if (Offset >= SizeOfLargestEmptySubobject)
446 AddSubobjectAtOffset(RD, Offset);
448 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
450 // Traverse all non-virtual bases.
451 for (const CXXBaseSpecifier &Base : RD->bases()) {
452 if (Base.isVirtual())
455 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
457 CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(BaseDecl);
458 UpdateEmptyFieldSubobjects(BaseDecl, Class, BaseOffset);
462 // This is the most derived class, traverse virtual bases as well.
463 for (const CXXBaseSpecifier &Base : RD->vbases()) {
464 const CXXRecordDecl *VBaseDecl = Base.getType()->getAsCXXRecordDecl();
466 CharUnits VBaseOffset = Offset + Layout.getVBaseClassOffset(VBaseDecl);
467 UpdateEmptyFieldSubobjects(VBaseDecl, Class, VBaseOffset);
471 // Traverse all member variables.
472 unsigned FieldNo = 0;
473 for (CXXRecordDecl::field_iterator I = RD->field_begin(), E = RD->field_end();
474 I != E; ++I, ++FieldNo) {
478 CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
480 UpdateEmptyFieldSubobjects(*I, FieldOffset);
484 void EmptySubobjectMap::UpdateEmptyFieldSubobjects(const FieldDecl *FD,
486 QualType T = FD->getType();
487 if (const CXXRecordDecl *RD = T->getAsCXXRecordDecl()) {
488 UpdateEmptyFieldSubobjects(RD, RD, Offset);
492 // If we have an array type we need to update every element.
493 if (const ConstantArrayType *AT = Context.getAsConstantArrayType(T)) {
494 QualType ElemTy = Context.getBaseElementType(AT);
495 const RecordType *RT = ElemTy->getAs<RecordType>();
499 const CXXRecordDecl *RD = RT->getAsCXXRecordDecl();
500 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
502 uint64_t NumElements = Context.getConstantArrayElementCount(AT);
503 CharUnits ElementOffset = Offset;
505 for (uint64_t I = 0; I != NumElements; ++I) {
506 // We know that the only empty subobjects that can conflict with empty
507 // field subobjects are subobjects of empty bases that can be placed at
508 // offset zero. Because of this, we only need to keep track of empty field
509 // subobjects with offsets less than the size of the largest empty
510 // subobject for our class.
511 if (ElementOffset >= SizeOfLargestEmptySubobject)
514 UpdateEmptyFieldSubobjects(RD, RD, ElementOffset);
515 ElementOffset += Layout.getSize();
520 typedef llvm::SmallPtrSet<const CXXRecordDecl*, 4> ClassSetTy;
522 class RecordLayoutBuilder {
524 // FIXME: Remove this and make the appropriate fields public.
525 friend class clang::ASTContext;
527 const ASTContext &Context;
529 EmptySubobjectMap *EmptySubobjects;
531 /// Size - The current size of the record layout.
534 /// Alignment - The current alignment of the record layout.
537 /// \brief The alignment if attribute packed is not used.
538 CharUnits UnpackedAlignment;
540 SmallVector<uint64_t, 16> FieldOffsets;
542 /// \brief Whether the external AST source has provided a layout for this
544 unsigned ExternalLayout : 1;
546 /// \brief Whether we need to infer alignment, even when we have an
547 /// externally-provided layout.
548 unsigned InferAlignment : 1;
550 /// Packed - Whether the record is packed or not.
553 unsigned IsUnion : 1;
555 unsigned IsMac68kAlign : 1;
557 unsigned IsMsStruct : 1;
559 /// UnfilledBitsInLastUnit - If the last field laid out was a bitfield,
560 /// this contains the number of bits in the last unit that can be used for
561 /// an adjacent bitfield if necessary. The unit in question is usually
562 /// a byte, but larger units are used if IsMsStruct.
563 unsigned char UnfilledBitsInLastUnit;
564 /// LastBitfieldTypeSize - If IsMsStruct, represents the size of the type
565 /// of the previous field if it was a bitfield.
566 unsigned char LastBitfieldTypeSize;
568 /// MaxFieldAlignment - The maximum allowed field alignment. This is set by
570 CharUnits MaxFieldAlignment;
572 /// DataSize - The data size of the record being laid out.
575 CharUnits NonVirtualSize;
576 CharUnits NonVirtualAlignment;
578 /// PrimaryBase - the primary base class (if one exists) of the class
579 /// we're laying out.
580 const CXXRecordDecl *PrimaryBase;
582 /// PrimaryBaseIsVirtual - Whether the primary base of the class we're laying
584 bool PrimaryBaseIsVirtual;
586 /// HasOwnVFPtr - Whether the class provides its own vtable/vftbl
587 /// pointer, as opposed to inheriting one from a primary base class.
590 typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsetsMapTy;
592 /// Bases - base classes and their offsets in the record.
593 BaseOffsetsMapTy Bases;
595 // VBases - virtual base classes and their offsets in the record.
596 ASTRecordLayout::VBaseOffsetsMapTy VBases;
598 /// IndirectPrimaryBases - Virtual base classes, direct or indirect, that are
599 /// primary base classes for some other direct or indirect base class.
600 CXXIndirectPrimaryBaseSet IndirectPrimaryBases;
602 /// FirstNearlyEmptyVBase - The first nearly empty virtual base class in
603 /// inheritance graph order. Used for determining the primary base class.
604 const CXXRecordDecl *FirstNearlyEmptyVBase;
606 /// VisitedVirtualBases - A set of all the visited virtual bases, used to
607 /// avoid visiting virtual bases more than once.
608 llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBases;
610 /// \brief Externally-provided size.
611 uint64_t ExternalSize;
613 /// \brief Externally-provided alignment.
614 uint64_t ExternalAlign;
616 /// \brief Externally-provided field offsets.
617 llvm::DenseMap<const FieldDecl *, uint64_t> ExternalFieldOffsets;
619 /// \brief Externally-provided direct, non-virtual base offsets.
620 llvm::DenseMap<const CXXRecordDecl *, CharUnits> ExternalBaseOffsets;
622 /// \brief Externally-provided virtual base offsets.
623 llvm::DenseMap<const CXXRecordDecl *, CharUnits> ExternalVirtualBaseOffsets;
625 RecordLayoutBuilder(const ASTContext &Context,
626 EmptySubobjectMap *EmptySubobjects)
627 : Context(Context), EmptySubobjects(EmptySubobjects), Size(0),
628 Alignment(CharUnits::One()), UnpackedAlignment(CharUnits::One()),
629 ExternalLayout(false), InferAlignment(false),
630 Packed(false), IsUnion(false), IsMac68kAlign(false), IsMsStruct(false),
631 UnfilledBitsInLastUnit(0), LastBitfieldTypeSize(0),
632 MaxFieldAlignment(CharUnits::Zero()),
633 DataSize(0), NonVirtualSize(CharUnits::Zero()),
634 NonVirtualAlignment(CharUnits::One()),
635 PrimaryBase(nullptr), PrimaryBaseIsVirtual(false),
637 FirstNearlyEmptyVBase(nullptr) {}
639 /// Reset this RecordLayoutBuilder to a fresh state, using the given
640 /// alignment as the initial alignment. This is used for the
641 /// correct layout of vb-table pointers in MSVC.
642 void resetWithTargetAlignment(CharUnits TargetAlignment) {
643 const ASTContext &Context = this->Context;
644 EmptySubobjectMap *EmptySubobjects = this->EmptySubobjects;
645 this->~RecordLayoutBuilder();
646 new (this) RecordLayoutBuilder(Context, EmptySubobjects);
647 Alignment = UnpackedAlignment = TargetAlignment;
650 void Layout(const RecordDecl *D);
651 void Layout(const CXXRecordDecl *D);
652 void Layout(const ObjCInterfaceDecl *D);
654 void LayoutFields(const RecordDecl *D);
655 void LayoutField(const FieldDecl *D);
656 void LayoutWideBitField(uint64_t FieldSize, uint64_t TypeSize,
657 bool FieldPacked, const FieldDecl *D);
658 void LayoutBitField(const FieldDecl *D);
660 TargetCXXABI getCXXABI() const {
661 return Context.getTargetInfo().getCXXABI();
664 /// BaseSubobjectInfoAllocator - Allocator for BaseSubobjectInfo objects.
665 llvm::SpecificBumpPtrAllocator<BaseSubobjectInfo> BaseSubobjectInfoAllocator;
667 typedef llvm::DenseMap<const CXXRecordDecl *, BaseSubobjectInfo *>
668 BaseSubobjectInfoMapTy;
670 /// VirtualBaseInfo - Map from all the (direct or indirect) virtual bases
671 /// of the class we're laying out to their base subobject info.
672 BaseSubobjectInfoMapTy VirtualBaseInfo;
674 /// NonVirtualBaseInfo - Map from all the direct non-virtual bases of the
675 /// class we're laying out to their base subobject info.
676 BaseSubobjectInfoMapTy NonVirtualBaseInfo;
678 /// ComputeBaseSubobjectInfo - Compute the base subobject information for the
679 /// bases of the given class.
680 void ComputeBaseSubobjectInfo(const CXXRecordDecl *RD);
682 /// ComputeBaseSubobjectInfo - Compute the base subobject information for a
683 /// single class and all of its base classes.
684 BaseSubobjectInfo *ComputeBaseSubobjectInfo(const CXXRecordDecl *RD,
686 BaseSubobjectInfo *Derived);
688 /// DeterminePrimaryBase - Determine the primary base of the given class.
689 void DeterminePrimaryBase(const CXXRecordDecl *RD);
691 void SelectPrimaryVBase(const CXXRecordDecl *RD);
693 void EnsureVTablePointerAlignment(CharUnits UnpackedBaseAlign);
695 /// LayoutNonVirtualBases - Determines the primary base class (if any) and
696 /// lays it out. Will then proceed to lay out all non-virtual base clasess.
697 void LayoutNonVirtualBases(const CXXRecordDecl *RD);
699 /// LayoutNonVirtualBase - Lays out a single non-virtual base.
700 void LayoutNonVirtualBase(const BaseSubobjectInfo *Base);
702 void AddPrimaryVirtualBaseOffsets(const BaseSubobjectInfo *Info,
705 /// LayoutVirtualBases - Lays out all the virtual bases.
706 void LayoutVirtualBases(const CXXRecordDecl *RD,
707 const CXXRecordDecl *MostDerivedClass);
709 /// LayoutVirtualBase - Lays out a single virtual base.
710 void LayoutVirtualBase(const BaseSubobjectInfo *Base);
712 /// LayoutBase - Will lay out a base and return the offset where it was
713 /// placed, in chars.
714 CharUnits LayoutBase(const BaseSubobjectInfo *Base);
716 /// InitializeLayout - Initialize record layout for the given record decl.
717 void InitializeLayout(const Decl *D);
719 /// FinishLayout - Finalize record layout. Adjust record size based on the
721 void FinishLayout(const NamedDecl *D);
723 void UpdateAlignment(CharUnits NewAlignment, CharUnits UnpackedNewAlignment);
724 void UpdateAlignment(CharUnits NewAlignment) {
725 UpdateAlignment(NewAlignment, NewAlignment);
728 /// \brief Retrieve the externally-supplied field offset for the given
731 /// \param Field The field whose offset is being queried.
732 /// \param ComputedOffset The offset that we've computed for this field.
733 uint64_t updateExternalFieldOffset(const FieldDecl *Field,
734 uint64_t ComputedOffset);
736 void CheckFieldPadding(uint64_t Offset, uint64_t UnpaddedOffset,
737 uint64_t UnpackedOffset, unsigned UnpackedAlign,
738 bool isPacked, const FieldDecl *D);
740 DiagnosticBuilder Diag(SourceLocation Loc, unsigned DiagID);
742 CharUnits getSize() const {
743 assert(Size % Context.getCharWidth() == 0);
744 return Context.toCharUnitsFromBits(Size);
746 uint64_t getSizeInBits() const { return Size; }
748 void setSize(CharUnits NewSize) { Size = Context.toBits(NewSize); }
749 void setSize(uint64_t NewSize) { Size = NewSize; }
751 CharUnits getAligment() const { return Alignment; }
753 CharUnits getDataSize() const {
754 assert(DataSize % Context.getCharWidth() == 0);
755 return Context.toCharUnitsFromBits(DataSize);
757 uint64_t getDataSizeInBits() const { return DataSize; }
759 void setDataSize(CharUnits NewSize) { DataSize = Context.toBits(NewSize); }
760 void setDataSize(uint64_t NewSize) { DataSize = NewSize; }
762 RecordLayoutBuilder(const RecordLayoutBuilder &) LLVM_DELETED_FUNCTION;
763 void operator=(const RecordLayoutBuilder &) LLVM_DELETED_FUNCTION;
765 } // end anonymous namespace
768 RecordLayoutBuilder::SelectPrimaryVBase(const CXXRecordDecl *RD) {
769 for (const auto &I : RD->bases()) {
770 assert(!I.getType()->isDependentType() &&
771 "Cannot layout class with dependent bases.");
773 const CXXRecordDecl *Base = I.getType()->getAsCXXRecordDecl();
775 // Check if this is a nearly empty virtual base.
776 if (I.isVirtual() && Context.isNearlyEmpty(Base)) {
777 // If it's not an indirect primary base, then we've found our primary
779 if (!IndirectPrimaryBases.count(Base)) {
781 PrimaryBaseIsVirtual = true;
785 // Is this the first nearly empty virtual base?
786 if (!FirstNearlyEmptyVBase)
787 FirstNearlyEmptyVBase = Base;
790 SelectPrimaryVBase(Base);
796 /// DeterminePrimaryBase - Determine the primary base of the given class.
797 void RecordLayoutBuilder::DeterminePrimaryBase(const CXXRecordDecl *RD) {
798 // If the class isn't dynamic, it won't have a primary base.
799 if (!RD->isDynamicClass())
802 // Compute all the primary virtual bases for all of our direct and
803 // indirect bases, and record all their primary virtual base classes.
804 RD->getIndirectPrimaryBases(IndirectPrimaryBases);
806 // If the record has a dynamic base class, attempt to choose a primary base
807 // class. It is the first (in direct base class order) non-virtual dynamic
808 // base class, if one exists.
809 for (const auto &I : RD->bases()) {
810 // Ignore virtual bases.
814 const CXXRecordDecl *Base = I.getType()->getAsCXXRecordDecl();
816 if (Base->isDynamicClass()) {
819 PrimaryBaseIsVirtual = false;
824 // Under the Itanium ABI, if there is no non-virtual primary base class,
825 // try to compute the primary virtual base. The primary virtual base is
826 // the first nearly empty virtual base that is not an indirect primary
827 // virtual base class, if one exists.
828 if (RD->getNumVBases() != 0) {
829 SelectPrimaryVBase(RD);
834 // Otherwise, it is the first indirect primary base class, if one exists.
835 if (FirstNearlyEmptyVBase) {
836 PrimaryBase = FirstNearlyEmptyVBase;
837 PrimaryBaseIsVirtual = true;
841 assert(!PrimaryBase && "Should not get here with a primary base!");
845 RecordLayoutBuilder::ComputeBaseSubobjectInfo(const CXXRecordDecl *RD,
847 BaseSubobjectInfo *Derived) {
848 BaseSubobjectInfo *Info;
851 // Check if we already have info about this virtual base.
852 BaseSubobjectInfo *&InfoSlot = VirtualBaseInfo[RD];
854 assert(InfoSlot->Class == RD && "Wrong class for virtual base info!");
858 // We don't, create it.
859 InfoSlot = new (BaseSubobjectInfoAllocator.Allocate()) BaseSubobjectInfo;
862 Info = new (BaseSubobjectInfoAllocator.Allocate()) BaseSubobjectInfo;
866 Info->IsVirtual = IsVirtual;
867 Info->Derived = nullptr;
868 Info->PrimaryVirtualBaseInfo = nullptr;
870 const CXXRecordDecl *PrimaryVirtualBase = nullptr;
871 BaseSubobjectInfo *PrimaryVirtualBaseInfo = nullptr;
873 // Check if this base has a primary virtual base.
874 if (RD->getNumVBases()) {
875 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
876 if (Layout.isPrimaryBaseVirtual()) {
877 // This base does have a primary virtual base.
878 PrimaryVirtualBase = Layout.getPrimaryBase();
879 assert(PrimaryVirtualBase && "Didn't have a primary virtual base!");
881 // Now check if we have base subobject info about this primary base.
882 PrimaryVirtualBaseInfo = VirtualBaseInfo.lookup(PrimaryVirtualBase);
884 if (PrimaryVirtualBaseInfo) {
885 if (PrimaryVirtualBaseInfo->Derived) {
886 // We did have info about this primary base, and it turns out that it
887 // has already been claimed as a primary virtual base for another
889 PrimaryVirtualBase = nullptr;
891 // We can claim this base as our primary base.
892 Info->PrimaryVirtualBaseInfo = PrimaryVirtualBaseInfo;
893 PrimaryVirtualBaseInfo->Derived = Info;
899 // Now go through all direct bases.
900 for (const auto &I : RD->bases()) {
901 bool IsVirtual = I.isVirtual();
903 const CXXRecordDecl *BaseDecl = I.getType()->getAsCXXRecordDecl();
905 Info->Bases.push_back(ComputeBaseSubobjectInfo(BaseDecl, IsVirtual, Info));
908 if (PrimaryVirtualBase && !PrimaryVirtualBaseInfo) {
909 // Traversing the bases must have created the base info for our primary
911 PrimaryVirtualBaseInfo = VirtualBaseInfo.lookup(PrimaryVirtualBase);
912 assert(PrimaryVirtualBaseInfo &&
913 "Did not create a primary virtual base!");
915 // Claim the primary virtual base as our primary virtual base.
916 Info->PrimaryVirtualBaseInfo = PrimaryVirtualBaseInfo;
917 PrimaryVirtualBaseInfo->Derived = Info;
923 void RecordLayoutBuilder::ComputeBaseSubobjectInfo(const CXXRecordDecl *RD) {
924 for (const auto &I : RD->bases()) {
925 bool IsVirtual = I.isVirtual();
927 const CXXRecordDecl *BaseDecl = I.getType()->getAsCXXRecordDecl();
929 // Compute the base subobject info for this base.
930 BaseSubobjectInfo *Info = ComputeBaseSubobjectInfo(BaseDecl, IsVirtual,
934 // ComputeBaseInfo has already added this base for us.
935 assert(VirtualBaseInfo.count(BaseDecl) &&
936 "Did not add virtual base!");
938 // Add the base info to the map of non-virtual bases.
939 assert(!NonVirtualBaseInfo.count(BaseDecl) &&
940 "Non-virtual base already exists!");
941 NonVirtualBaseInfo.insert(std::make_pair(BaseDecl, Info));
947 RecordLayoutBuilder::EnsureVTablePointerAlignment(CharUnits UnpackedBaseAlign) {
948 CharUnits BaseAlign = (Packed) ? CharUnits::One() : UnpackedBaseAlign;
950 // The maximum field alignment overrides base align.
951 if (!MaxFieldAlignment.isZero()) {
952 BaseAlign = std::min(BaseAlign, MaxFieldAlignment);
953 UnpackedBaseAlign = std::min(UnpackedBaseAlign, MaxFieldAlignment);
956 // Round up the current record size to pointer alignment.
957 setSize(getSize().RoundUpToAlignment(BaseAlign));
958 setDataSize(getSize());
960 // Update the alignment.
961 UpdateAlignment(BaseAlign, UnpackedBaseAlign);
965 RecordLayoutBuilder::LayoutNonVirtualBases(const CXXRecordDecl *RD) {
966 // Then, determine the primary base class.
967 DeterminePrimaryBase(RD);
969 // Compute base subobject info.
970 ComputeBaseSubobjectInfo(RD);
972 // If we have a primary base class, lay it out.
974 if (PrimaryBaseIsVirtual) {
975 // If the primary virtual base was a primary virtual base of some other
976 // base class we'll have to steal it.
977 BaseSubobjectInfo *PrimaryBaseInfo = VirtualBaseInfo.lookup(PrimaryBase);
978 PrimaryBaseInfo->Derived = nullptr;
980 // We have a virtual primary base, insert it as an indirect primary base.
981 IndirectPrimaryBases.insert(PrimaryBase);
983 assert(!VisitedVirtualBases.count(PrimaryBase) &&
984 "vbase already visited!");
985 VisitedVirtualBases.insert(PrimaryBase);
987 LayoutVirtualBase(PrimaryBaseInfo);
989 BaseSubobjectInfo *PrimaryBaseInfo =
990 NonVirtualBaseInfo.lookup(PrimaryBase);
991 assert(PrimaryBaseInfo &&
992 "Did not find base info for non-virtual primary base!");
994 LayoutNonVirtualBase(PrimaryBaseInfo);
997 // If this class needs a vtable/vf-table and didn't get one from a
998 // primary base, add it in now.
999 } else if (RD->isDynamicClass()) {
1000 assert(DataSize == 0 && "Vtable pointer must be at offset zero!");
1001 CharUnits PtrWidth =
1002 Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
1003 CharUnits PtrAlign =
1004 Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerAlign(0));
1005 EnsureVTablePointerAlignment(PtrAlign);
1007 setSize(getSize() + PtrWidth);
1008 setDataSize(getSize());
1011 // Now lay out the non-virtual bases.
1012 for (const auto &I : RD->bases()) {
1014 // Ignore virtual bases.
1018 const CXXRecordDecl *BaseDecl = I.getType()->getAsCXXRecordDecl();
1020 // Skip the primary base, because we've already laid it out. The
1021 // !PrimaryBaseIsVirtual check is required because we might have a
1022 // non-virtual base of the same type as a primary virtual base.
1023 if (BaseDecl == PrimaryBase && !PrimaryBaseIsVirtual)
1026 // Lay out the base.
1027 BaseSubobjectInfo *BaseInfo = NonVirtualBaseInfo.lookup(BaseDecl);
1028 assert(BaseInfo && "Did not find base info for non-virtual base!");
1030 LayoutNonVirtualBase(BaseInfo);
1034 void RecordLayoutBuilder::LayoutNonVirtualBase(const BaseSubobjectInfo *Base) {
1036 CharUnits Offset = LayoutBase(Base);
1038 // Add its base class offset.
1039 assert(!Bases.count(Base->Class) && "base offset already exists!");
1040 Bases.insert(std::make_pair(Base->Class, Offset));
1042 AddPrimaryVirtualBaseOffsets(Base, Offset);
1046 RecordLayoutBuilder::AddPrimaryVirtualBaseOffsets(const BaseSubobjectInfo *Info,
1048 // This base isn't interesting, it has no virtual bases.
1049 if (!Info->Class->getNumVBases())
1052 // First, check if we have a virtual primary base to add offsets for.
1053 if (Info->PrimaryVirtualBaseInfo) {
1054 assert(Info->PrimaryVirtualBaseInfo->IsVirtual &&
1055 "Primary virtual base is not virtual!");
1056 if (Info->PrimaryVirtualBaseInfo->Derived == Info) {
1058 assert(!VBases.count(Info->PrimaryVirtualBaseInfo->Class) &&
1059 "primary vbase offset already exists!");
1060 VBases.insert(std::make_pair(Info->PrimaryVirtualBaseInfo->Class,
1061 ASTRecordLayout::VBaseInfo(Offset, false)));
1063 // Traverse the primary virtual base.
1064 AddPrimaryVirtualBaseOffsets(Info->PrimaryVirtualBaseInfo, Offset);
1068 // Now go through all direct non-virtual bases.
1069 const ASTRecordLayout &Layout = Context.getASTRecordLayout(Info->Class);
1070 for (const BaseSubobjectInfo *Base : Info->Bases) {
1071 if (Base->IsVirtual)
1074 CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base->Class);
1075 AddPrimaryVirtualBaseOffsets(Base, BaseOffset);
1080 RecordLayoutBuilder::LayoutVirtualBases(const CXXRecordDecl *RD,
1081 const CXXRecordDecl *MostDerivedClass) {
1082 const CXXRecordDecl *PrimaryBase;
1083 bool PrimaryBaseIsVirtual;
1085 if (MostDerivedClass == RD) {
1086 PrimaryBase = this->PrimaryBase;
1087 PrimaryBaseIsVirtual = this->PrimaryBaseIsVirtual;
1089 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1090 PrimaryBase = Layout.getPrimaryBase();
1091 PrimaryBaseIsVirtual = Layout.isPrimaryBaseVirtual();
1094 for (const CXXBaseSpecifier &Base : RD->bases()) {
1095 assert(!Base.getType()->isDependentType() &&
1096 "Cannot layout class with dependent bases.");
1098 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
1100 if (Base.isVirtual()) {
1101 if (PrimaryBase != BaseDecl || !PrimaryBaseIsVirtual) {
1102 bool IndirectPrimaryBase = IndirectPrimaryBases.count(BaseDecl);
1104 // Only lay out the virtual base if it's not an indirect primary base.
1105 if (!IndirectPrimaryBase) {
1106 // Only visit virtual bases once.
1107 if (!VisitedVirtualBases.insert(BaseDecl))
1110 const BaseSubobjectInfo *BaseInfo = VirtualBaseInfo.lookup(BaseDecl);
1111 assert(BaseInfo && "Did not find virtual base info!");
1112 LayoutVirtualBase(BaseInfo);
1117 if (!BaseDecl->getNumVBases()) {
1118 // This base isn't interesting since it doesn't have any virtual bases.
1122 LayoutVirtualBases(BaseDecl, MostDerivedClass);
1126 void RecordLayoutBuilder::LayoutVirtualBase(const BaseSubobjectInfo *Base) {
1127 assert(!Base->Derived && "Trying to lay out a primary virtual base!");
1130 CharUnits Offset = LayoutBase(Base);
1132 // Add its base class offset.
1133 assert(!VBases.count(Base->Class) && "vbase offset already exists!");
1134 VBases.insert(std::make_pair(Base->Class,
1135 ASTRecordLayout::VBaseInfo(Offset, false)));
1137 AddPrimaryVirtualBaseOffsets(Base, Offset);
1140 CharUnits RecordLayoutBuilder::LayoutBase(const BaseSubobjectInfo *Base) {
1141 const ASTRecordLayout &Layout = Context.getASTRecordLayout(Base->Class);
1146 // Query the external layout to see if it provides an offset.
1147 bool HasExternalLayout = false;
1148 if (ExternalLayout) {
1149 llvm::DenseMap<const CXXRecordDecl *, CharUnits>::iterator Known;
1150 if (Base->IsVirtual) {
1151 Known = ExternalVirtualBaseOffsets.find(Base->Class);
1152 if (Known != ExternalVirtualBaseOffsets.end()) {
1153 Offset = Known->second;
1154 HasExternalLayout = true;
1157 Known = ExternalBaseOffsets.find(Base->Class);
1158 if (Known != ExternalBaseOffsets.end()) {
1159 Offset = Known->second;
1160 HasExternalLayout = true;
1165 CharUnits UnpackedBaseAlign = Layout.getNonVirtualAlignment();
1166 CharUnits BaseAlign = (Packed) ? CharUnits::One() : UnpackedBaseAlign;
1168 // If we have an empty base class, try to place it at offset 0.
1169 if (Base->Class->isEmpty() &&
1170 (!HasExternalLayout || Offset == CharUnits::Zero()) &&
1171 EmptySubobjects->CanPlaceBaseAtOffset(Base, CharUnits::Zero())) {
1172 setSize(std::max(getSize(), Layout.getSize()));
1173 UpdateAlignment(BaseAlign, UnpackedBaseAlign);
1175 return CharUnits::Zero();
1178 // The maximum field alignment overrides base align.
1179 if (!MaxFieldAlignment.isZero()) {
1180 BaseAlign = std::min(BaseAlign, MaxFieldAlignment);
1181 UnpackedBaseAlign = std::min(UnpackedBaseAlign, MaxFieldAlignment);
1184 if (!HasExternalLayout) {
1185 // Round up the current record size to the base's alignment boundary.
1186 Offset = getDataSize().RoundUpToAlignment(BaseAlign);
1188 // Try to place the base.
1189 while (!EmptySubobjects->CanPlaceBaseAtOffset(Base, Offset))
1190 Offset += BaseAlign;
1192 bool Allowed = EmptySubobjects->CanPlaceBaseAtOffset(Base, Offset);
1194 assert(Allowed && "Base subobject externally placed at overlapping offset");
1196 if (InferAlignment && Offset < getDataSize().RoundUpToAlignment(BaseAlign)){
1197 // The externally-supplied base offset is before the base offset we
1198 // computed. Assume that the structure is packed.
1199 Alignment = CharUnits::One();
1200 InferAlignment = false;
1204 if (!Base->Class->isEmpty()) {
1205 // Update the data size.
1206 setDataSize(Offset + Layout.getNonVirtualSize());
1208 setSize(std::max(getSize(), getDataSize()));
1210 setSize(std::max(getSize(), Offset + Layout.getSize()));
1212 // Remember max struct/class alignment.
1213 UpdateAlignment(BaseAlign, UnpackedBaseAlign);
1218 void RecordLayoutBuilder::InitializeLayout(const Decl *D) {
1219 if (const RecordDecl *RD = dyn_cast<RecordDecl>(D)) {
1220 IsUnion = RD->isUnion();
1221 IsMsStruct = RD->isMsStruct(Context);
1224 Packed = D->hasAttr<PackedAttr>();
1226 // Honor the default struct packing maximum alignment flag.
1227 if (unsigned DefaultMaxFieldAlignment = Context.getLangOpts().PackStruct) {
1228 MaxFieldAlignment = CharUnits::fromQuantity(DefaultMaxFieldAlignment);
1231 // mac68k alignment supersedes maximum field alignment and attribute aligned,
1232 // and forces all structures to have 2-byte alignment. The IBM docs on it
1233 // allude to additional (more complicated) semantics, especially with regard
1234 // to bit-fields, but gcc appears not to follow that.
1235 if (D->hasAttr<AlignMac68kAttr>()) {
1236 IsMac68kAlign = true;
1237 MaxFieldAlignment = CharUnits::fromQuantity(2);
1238 Alignment = CharUnits::fromQuantity(2);
1240 if (const MaxFieldAlignmentAttr *MFAA = D->getAttr<MaxFieldAlignmentAttr>())
1241 MaxFieldAlignment = Context.toCharUnitsFromBits(MFAA->getAlignment());
1243 if (unsigned MaxAlign = D->getMaxAlignment())
1244 UpdateAlignment(Context.toCharUnitsFromBits(MaxAlign));
1247 // If there is an external AST source, ask it for the various offsets.
1248 if (const RecordDecl *RD = dyn_cast<RecordDecl>(D))
1249 if (ExternalASTSource *External = Context.getExternalSource()) {
1250 ExternalLayout = External->layoutRecordType(RD,
1253 ExternalFieldOffsets,
1254 ExternalBaseOffsets,
1255 ExternalVirtualBaseOffsets);
1257 // Update based on external alignment.
1258 if (ExternalLayout) {
1259 if (ExternalAlign > 0) {
1260 Alignment = Context.toCharUnitsFromBits(ExternalAlign);
1262 // The external source didn't have alignment information; infer it.
1263 InferAlignment = true;
1269 void RecordLayoutBuilder::Layout(const RecordDecl *D) {
1270 InitializeLayout(D);
1273 // Finally, round the size of the total struct up to the alignment of the
1278 void RecordLayoutBuilder::Layout(const CXXRecordDecl *RD) {
1279 InitializeLayout(RD);
1281 // Lay out the vtable and the non-virtual bases.
1282 LayoutNonVirtualBases(RD);
1286 NonVirtualSize = Context.toCharUnitsFromBits(
1287 llvm::RoundUpToAlignment(getSizeInBits(),
1288 Context.getTargetInfo().getCharAlign()));
1289 NonVirtualAlignment = Alignment;
1291 // Lay out the virtual bases and add the primary virtual base offsets.
1292 LayoutVirtualBases(RD, RD);
1294 // Finally, round the size of the total struct up to the alignment
1295 // of the struct itself.
1299 // Check that we have base offsets for all bases.
1300 for (const CXXBaseSpecifier &Base : RD->bases()) {
1301 if (Base.isVirtual())
1304 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
1306 assert(Bases.count(BaseDecl) && "Did not find base offset!");
1309 // And all virtual bases.
1310 for (const CXXBaseSpecifier &Base : RD->vbases()) {
1311 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
1313 assert(VBases.count(BaseDecl) && "Did not find base offset!");
1318 void RecordLayoutBuilder::Layout(const ObjCInterfaceDecl *D) {
1319 if (ObjCInterfaceDecl *SD = D->getSuperClass()) {
1320 const ASTRecordLayout &SL = Context.getASTObjCInterfaceLayout(SD);
1322 UpdateAlignment(SL.getAlignment());
1324 // We start laying out ivars not at the end of the superclass
1325 // structure, but at the next byte following the last field.
1326 setSize(SL.getDataSize());
1327 setDataSize(getSize());
1330 InitializeLayout(D);
1331 // Layout each ivar sequentially.
1332 for (const ObjCIvarDecl *IVD = D->all_declared_ivar_begin(); IVD;
1333 IVD = IVD->getNextIvar())
1336 // Finally, round the size of the total struct up to the alignment of the
1341 void RecordLayoutBuilder::LayoutFields(const RecordDecl *D) {
1342 // Layout each field, for now, just sequentially, respecting alignment. In
1343 // the future, this will need to be tweakable by targets.
1344 for (const auto *Field : D->fields())
1348 void RecordLayoutBuilder::LayoutWideBitField(uint64_t FieldSize,
1351 const FieldDecl *D) {
1352 assert(Context.getLangOpts().CPlusPlus &&
1353 "Can only have wide bit-fields in C++!");
1355 // Itanium C++ ABI 2.4:
1356 // If sizeof(T)*8 < n, let T' be the largest integral POD type with
1357 // sizeof(T')*8 <= n.
1359 QualType IntegralPODTypes[] = {
1360 Context.UnsignedCharTy, Context.UnsignedShortTy, Context.UnsignedIntTy,
1361 Context.UnsignedLongTy, Context.UnsignedLongLongTy
1365 for (const QualType &QT : IntegralPODTypes) {
1366 uint64_t Size = Context.getTypeSize(QT);
1368 if (Size > FieldSize)
1373 assert(!Type.isNull() && "Did not find a type!");
1375 CharUnits TypeAlign = Context.getTypeAlignInChars(Type);
1377 // We're not going to use any of the unfilled bits in the last byte.
1378 UnfilledBitsInLastUnit = 0;
1379 LastBitfieldTypeSize = 0;
1381 uint64_t FieldOffset;
1382 uint64_t UnpaddedFieldOffset = getDataSizeInBits() - UnfilledBitsInLastUnit;
1385 setDataSize(std::max(getDataSizeInBits(), FieldSize));
1388 // The bitfield is allocated starting at the next offset aligned
1389 // appropriately for T', with length n bits.
1390 FieldOffset = llvm::RoundUpToAlignment(getDataSizeInBits(),
1391 Context.toBits(TypeAlign));
1393 uint64_t NewSizeInBits = FieldOffset + FieldSize;
1395 setDataSize(llvm::RoundUpToAlignment(NewSizeInBits,
1396 Context.getTargetInfo().getCharAlign()));
1397 UnfilledBitsInLastUnit = getDataSizeInBits() - NewSizeInBits;
1400 // Place this field at the current location.
1401 FieldOffsets.push_back(FieldOffset);
1403 CheckFieldPadding(FieldOffset, UnpaddedFieldOffset, FieldOffset,
1404 Context.toBits(TypeAlign), FieldPacked, D);
1407 setSize(std::max(getSizeInBits(), getDataSizeInBits()));
1409 // Remember max struct/class alignment.
1410 UpdateAlignment(TypeAlign);
1413 void RecordLayoutBuilder::LayoutBitField(const FieldDecl *D) {
1414 bool FieldPacked = Packed || D->hasAttr<PackedAttr>();
1415 uint64_t FieldSize = D->getBitWidthValue(Context);
1416 std::pair<uint64_t, unsigned> FieldInfo = Context.getTypeInfo(D->getType());
1417 uint64_t TypeSize = FieldInfo.first;
1418 unsigned FieldAlign = FieldInfo.second;
1420 // UnfilledBitsInLastUnit is the difference between the end of the
1421 // last allocated bitfield (i.e. the first bit offset available for
1422 // bitfields) and the end of the current data size in bits (i.e. the
1423 // first bit offset available for non-bitfields). The current data
1424 // size in bits is always a multiple of the char size; additionally,
1425 // for ms_struct records it's also a multiple of the
1426 // LastBitfieldTypeSize (if set).
1428 // The struct-layout algorithm is dictated by the platform ABI,
1429 // which in principle could use almost any rules it likes. In
1430 // practice, UNIXy targets tend to inherit the algorithm described
1431 // in the System V generic ABI. The basic bitfield layout rule in
1432 // System V is to place bitfields at the next available bit offset
1433 // where the entire bitfield would fit in an aligned storage unit of
1434 // the declared type; it's okay if an earlier or later non-bitfield
1435 // is allocated in the same storage unit. However, some targets
1436 // (those that !useBitFieldTypeAlignment(), e.g. ARM APCS) don't
1437 // require this storage unit to be aligned, and therefore always put
1438 // the bitfield at the next available bit offset.
1440 // ms_struct basically requests a complete replacement of the
1441 // platform ABI's struct-layout algorithm, with the high-level goal
1442 // of duplicating MSVC's layout. For non-bitfields, this follows
1443 // the the standard algorithm. The basic bitfield layout rule is to
1444 // allocate an entire unit of the bitfield's declared type
1445 // (e.g. 'unsigned long'), then parcel it up among successive
1446 // bitfields whose declared types have the same size, making a new
1447 // unit as soon as the last can no longer store the whole value.
1448 // Since it completely replaces the platform ABI's algorithm,
1449 // settings like !useBitFieldTypeAlignment() do not apply.
1451 // A zero-width bitfield forces the use of a new storage unit for
1452 // later bitfields. In general, this occurs by rounding up the
1453 // current size of the struct as if the algorithm were about to
1454 // place a non-bitfield of the field's formal type. Usually this
1455 // does not change the alignment of the struct itself, but it does
1456 // on some targets (those that useZeroLengthBitfieldAlignment(),
1457 // e.g. ARM). In ms_struct layout, zero-width bitfields are
1458 // ignored unless they follow a non-zero-width bitfield.
1460 // A field alignment restriction (e.g. from #pragma pack) or
1461 // specification (e.g. from __attribute__((aligned))) changes the
1462 // formal alignment of the field. For System V, this alters the
1463 // required alignment of the notional storage unit that must contain
1464 // the bitfield. For ms_struct, this only affects the placement of
1465 // new storage units. In both cases, the effect of #pragma pack is
1466 // ignored on zero-width bitfields.
1468 // On System V, a packed field (e.g. from #pragma pack or
1469 // __attribute__((packed))) always uses the next available bit
1472 // In an ms_struct struct, the alignment of a fundamental type is
1473 // always equal to its size. This is necessary in order to mimic
1474 // the i386 alignment rules on targets which might not fully align
1475 // all types (e.g. Darwin PPC32, where alignof(long long) == 4).
1477 // First, some simple bookkeeping to perform for ms_struct structs.
1479 // The field alignment for integer types is always the size.
1480 FieldAlign = TypeSize;
1482 // If the previous field was not a bitfield, or was a bitfield
1483 // with a different storage unit size, we're done with that
1485 if (LastBitfieldTypeSize != TypeSize) {
1486 // Also, ignore zero-length bitfields after non-bitfields.
1487 if (!LastBitfieldTypeSize && !FieldSize)
1490 UnfilledBitsInLastUnit = 0;
1491 LastBitfieldTypeSize = 0;
1495 // If the field is wider than its declared type, it follows
1496 // different rules in all cases.
1497 if (FieldSize > TypeSize) {
1498 LayoutWideBitField(FieldSize, TypeSize, FieldPacked, D);
1502 // Compute the next available bit offset.
1503 uint64_t FieldOffset =
1504 IsUnion ? 0 : (getDataSizeInBits() - UnfilledBitsInLastUnit);
1506 // Handle targets that don't honor bitfield type alignment.
1507 if (!IsMsStruct && !Context.getTargetInfo().useBitFieldTypeAlignment()) {
1508 // Some such targets do honor it on zero-width bitfields.
1509 if (FieldSize == 0 &&
1510 Context.getTargetInfo().useZeroLengthBitfieldAlignment()) {
1511 // The alignment to round up to is the max of the field's natural
1512 // alignment and a target-specific fixed value (sometimes zero).
1513 unsigned ZeroLengthBitfieldBoundary =
1514 Context.getTargetInfo().getZeroLengthBitfieldBoundary();
1515 FieldAlign = std::max(FieldAlign, ZeroLengthBitfieldBoundary);
1517 // If that doesn't apply, just ignore the field alignment.
1523 // Remember the alignment we would have used if the field were not packed.
1524 unsigned UnpackedFieldAlign = FieldAlign;
1526 // Ignore the field alignment if the field is packed unless it has zero-size.
1527 if (!IsMsStruct && FieldPacked && FieldSize != 0)
1530 // But, if there's an 'aligned' attribute on the field, honor that.
1531 if (unsigned ExplicitFieldAlign = D->getMaxAlignment()) {
1532 FieldAlign = std::max(FieldAlign, ExplicitFieldAlign);
1533 UnpackedFieldAlign = std::max(UnpackedFieldAlign, ExplicitFieldAlign);
1536 // But, if there's a #pragma pack in play, that takes precedent over
1537 // even the 'aligned' attribute, for non-zero-width bitfields.
1538 if (!MaxFieldAlignment.isZero() && FieldSize) {
1539 unsigned MaxFieldAlignmentInBits = Context.toBits(MaxFieldAlignment);
1540 FieldAlign = std::min(FieldAlign, MaxFieldAlignmentInBits);
1541 UnpackedFieldAlign = std::min(UnpackedFieldAlign, MaxFieldAlignmentInBits);
1544 // For purposes of diagnostics, we're going to simultaneously
1545 // compute the field offsets that we would have used if we weren't
1546 // adding any alignment padding or if the field weren't packed.
1547 uint64_t UnpaddedFieldOffset = FieldOffset;
1548 uint64_t UnpackedFieldOffset = FieldOffset;
1550 // Check if we need to add padding to fit the bitfield within an
1551 // allocation unit with the right size and alignment. The rules are
1552 // somewhat different here for ms_struct structs.
1554 // If it's not a zero-width bitfield, and we can fit the bitfield
1555 // into the active storage unit (and we haven't already decided to
1556 // start a new storage unit), just do so, regardless of any other
1557 // other consideration. Otherwise, round up to the right alignment.
1558 if (FieldSize == 0 || FieldSize > UnfilledBitsInLastUnit) {
1559 FieldOffset = llvm::RoundUpToAlignment(FieldOffset, FieldAlign);
1560 UnpackedFieldOffset = llvm::RoundUpToAlignment(UnpackedFieldOffset,
1561 UnpackedFieldAlign);
1562 UnfilledBitsInLastUnit = 0;
1566 // #pragma pack, with any value, suppresses the insertion of padding.
1567 bool AllowPadding = MaxFieldAlignment.isZero();
1569 // Compute the real offset.
1570 if (FieldSize == 0 ||
1572 (FieldOffset & (FieldAlign-1)) + FieldSize > TypeSize)) {
1573 FieldOffset = llvm::RoundUpToAlignment(FieldOffset, FieldAlign);
1576 // Repeat the computation for diagnostic purposes.
1577 if (FieldSize == 0 ||
1579 (UnpackedFieldOffset & (UnpackedFieldAlign-1)) + FieldSize > TypeSize))
1580 UnpackedFieldOffset = llvm::RoundUpToAlignment(UnpackedFieldOffset,
1581 UnpackedFieldAlign);
1584 // If we're using external layout, give the external layout a chance
1585 // to override this information.
1587 FieldOffset = updateExternalFieldOffset(D, FieldOffset);
1589 // Okay, place the bitfield at the calculated offset.
1590 FieldOffsets.push_back(FieldOffset);
1594 // Anonymous members don't affect the overall record alignment,
1595 // except on targets where they do.
1597 !Context.getTargetInfo().useZeroLengthBitfieldAlignment() &&
1598 !D->getIdentifier())
1599 FieldAlign = UnpackedFieldAlign = 1;
1601 // Diagnose differences in layout due to padding or packing.
1602 if (!ExternalLayout)
1603 CheckFieldPadding(FieldOffset, UnpaddedFieldOffset, UnpackedFieldOffset,
1604 UnpackedFieldAlign, FieldPacked, D);
1606 // Update DataSize to include the last byte containing (part of) the bitfield.
1608 // For unions, this is just a max operation, as usual.
1610 // FIXME: I think FieldSize should be TypeSize here.
1611 setDataSize(std::max(getDataSizeInBits(), FieldSize));
1613 // For non-zero-width bitfields in ms_struct structs, allocate a new
1614 // storage unit if necessary.
1615 } else if (IsMsStruct && FieldSize) {
1616 // We should have cleared UnfilledBitsInLastUnit in every case
1617 // where we changed storage units.
1618 if (!UnfilledBitsInLastUnit) {
1619 setDataSize(FieldOffset + TypeSize);
1620 UnfilledBitsInLastUnit = TypeSize;
1622 UnfilledBitsInLastUnit -= FieldSize;
1623 LastBitfieldTypeSize = TypeSize;
1625 // Otherwise, bump the data size up to include the bitfield,
1626 // including padding up to char alignment, and then remember how
1627 // bits we didn't use.
1629 uint64_t NewSizeInBits = FieldOffset + FieldSize;
1630 uint64_t CharAlignment = Context.getTargetInfo().getCharAlign();
1631 setDataSize(llvm::RoundUpToAlignment(NewSizeInBits, CharAlignment));
1632 UnfilledBitsInLastUnit = getDataSizeInBits() - NewSizeInBits;
1634 // The only time we can get here for an ms_struct is if this is a
1635 // zero-width bitfield, which doesn't count as anything for the
1636 // purposes of unfilled bits.
1637 LastBitfieldTypeSize = 0;
1641 setSize(std::max(getSizeInBits(), getDataSizeInBits()));
1643 // Remember max struct/class alignment.
1644 UpdateAlignment(Context.toCharUnitsFromBits(FieldAlign),
1645 Context.toCharUnitsFromBits(UnpackedFieldAlign));
1648 void RecordLayoutBuilder::LayoutField(const FieldDecl *D) {
1649 if (D->isBitField()) {
1654 uint64_t UnpaddedFieldOffset = getDataSizeInBits() - UnfilledBitsInLastUnit;
1656 // Reset the unfilled bits.
1657 UnfilledBitsInLastUnit = 0;
1658 LastBitfieldTypeSize = 0;
1660 bool FieldPacked = Packed || D->hasAttr<PackedAttr>();
1661 CharUnits FieldOffset =
1662 IsUnion ? CharUnits::Zero() : getDataSize();
1663 CharUnits FieldSize;
1664 CharUnits FieldAlign;
1666 if (D->getType()->isIncompleteArrayType()) {
1667 // This is a flexible array member; we can't directly
1668 // query getTypeInfo about these, so we figure it out here.
1669 // Flexible array members don't have any size, but they
1670 // have to be aligned appropriately for their element type.
1671 FieldSize = CharUnits::Zero();
1672 const ArrayType* ATy = Context.getAsArrayType(D->getType());
1673 FieldAlign = Context.getTypeAlignInChars(ATy->getElementType());
1674 } else if (const ReferenceType *RT = D->getType()->getAs<ReferenceType>()) {
1675 unsigned AS = RT->getPointeeType().getAddressSpace();
1677 Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(AS));
1679 Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerAlign(AS));
1681 std::pair<CharUnits, CharUnits> FieldInfo =
1682 Context.getTypeInfoInChars(D->getType());
1683 FieldSize = FieldInfo.first;
1684 FieldAlign = FieldInfo.second;
1687 // If MS bitfield layout is required, figure out what type is being
1688 // laid out and align the field to the width of that type.
1690 // Resolve all typedefs down to their base type and round up the field
1691 // alignment if necessary.
1692 QualType T = Context.getBaseElementType(D->getType());
1693 if (const BuiltinType *BTy = T->getAs<BuiltinType>()) {
1694 CharUnits TypeSize = Context.getTypeSizeInChars(BTy);
1695 if (TypeSize > FieldAlign)
1696 FieldAlign = TypeSize;
1701 // The align if the field is not packed. This is to check if the attribute
1702 // was unnecessary (-Wpacked).
1703 CharUnits UnpackedFieldAlign = FieldAlign;
1704 CharUnits UnpackedFieldOffset = FieldOffset;
1707 FieldAlign = CharUnits::One();
1708 CharUnits MaxAlignmentInChars =
1709 Context.toCharUnitsFromBits(D->getMaxAlignment());
1710 FieldAlign = std::max(FieldAlign, MaxAlignmentInChars);
1711 UnpackedFieldAlign = std::max(UnpackedFieldAlign, MaxAlignmentInChars);
1713 // The maximum field alignment overrides the aligned attribute.
1714 if (!MaxFieldAlignment.isZero()) {
1715 FieldAlign = std::min(FieldAlign, MaxFieldAlignment);
1716 UnpackedFieldAlign = std::min(UnpackedFieldAlign, MaxFieldAlignment);
1719 // Round up the current record size to the field's alignment boundary.
1720 FieldOffset = FieldOffset.RoundUpToAlignment(FieldAlign);
1721 UnpackedFieldOffset =
1722 UnpackedFieldOffset.RoundUpToAlignment(UnpackedFieldAlign);
1724 if (ExternalLayout) {
1725 FieldOffset = Context.toCharUnitsFromBits(
1726 updateExternalFieldOffset(D, Context.toBits(FieldOffset)));
1728 if (!IsUnion && EmptySubobjects) {
1729 // Record the fact that we're placing a field at this offset.
1730 bool Allowed = EmptySubobjects->CanPlaceFieldAtOffset(D, FieldOffset);
1732 assert(Allowed && "Externally-placed field cannot be placed here");
1735 if (!IsUnion && EmptySubobjects) {
1736 // Check if we can place the field at this offset.
1737 while (!EmptySubobjects->CanPlaceFieldAtOffset(D, FieldOffset)) {
1738 // We couldn't place the field at the offset. Try again at a new offset.
1739 FieldOffset += FieldAlign;
1744 // Place this field at the current location.
1745 FieldOffsets.push_back(Context.toBits(FieldOffset));
1747 if (!ExternalLayout)
1748 CheckFieldPadding(Context.toBits(FieldOffset), UnpaddedFieldOffset,
1749 Context.toBits(UnpackedFieldOffset),
1750 Context.toBits(UnpackedFieldAlign), FieldPacked, D);
1752 // Reserve space for this field.
1753 uint64_t FieldSizeInBits = Context.toBits(FieldSize);
1755 setDataSize(std::max(getDataSizeInBits(), FieldSizeInBits));
1757 setDataSize(FieldOffset + FieldSize);
1760 setSize(std::max(getSizeInBits(), getDataSizeInBits()));
1762 // Remember max struct/class alignment.
1763 UpdateAlignment(FieldAlign, UnpackedFieldAlign);
1766 void RecordLayoutBuilder::FinishLayout(const NamedDecl *D) {
1767 // In C++, records cannot be of size 0.
1768 if (Context.getLangOpts().CPlusPlus && getSizeInBits() == 0) {
1769 if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D)) {
1770 // Compatibility with gcc requires a class (pod or non-pod)
1771 // which is not empty but of size 0; such as having fields of
1772 // array of zero-length, remains of Size 0
1774 setSize(CharUnits::One());
1777 setSize(CharUnits::One());
1780 // Finally, round the size of the record up to the alignment of the
1782 uint64_t UnpaddedSize = getSizeInBits() - UnfilledBitsInLastUnit;
1783 uint64_t UnpackedSizeInBits =
1784 llvm::RoundUpToAlignment(getSizeInBits(),
1785 Context.toBits(UnpackedAlignment));
1786 CharUnits UnpackedSize = Context.toCharUnitsFromBits(UnpackedSizeInBits);
1787 uint64_t RoundedSize
1788 = llvm::RoundUpToAlignment(getSizeInBits(), Context.toBits(Alignment));
1790 if (ExternalLayout) {
1791 // If we're inferring alignment, and the external size is smaller than
1792 // our size after we've rounded up to alignment, conservatively set the
1794 if (InferAlignment && ExternalSize < RoundedSize) {
1795 Alignment = CharUnits::One();
1796 InferAlignment = false;
1798 setSize(ExternalSize);
1802 // Set the size to the final size.
1803 setSize(RoundedSize);
1805 unsigned CharBitNum = Context.getTargetInfo().getCharWidth();
1806 if (const RecordDecl *RD = dyn_cast<RecordDecl>(D)) {
1807 // Warn if padding was introduced to the struct/class/union.
1808 if (getSizeInBits() > UnpaddedSize) {
1809 unsigned PadSize = getSizeInBits() - UnpaddedSize;
1811 if (PadSize % CharBitNum == 0) {
1812 PadSize = PadSize / CharBitNum;
1815 Diag(RD->getLocation(), diag::warn_padded_struct_size)
1816 << Context.getTypeDeclType(RD)
1818 << (InBits ? 1 : 0) /*(byte|bit)*/ << (PadSize > 1); // plural or not
1821 // Warn if we packed it unnecessarily. If the alignment is 1 byte don't
1822 // bother since there won't be alignment issues.
1823 if (Packed && UnpackedAlignment > CharUnits::One() &&
1824 getSize() == UnpackedSize)
1825 Diag(D->getLocation(), diag::warn_unnecessary_packed)
1826 << Context.getTypeDeclType(RD);
1830 void RecordLayoutBuilder::UpdateAlignment(CharUnits NewAlignment,
1831 CharUnits UnpackedNewAlignment) {
1832 // The alignment is not modified when using 'mac68k' alignment or when
1833 // we have an externally-supplied layout that also provides overall alignment.
1834 if (IsMac68kAlign || (ExternalLayout && !InferAlignment))
1837 if (NewAlignment > Alignment) {
1838 assert(llvm::isPowerOf2_32(NewAlignment.getQuantity() &&
1839 "Alignment not a power of 2"));
1840 Alignment = NewAlignment;
1843 if (UnpackedNewAlignment > UnpackedAlignment) {
1844 assert(llvm::isPowerOf2_32(UnpackedNewAlignment.getQuantity() &&
1845 "Alignment not a power of 2"));
1846 UnpackedAlignment = UnpackedNewAlignment;
1851 RecordLayoutBuilder::updateExternalFieldOffset(const FieldDecl *Field,
1852 uint64_t ComputedOffset) {
1853 assert(ExternalFieldOffsets.find(Field) != ExternalFieldOffsets.end() &&
1854 "Field does not have an external offset");
1856 uint64_t ExternalFieldOffset = ExternalFieldOffsets[Field];
1858 if (InferAlignment && ExternalFieldOffset < ComputedOffset) {
1859 // The externally-supplied field offset is before the field offset we
1860 // computed. Assume that the structure is packed.
1861 Alignment = CharUnits::One();
1862 InferAlignment = false;
1865 // Use the externally-supplied field offset.
1866 return ExternalFieldOffset;
1869 /// \brief Get diagnostic %select index for tag kind for
1870 /// field padding diagnostic message.
1871 /// WARNING: Indexes apply to particular diagnostics only!
1873 /// \returns diagnostic %select index.
1874 static unsigned getPaddingDiagFromTagKind(TagTypeKind Tag) {
1876 case TTK_Struct: return 0;
1877 case TTK_Interface: return 1;
1878 case TTK_Class: return 2;
1879 default: llvm_unreachable("Invalid tag kind for field padding diagnostic!");
1883 void RecordLayoutBuilder::CheckFieldPadding(uint64_t Offset,
1884 uint64_t UnpaddedOffset,
1885 uint64_t UnpackedOffset,
1886 unsigned UnpackedAlign,
1888 const FieldDecl *D) {
1889 // We let objc ivars without warning, objc interfaces generally are not used
1890 // for padding tricks.
1891 if (isa<ObjCIvarDecl>(D))
1894 // Don't warn about structs created without a SourceLocation. This can
1895 // be done by clients of the AST, such as codegen.
1896 if (D->getLocation().isInvalid())
1899 unsigned CharBitNum = Context.getTargetInfo().getCharWidth();
1901 // Warn if padding was introduced to the struct/class.
1902 if (!IsUnion && Offset > UnpaddedOffset) {
1903 unsigned PadSize = Offset - UnpaddedOffset;
1905 if (PadSize % CharBitNum == 0) {
1906 PadSize = PadSize / CharBitNum;
1909 if (D->getIdentifier())
1910 Diag(D->getLocation(), diag::warn_padded_struct_field)
1911 << getPaddingDiagFromTagKind(D->getParent()->getTagKind())
1912 << Context.getTypeDeclType(D->getParent())
1914 << (InBits ? 1 : 0) /*(byte|bit)*/ << (PadSize > 1) // plural or not
1915 << D->getIdentifier();
1917 Diag(D->getLocation(), diag::warn_padded_struct_anon_field)
1918 << getPaddingDiagFromTagKind(D->getParent()->getTagKind())
1919 << Context.getTypeDeclType(D->getParent())
1921 << (InBits ? 1 : 0) /*(byte|bit)*/ << (PadSize > 1); // plural or not
1924 // Warn if we packed it unnecessarily. If the alignment is 1 byte don't
1925 // bother since there won't be alignment issues.
1926 if (isPacked && UnpackedAlign > CharBitNum && Offset == UnpackedOffset)
1927 Diag(D->getLocation(), diag::warn_unnecessary_packed)
1928 << D->getIdentifier();
1931 static const CXXMethodDecl *computeKeyFunction(ASTContext &Context,
1932 const CXXRecordDecl *RD) {
1933 // If a class isn't polymorphic it doesn't have a key function.
1934 if (!RD->isPolymorphic())
1937 // A class that is not externally visible doesn't have a key function. (Or
1938 // at least, there's no point to assigning a key function to such a class;
1939 // this doesn't affect the ABI.)
1940 if (!RD->isExternallyVisible())
1943 // Template instantiations don't have key functions per Itanium C++ ABI 5.2.6.
1944 // Same behavior as GCC.
1945 TemplateSpecializationKind TSK = RD->getTemplateSpecializationKind();
1946 if (TSK == TSK_ImplicitInstantiation ||
1947 TSK == TSK_ExplicitInstantiationDeclaration ||
1948 TSK == TSK_ExplicitInstantiationDefinition)
1951 bool allowInlineFunctions =
1952 Context.getTargetInfo().getCXXABI().canKeyFunctionBeInline();
1954 for (const CXXMethodDecl *MD : RD->methods()) {
1955 if (!MD->isVirtual())
1961 // Ignore implicit member functions, they are always marked as inline, but
1962 // they don't have a body until they're defined.
1963 if (MD->isImplicit())
1966 if (MD->isInlineSpecified())
1969 if (MD->hasInlineBody())
1972 // Ignore inline deleted or defaulted functions.
1973 if (!MD->isUserProvided())
1976 // In certain ABIs, ignore functions with out-of-line inline definitions.
1977 if (!allowInlineFunctions) {
1978 const FunctionDecl *Def;
1979 if (MD->hasBody(Def) && Def->isInlineSpecified())
1991 RecordLayoutBuilder::Diag(SourceLocation Loc, unsigned DiagID) {
1992 return Context.getDiagnostics().Report(Loc, DiagID);
1995 /// Does the target C++ ABI require us to skip over the tail-padding
1996 /// of the given class (considering it as a base class) when allocating
1998 static bool mustSkipTailPadding(TargetCXXABI ABI, const CXXRecordDecl *RD) {
1999 switch (ABI.getTailPaddingUseRules()) {
2000 case TargetCXXABI::AlwaysUseTailPadding:
2003 case TargetCXXABI::UseTailPaddingUnlessPOD03:
2004 // FIXME: To the extent that this is meant to cover the Itanium ABI
2005 // rules, we should implement the restrictions about over-sized
2008 // http://mentorembedded.github.com/cxx-abi/abi.html#POD :
2009 // In general, a type is considered a POD for the purposes of
2010 // layout if it is a POD type (in the sense of ISO C++
2011 // [basic.types]). However, a POD-struct or POD-union (in the
2012 // sense of ISO C++ [class]) with a bitfield member whose
2013 // declared width is wider than the declared type of the
2014 // bitfield is not a POD for the purpose of layout. Similarly,
2015 // an array type is not a POD for the purpose of layout if the
2016 // element type of the array is not a POD for the purpose of
2019 // Where references to the ISO C++ are made in this paragraph,
2020 // the Technical Corrigendum 1 version of the standard is
2024 case TargetCXXABI::UseTailPaddingUnlessPOD11:
2025 // This is equivalent to RD->getTypeForDecl().isCXX11PODType(),
2026 // but with a lot of abstraction penalty stripped off. This does
2027 // assume that these properties are set correctly even in C++98
2028 // mode; fortunately, that is true because we want to assign
2029 // consistently semantics to the type-traits intrinsics (or at
2030 // least as many of them as possible).
2031 return RD->isTrivial() && RD->isStandardLayout();
2034 llvm_unreachable("bad tail-padding use kind");
2037 static bool isMsLayout(const RecordDecl* D) {
2038 return D->getASTContext().getTargetInfo().getCXXABI().isMicrosoft();
2041 // This section contains an implementation of struct layout that is, up to the
2042 // included tests, compatible with cl.exe (2013). The layout produced is
2043 // significantly different than those produced by the Itanium ABI. Here we note
2044 // the most important differences.
2046 // * The alignment of bitfields in unions is ignored when computing the
2047 // alignment of the union.
2048 // * The existence of zero-width bitfield that occurs after anything other than
2049 // a non-zero length bitfield is ignored.
2050 // * There is no explicit primary base for the purposes of layout. All bases
2051 // with vfptrs are laid out first, followed by all bases without vfptrs.
2052 // * The Itanium equivalent vtable pointers are split into a vfptr (virtual
2053 // function pointer) and a vbptr (virtual base pointer). They can each be
2054 // shared with a, non-virtual bases. These bases need not be the same. vfptrs
2055 // always occur at offset 0. vbptrs can occur at an arbitrary offset and are
2056 // placed after the lexiographically last non-virtual base. This placement
2057 // is always before fields but can be in the middle of the non-virtual bases
2058 // due to the two-pass layout scheme for non-virtual-bases.
2059 // * Virtual bases sometimes require a 'vtordisp' field that is laid out before
2060 // the virtual base and is used in conjunction with virtual overrides during
2061 // construction and destruction. This is always a 4 byte value and is used as
2062 // an alternative to constructor vtables.
2063 // * vtordisps are allocated in a block of memory with size and alignment equal
2064 // to the alignment of the completed structure (before applying __declspec(
2065 // align())). The vtordisp always occur at the end of the allocation block,
2066 // immediately prior to the virtual base.
2067 // * vfptrs are injected after all bases and fields have been laid out. In
2068 // order to guarantee proper alignment of all fields, the vfptr injection
2069 // pushes all bases and fields back by the alignment imposed by those bases
2070 // and fields. This can potentially add a significant amount of padding.
2071 // vfptrs are always injected at offset 0.
2072 // * vbptrs are injected after all bases and fields have been laid out. In
2073 // order to guarantee proper alignment of all fields, the vfptr injection
2074 // pushes all bases and fields back by the alignment imposed by those bases
2075 // and fields. This can potentially add a significant amount of padding.
2076 // vbptrs are injected immediately after the last non-virtual base as
2077 // lexiographically ordered in the code. If this site isn't pointer aligned
2078 // the vbptr is placed at the next properly aligned location. Enough padding
2079 // is added to guarantee a fit.
2080 // * The last zero sized non-virtual base can be placed at the end of the
2081 // struct (potentially aliasing another object), or may alias with the first
2082 // field, even if they are of the same type.
2083 // * The last zero size virtual base may be placed at the end of the struct
2084 // potentially aliasing another object.
2085 // * The ABI attempts to avoid aliasing of zero sized bases by adding padding
2086 // between bases or vbases with specific properties. The criteria for
2087 // additional padding between two bases is that the first base is zero sized
2088 // or ends with a zero sized subobject and the second base is zero sized or
2089 // trails with a zero sized base or field (sharing of vfptrs can reorder the
2090 // layout of the so the leading base is not always the first one declared).
2091 // This rule does take into account fields that are not records, so padding
2092 // will occur even if the last field is, e.g. an int. The padding added for
2093 // bases is 1 byte. The padding added between vbases depends on the alignment
2094 // of the object but is at least 4 bytes (in both 32 and 64 bit modes).
2095 // * There is no concept of non-virtual alignment, non-virtual alignment and
2096 // alignment are always identical.
2097 // * There is a distinction between alignment and required alignment.
2098 // __declspec(align) changes the required alignment of a struct. This
2099 // alignment is _always_ obeyed, even in the presence of #pragma pack. A
2100 // record inherites required alignment from all of its fields an bases.
2101 // * __declspec(align) on bitfields has the effect of changing the bitfield's
2102 // alignment instead of its required alignment. This is the only known way
2103 // to make the alignment of a struct bigger than 8. Interestingly enough
2104 // this alignment is also immune to the effects of #pragma pack and can be
2105 // used to create structures with large alignment under #pragma pack.
2106 // However, because it does not impact required alignment, such a structure,
2107 // when used as a field or base, will not be aligned if #pragma pack is
2108 // still active at the time of use.
2110 // Known incompatibilities:
2111 // * all: #pragma pack between fields in a record
2112 // * 2010 and back: If the last field in a record is a bitfield, every object
2113 // laid out after the record will have extra padding inserted before it. The
2114 // extra padding will have size equal to the size of the storage class of the
2115 // bitfield. 0 sized bitfields don't exhibit this behavior and the extra
2116 // padding can be avoided by adding a 0 sized bitfield after the non-zero-
2118 // * 2012 and back: In 64-bit mode, if the alignment of a record is 16 or
2119 // greater due to __declspec(align()) then a second layout phase occurs after
2120 // The locations of the vf and vb pointers are known. This layout phase
2121 // suffers from the "last field is a bitfield" bug in 2010 and results in
2122 // _every_ field getting padding put in front of it, potentially including the
2123 // vfptr, leaving the vfprt at a non-zero location which results in a fault if
2124 // anything tries to read the vftbl. The second layout phase also treats
2125 // bitfields as separate entities and gives them each storage rather than
2126 // packing them. Additionally, because this phase appears to perform a
2127 // (an unstable) sort on the members before laying them out and because merged
2128 // bitfields have the same address, the bitfields end up in whatever order
2129 // the sort left them in, a behavior we could never hope to replicate.
2132 struct MicrosoftRecordLayoutBuilder {
2133 struct ElementInfo {
2135 CharUnits Alignment;
2137 typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsetsMapTy;
2138 MicrosoftRecordLayoutBuilder(const ASTContext &Context) : Context(Context) {}
2140 MicrosoftRecordLayoutBuilder(const MicrosoftRecordLayoutBuilder &)
2141 LLVM_DELETED_FUNCTION;
2142 void operator=(const MicrosoftRecordLayoutBuilder &) LLVM_DELETED_FUNCTION;
2144 void layout(const RecordDecl *RD);
2145 void cxxLayout(const CXXRecordDecl *RD);
2146 /// \brief Initializes size and alignment and honors some flags.
2147 void initializeLayout(const RecordDecl *RD);
2148 /// \brief Initialized C++ layout, compute alignment and virtual alignment and
2149 /// existence of vfptrs and vbptrs. Alignment is needed before the vfptr is
2151 void initializeCXXLayout(const CXXRecordDecl *RD);
2152 void layoutNonVirtualBases(const CXXRecordDecl *RD);
2153 void layoutNonVirtualBase(const CXXRecordDecl *BaseDecl,
2154 const ASTRecordLayout &BaseLayout,
2155 const ASTRecordLayout *&PreviousBaseLayout);
2156 void injectVFPtr(const CXXRecordDecl *RD);
2157 void injectVBPtr(const CXXRecordDecl *RD);
2158 /// \brief Lays out the fields of the record. Also rounds size up to
2160 void layoutFields(const RecordDecl *RD);
2161 void layoutField(const FieldDecl *FD);
2162 void layoutBitField(const FieldDecl *FD);
2163 /// \brief Lays out a single zero-width bit-field in the record and handles
2164 /// special cases associated with zero-width bit-fields.
2165 void layoutZeroWidthBitField(const FieldDecl *FD);
2166 void layoutVirtualBases(const CXXRecordDecl *RD);
2167 void finalizeLayout(const RecordDecl *RD);
2168 /// \brief Gets the size and alignment of a base taking pragma pack and
2169 /// __declspec(align) into account.
2170 ElementInfo getAdjustedElementInfo(const ASTRecordLayout &Layout);
2171 /// \brief Gets the size and alignment of a field taking pragma pack and
2172 /// __declspec(align) into account. It also updates RequiredAlignment as a
2173 /// side effect because it is most convenient to do so here.
2174 ElementInfo getAdjustedElementInfo(const FieldDecl *FD);
2175 /// \brief Places a field at an offset in CharUnits.
2176 void placeFieldAtOffset(CharUnits FieldOffset) {
2177 FieldOffsets.push_back(Context.toBits(FieldOffset));
2179 /// \brief Places a bitfield at a bit offset.
2180 void placeFieldAtBitOffset(uint64_t FieldOffset) {
2181 FieldOffsets.push_back(FieldOffset);
2183 /// \brief Compute the set of virtual bases for which vtordisps are required.
2184 llvm::SmallPtrSet<const CXXRecordDecl *, 2>
2185 computeVtorDispSet(const CXXRecordDecl *RD);
2186 const ASTContext &Context;
2187 /// \brief The size of the record being laid out.
2189 /// \brief The non-virtual size of the record layout.
2190 CharUnits NonVirtualSize;
2191 /// \brief The data size of the record layout.
2193 /// \brief The current alignment of the record layout.
2194 CharUnits Alignment;
2195 /// \brief The maximum allowed field alignment. This is set by #pragma pack.
2196 CharUnits MaxFieldAlignment;
2197 /// \brief The alignment that this record must obey. This is imposed by
2198 /// __declspec(align()) on the record itself or one of its fields or bases.
2199 CharUnits RequiredAlignment;
2200 /// \brief The size of the allocation of the currently active bitfield.
2201 /// This value isn't meaningful unless LastFieldIsNonZeroWidthBitfield
2203 CharUnits CurrentBitfieldSize;
2204 /// \brief Offset to the virtual base table pointer (if one exists).
2205 CharUnits VBPtrOffset;
2206 /// \brief The size and alignment info of a pointer.
2207 ElementInfo PointerInfo;
2208 /// \brief The primary base class (if one exists).
2209 const CXXRecordDecl *PrimaryBase;
2210 /// \brief The class we share our vb-pointer with.
2211 const CXXRecordDecl *SharedVBPtrBase;
2212 /// \brief The collection of field offsets.
2213 SmallVector<uint64_t, 16> FieldOffsets;
2214 /// \brief Base classes and their offsets in the record.
2215 BaseOffsetsMapTy Bases;
2216 /// \brief virtual base classes and their offsets in the record.
2217 ASTRecordLayout::VBaseOffsetsMapTy VBases;
2218 /// \brief The number of remaining bits in our last bitfield allocation.
2219 /// This value isn't meaningful unless LastFieldIsNonZeroWidthBitfield is
2221 unsigned RemainingBitsInField;
2223 /// \brief True if the last field laid out was a bitfield and was not 0
2225 bool LastFieldIsNonZeroWidthBitfield : 1;
2226 /// \brief True if the class has its own vftable pointer.
2227 bool HasOwnVFPtr : 1;
2228 /// \brief True if the class has a vbtable pointer.
2230 /// \brief True if the last sub-object within the type is zero sized or the
2231 /// object itself is zero sized. This *does not* count members that are not
2232 /// records. Only used for MS-ABI.
2233 bool EndsWithZeroSizedObject : 1;
2234 /// \brief True if this class is zero sized or first base is zero sized or
2235 /// has this property. Only used for MS-ABI.
2236 bool LeadsWithZeroSizedBase : 1;
2240 MicrosoftRecordLayoutBuilder::ElementInfo
2241 MicrosoftRecordLayoutBuilder::getAdjustedElementInfo(
2242 const ASTRecordLayout &Layout) {
2244 Info.Alignment = Layout.getAlignment();
2245 // Respect pragma pack.
2246 if (!MaxFieldAlignment.isZero())
2247 Info.Alignment = std::min(Info.Alignment, MaxFieldAlignment);
2248 // Track zero-sized subobjects here where it's already available.
2249 EndsWithZeroSizedObject = Layout.hasZeroSizedSubObject();
2250 // Respect required alignment, this is necessary because we may have adjusted
2251 // the alignment in the case of pragam pack. Note that the required alignment
2252 // doesn't actually apply to the struct alignment at this point.
2253 Alignment = std::max(Alignment, Info.Alignment);
2254 RequiredAlignment = std::max(RequiredAlignment, Layout.getRequiredAlignment());
2255 Info.Alignment = std::max(Info.Alignment, Layout.getRequiredAlignment());
2256 Info.Size = Layout.getNonVirtualSize();
2260 MicrosoftRecordLayoutBuilder::ElementInfo
2261 MicrosoftRecordLayoutBuilder::getAdjustedElementInfo(
2262 const FieldDecl *FD) {
2264 std::tie(Info.Size, Info.Alignment) =
2265 Context.getTypeInfoInChars(FD->getType());
2266 // Respect align attributes.
2267 CharUnits FieldRequiredAlignment =
2268 Context.toCharUnitsFromBits(FD->getMaxAlignment());
2269 // Respect attributes applied to subobjects of the field.
2270 if (FD->isBitField())
2271 // For some reason __declspec align impacts alignment rather than required
2272 // alignment when it is applied to bitfields.
2273 Info.Alignment = std::max(Info.Alignment, FieldRequiredAlignment);
2276 FD->getType()->getBaseElementTypeUnsafe()->getAs<RecordType>()) {
2277 auto const &Layout = Context.getASTRecordLayout(RT->getDecl());
2278 EndsWithZeroSizedObject = Layout.hasZeroSizedSubObject();
2279 FieldRequiredAlignment = std::max(FieldRequiredAlignment,
2280 Layout.getRequiredAlignment());
2282 // Capture required alignment as a side-effect.
2283 RequiredAlignment = std::max(RequiredAlignment, FieldRequiredAlignment);
2285 // Respect pragma pack, attribute pack and declspec align
2286 if (!MaxFieldAlignment.isZero())
2287 Info.Alignment = std::min(Info.Alignment, MaxFieldAlignment);
2288 if (FD->hasAttr<PackedAttr>())
2289 Info.Alignment = CharUnits::One();
2290 Info.Alignment = std::max(Info.Alignment, FieldRequiredAlignment);
2294 void MicrosoftRecordLayoutBuilder::layout(const RecordDecl *RD) {
2295 initializeLayout(RD);
2297 DataSize = Size = Size.RoundUpToAlignment(Alignment);
2298 RequiredAlignment = std::max(
2299 RequiredAlignment, Context.toCharUnitsFromBits(RD->getMaxAlignment()));
2303 void MicrosoftRecordLayoutBuilder::cxxLayout(const CXXRecordDecl *RD) {
2304 initializeLayout(RD);
2305 initializeCXXLayout(RD);
2306 layoutNonVirtualBases(RD);
2310 if (HasOwnVFPtr || (HasVBPtr && !SharedVBPtrBase))
2311 Alignment = std::max(Alignment, PointerInfo.Alignment);
2312 auto RoundingAlignment = Alignment;
2313 if (!MaxFieldAlignment.isZero())
2314 RoundingAlignment = std::min(RoundingAlignment, MaxFieldAlignment);
2315 NonVirtualSize = Size = Size.RoundUpToAlignment(RoundingAlignment);
2316 RequiredAlignment = std::max(
2317 RequiredAlignment, Context.toCharUnitsFromBits(RD->getMaxAlignment()));
2318 layoutVirtualBases(RD);
2322 void MicrosoftRecordLayoutBuilder::initializeLayout(const RecordDecl *RD) {
2323 IsUnion = RD->isUnion();
2324 Size = CharUnits::Zero();
2325 Alignment = CharUnits::One();
2326 // In 64-bit mode we always perform an alignment step after laying out vbases.
2327 // In 32-bit mode we do not. The check to see if we need to perform alignment
2328 // checks the RequiredAlignment field and performs alignment if it isn't 0.
2329 RequiredAlignment = Context.getTargetInfo().getPointerWidth(0) == 64 ?
2330 CharUnits::One() : CharUnits::Zero();
2331 // Compute the maximum field alignment.
2332 MaxFieldAlignment = CharUnits::Zero();
2333 // Honor the default struct packing maximum alignment flag.
2334 if (unsigned DefaultMaxFieldAlignment = Context.getLangOpts().PackStruct)
2335 MaxFieldAlignment = CharUnits::fromQuantity(DefaultMaxFieldAlignment);
2336 // Honor the packing attribute. The MS-ABI ignores pragma pack if its larger
2337 // than the pointer size.
2338 if (const MaxFieldAlignmentAttr *MFAA = RD->getAttr<MaxFieldAlignmentAttr>()){
2339 unsigned PackedAlignment = MFAA->getAlignment();
2340 if (PackedAlignment <= Context.getTargetInfo().getPointerWidth(0))
2341 MaxFieldAlignment = Context.toCharUnitsFromBits(PackedAlignment);
2343 // Packed attribute forces max field alignment to be 1.
2344 if (RD->hasAttr<PackedAttr>())
2345 MaxFieldAlignment = CharUnits::One();
2349 MicrosoftRecordLayoutBuilder::initializeCXXLayout(const CXXRecordDecl *RD) {
2350 EndsWithZeroSizedObject = false;
2351 LeadsWithZeroSizedBase = false;
2352 HasOwnVFPtr = false;
2354 PrimaryBase = nullptr;
2355 SharedVBPtrBase = nullptr;
2356 // Calculate pointer size and alignment. These are used for vfptr and vbprt
2359 Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
2360 PointerInfo.Alignment = PointerInfo.Size;
2361 // Respect pragma pack.
2362 if (!MaxFieldAlignment.isZero())
2363 PointerInfo.Alignment = std::min(PointerInfo.Alignment, MaxFieldAlignment);
2367 MicrosoftRecordLayoutBuilder::layoutNonVirtualBases(const CXXRecordDecl *RD) {
2368 // The MS-ABI lays out all bases that contain leading vfptrs before it lays
2369 // out any bases that do not contain vfptrs. We implement this as two passes
2370 // over the bases. This approach guarantees that the primary base is laid out
2371 // first. We use these passes to calculate some additional aggregated
2372 // information about the bases, such as reqruied alignment and the presence of
2373 // zero sized members.
2374 const ASTRecordLayout *PreviousBaseLayout = nullptr;
2375 // Iterate through the bases and lay out the non-virtual ones.
2376 for (const CXXBaseSpecifier &Base : RD->bases()) {
2377 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2378 const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2379 // Mark and skip virtual bases.
2380 if (Base.isVirtual()) {
2384 // Check fo a base to share a VBPtr with.
2385 if (!SharedVBPtrBase && BaseLayout.hasVBPtr()) {
2386 SharedVBPtrBase = BaseDecl;
2389 // Only lay out bases with extendable VFPtrs on the first pass.
2390 if (!BaseLayout.hasExtendableVFPtr())
2392 // If we don't have a primary base, this one qualifies.
2394 PrimaryBase = BaseDecl;
2395 LeadsWithZeroSizedBase = BaseLayout.leadsWithZeroSizedBase();
2397 // Lay out the base.
2398 layoutNonVirtualBase(BaseDecl, BaseLayout, PreviousBaseLayout);
2400 // Figure out if we need a fresh VFPtr for this class.
2401 if (!PrimaryBase && RD->isDynamicClass())
2402 for (CXXRecordDecl::method_iterator i = RD->method_begin(),
2403 e = RD->method_end();
2404 !HasOwnVFPtr && i != e; ++i)
2405 HasOwnVFPtr = i->isVirtual() && i->size_overridden_methods() == 0;
2406 // If we don't have a primary base then we have a leading object that could
2407 // itself lead with a zero-sized object, something we track.
2408 bool CheckLeadingLayout = !PrimaryBase;
2409 // Iterate through the bases and lay out the non-virtual ones.
2410 for (const CXXBaseSpecifier &Base : RD->bases()) {
2411 if (Base.isVirtual())
2413 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2414 const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2415 // Only lay out bases without extendable VFPtrs on the second pass.
2416 if (BaseLayout.hasExtendableVFPtr()) {
2417 VBPtrOffset = Bases[BaseDecl] + BaseLayout.getNonVirtualSize();
2420 // If this is the first layout, check to see if it leads with a zero sized
2421 // object. If it does, so do we.
2422 if (CheckLeadingLayout) {
2423 CheckLeadingLayout = false;
2424 LeadsWithZeroSizedBase = BaseLayout.leadsWithZeroSizedBase();
2426 // Lay out the base.
2427 layoutNonVirtualBase(BaseDecl, BaseLayout, PreviousBaseLayout);
2428 VBPtrOffset = Bases[BaseDecl] + BaseLayout.getNonVirtualSize();
2430 // Set our VBPtroffset if we know it at this point.
2432 VBPtrOffset = CharUnits::fromQuantity(-1);
2433 else if (SharedVBPtrBase) {
2434 const ASTRecordLayout &Layout = Context.getASTRecordLayout(SharedVBPtrBase);
2435 VBPtrOffset = Bases[SharedVBPtrBase] + Layout.getVBPtrOffset();
2439 void MicrosoftRecordLayoutBuilder::layoutNonVirtualBase(
2440 const CXXRecordDecl *BaseDecl,
2441 const ASTRecordLayout &BaseLayout,
2442 const ASTRecordLayout *&PreviousBaseLayout) {
2443 // Insert padding between two bases if the left first one is zero sized or
2444 // contains a zero sized subobject and the right is zero sized or one leads
2445 // with a zero sized base.
2446 if (PreviousBaseLayout && PreviousBaseLayout->hasZeroSizedSubObject() &&
2447 BaseLayout.leadsWithZeroSizedBase())
2449 ElementInfo Info = getAdjustedElementInfo(BaseLayout);
2450 CharUnits BaseOffset = Size.RoundUpToAlignment(Info.Alignment);
2451 Bases.insert(std::make_pair(BaseDecl, BaseOffset));
2452 Size = BaseOffset + BaseLayout.getNonVirtualSize();
2453 PreviousBaseLayout = &BaseLayout;
2456 void MicrosoftRecordLayoutBuilder::layoutFields(const RecordDecl *RD) {
2457 LastFieldIsNonZeroWidthBitfield = false;
2458 for (const FieldDecl *Field : RD->fields())
2462 void MicrosoftRecordLayoutBuilder::layoutField(const FieldDecl *FD) {
2463 if (FD->isBitField()) {
2467 LastFieldIsNonZeroWidthBitfield = false;
2468 ElementInfo Info = getAdjustedElementInfo(FD);
2469 Alignment = std::max(Alignment, Info.Alignment);
2471 placeFieldAtOffset(CharUnits::Zero());
2472 Size = std::max(Size, Info.Size);
2474 CharUnits FieldOffset = Size.RoundUpToAlignment(Info.Alignment);
2475 placeFieldAtOffset(FieldOffset);
2476 Size = FieldOffset + Info.Size;
2480 void MicrosoftRecordLayoutBuilder::layoutBitField(const FieldDecl *FD) {
2481 unsigned Width = FD->getBitWidthValue(Context);
2483 layoutZeroWidthBitField(FD);
2486 ElementInfo Info = getAdjustedElementInfo(FD);
2487 // Clamp the bitfield to a containable size for the sake of being able
2488 // to lay them out. Sema will throw an error.
2489 if (Width > Context.toBits(Info.Size))
2490 Width = Context.toBits(Info.Size);
2491 // Check to see if this bitfield fits into an existing allocation. Note:
2492 // MSVC refuses to pack bitfields of formal types with different sizes
2493 // into the same allocation.
2494 if (!IsUnion && LastFieldIsNonZeroWidthBitfield &&
2495 CurrentBitfieldSize == Info.Size && Width <= RemainingBitsInField) {
2496 placeFieldAtBitOffset(Context.toBits(Size) - RemainingBitsInField);
2497 RemainingBitsInField -= Width;
2500 LastFieldIsNonZeroWidthBitfield = true;
2501 CurrentBitfieldSize = Info.Size;
2503 placeFieldAtOffset(CharUnits::Zero());
2504 Size = std::max(Size, Info.Size);
2505 // TODO: Add a Sema warning that MS ignores bitfield alignment in unions.
2507 // Allocate a new block of memory and place the bitfield in it.
2508 CharUnits FieldOffset = Size.RoundUpToAlignment(Info.Alignment);
2509 placeFieldAtOffset(FieldOffset);
2510 Size = FieldOffset + Info.Size;
2511 Alignment = std::max(Alignment, Info.Alignment);
2512 RemainingBitsInField = Context.toBits(Info.Size) - Width;
2517 MicrosoftRecordLayoutBuilder::layoutZeroWidthBitField(const FieldDecl *FD) {
2518 // Zero-width bitfields are ignored unless they follow a non-zero-width
2520 if (!LastFieldIsNonZeroWidthBitfield) {
2521 placeFieldAtOffset(IsUnion ? CharUnits::Zero() : Size);
2522 // TODO: Add a Sema warning that MS ignores alignment for zero
2523 // sized bitfields that occur after zero-size bitfields or non-bitfields.
2526 LastFieldIsNonZeroWidthBitfield = false;
2527 ElementInfo Info = getAdjustedElementInfo(FD);
2529 placeFieldAtOffset(CharUnits::Zero());
2530 Size = std::max(Size, Info.Size);
2531 // TODO: Add a Sema warning that MS ignores bitfield alignment in unions.
2533 // Round up the current record size to the field's alignment boundary.
2534 CharUnits FieldOffset = Size.RoundUpToAlignment(Info.Alignment);
2535 placeFieldAtOffset(FieldOffset);
2537 Alignment = std::max(Alignment, Info.Alignment);
2541 void MicrosoftRecordLayoutBuilder::injectVBPtr(const CXXRecordDecl *RD) {
2542 if (!HasVBPtr || SharedVBPtrBase)
2544 // Inject the VBPointer at the injection site.
2545 CharUnits InjectionSite = VBPtrOffset;
2546 // But before we do, make sure it's properly aligned.
2547 VBPtrOffset = VBPtrOffset.RoundUpToAlignment(PointerInfo.Alignment);
2548 // Determine where the first field should be laid out after the vbptr.
2549 CharUnits FieldStart = VBPtrOffset + PointerInfo.Size;
2550 // Make sure that the amount we push the fields back by is a multiple of the
2552 CharUnits Offset = (FieldStart - InjectionSite).RoundUpToAlignment(
2553 std::max(RequiredAlignment, Alignment));
2554 // Increase the size of the object and push back all fields by the offset
2557 for (uint64_t &FieldOffset : FieldOffsets)
2558 FieldOffset += Context.toBits(Offset);
2559 for (BaseOffsetsMapTy::value_type &Base : Bases)
2560 if (Base.second >= InjectionSite)
2561 Base.second += Offset;
2564 void MicrosoftRecordLayoutBuilder::injectVFPtr(const CXXRecordDecl *RD) {
2567 // Make sure that the amount we push the struct back by is a multiple of the
2569 CharUnits Offset = PointerInfo.Size.RoundUpToAlignment(
2570 std::max(RequiredAlignment, Alignment));
2571 // Increase the size of the object and push back all fields, the vbptr and all
2572 // bases by the offset amount.
2574 for (uint64_t &FieldOffset : FieldOffsets)
2575 FieldOffset += Context.toBits(Offset);
2577 VBPtrOffset += Offset;
2578 for (BaseOffsetsMapTy::value_type &Base : Bases)
2579 Base.second += Offset;
2582 void MicrosoftRecordLayoutBuilder::layoutVirtualBases(const CXXRecordDecl *RD) {
2585 // Vtordisps are always 4 bytes (even in 64-bit mode)
2586 CharUnits VtorDispSize = CharUnits::fromQuantity(4);
2587 CharUnits VtorDispAlignment = VtorDispSize;
2588 // vtordisps respect pragma pack.
2589 if (!MaxFieldAlignment.isZero())
2590 VtorDispAlignment = std::min(VtorDispAlignment, MaxFieldAlignment);
2591 // The alignment of the vtordisp is at least the required alignment of the
2592 // entire record. This requirement may be present to support vtordisp
2594 for (const CXXBaseSpecifier &VBase : RD->vbases()) {
2595 const CXXRecordDecl *BaseDecl = VBase.getType()->getAsCXXRecordDecl();
2596 const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2598 std::max(RequiredAlignment, BaseLayout.getRequiredAlignment());
2600 VtorDispAlignment = std::max(VtorDispAlignment, RequiredAlignment);
2601 // Compute the vtordisp set.
2602 llvm::SmallPtrSet<const CXXRecordDecl *, 2> HasVtordispSet =
2603 computeVtorDispSet(RD);
2604 // Iterate through the virtual bases and lay them out.
2605 const ASTRecordLayout *PreviousBaseLayout = nullptr;
2606 for (const CXXBaseSpecifier &VBase : RD->vbases()) {
2607 const CXXRecordDecl *BaseDecl = VBase.getType()->getAsCXXRecordDecl();
2608 const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2609 bool HasVtordisp = HasVtordispSet.count(BaseDecl);
2610 // Insert padding between two bases if the left first one is zero sized or
2611 // contains a zero sized subobject and the right is zero sized or one leads
2612 // with a zero sized base. The padding between virtual bases is 4
2613 // bytes (in both 32 and 64 bits modes) and always involves rounding up to
2614 // the required alignment, we don't know why.
2615 if ((PreviousBaseLayout && PreviousBaseLayout->hasZeroSizedSubObject() &&
2616 BaseLayout.leadsWithZeroSizedBase()) || HasVtordisp) {
2617 Size = Size.RoundUpToAlignment(VtorDispAlignment) + VtorDispSize;
2618 Alignment = std::max(VtorDispAlignment, Alignment);
2620 // Insert the virtual base.
2621 ElementInfo Info = getAdjustedElementInfo(BaseLayout);
2622 CharUnits BaseOffset = Size.RoundUpToAlignment(Info.Alignment);
2623 VBases.insert(std::make_pair(BaseDecl,
2624 ASTRecordLayout::VBaseInfo(BaseOffset, HasVtordisp)));
2625 Size = BaseOffset + BaseLayout.getNonVirtualSize();
2626 PreviousBaseLayout = &BaseLayout;
2630 void MicrosoftRecordLayoutBuilder::finalizeLayout(const RecordDecl *RD) {
2631 // Respect required alignment. Note that in 32-bit mode Required alignment
2632 // may be 0 nad cause size not to be updated.
2634 if (!RequiredAlignment.isZero()) {
2635 Alignment = std::max(Alignment, RequiredAlignment);
2636 auto RoundingAlignment = Alignment;
2637 if (!MaxFieldAlignment.isZero())
2638 RoundingAlignment = std::min(RoundingAlignment, MaxFieldAlignment);
2639 RoundingAlignment = std::max(RoundingAlignment, RequiredAlignment);
2640 Size = Size.RoundUpToAlignment(RoundingAlignment);
2642 // Zero-sized structures have size equal to their alignment.
2643 if (Size.isZero()) {
2644 EndsWithZeroSizedObject = true;
2645 LeadsWithZeroSizedBase = true;
2650 // Recursively walks the non-virtual bases of a class and determines if any of
2651 // them are in the bases with overridden methods set.
2653 RequiresVtordisp(const llvm::SmallPtrSetImpl<const CXXRecordDecl *> &
2654 BasesWithOverriddenMethods,
2655 const CXXRecordDecl *RD) {
2656 if (BasesWithOverriddenMethods.count(RD))
2658 // If any of a virtual bases non-virtual bases (recursively) requires a
2659 // vtordisp than so does this virtual base.
2660 for (const CXXBaseSpecifier &Base : RD->bases())
2661 if (!Base.isVirtual() &&
2662 RequiresVtordisp(BasesWithOverriddenMethods,
2663 Base.getType()->getAsCXXRecordDecl()))
2668 llvm::SmallPtrSet<const CXXRecordDecl *, 2>
2669 MicrosoftRecordLayoutBuilder::computeVtorDispSet(const CXXRecordDecl *RD) {
2670 llvm::SmallPtrSet<const CXXRecordDecl *, 2> HasVtordispSet;
2672 // /vd2 or #pragma vtordisp(2): Always use vtordisps for virtual bases with
2674 if (RD->getMSVtorDispMode() == MSVtorDispAttr::ForVFTable) {
2675 for (const CXXBaseSpecifier &Base : RD->vbases()) {
2676 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2677 const ASTRecordLayout &Layout = Context.getASTRecordLayout(BaseDecl);
2678 if (Layout.hasExtendableVFPtr())
2679 HasVtordispSet.insert(BaseDecl);
2681 return HasVtordispSet;
2684 // If any of our bases need a vtordisp for this type, so do we. Check our
2685 // direct bases for vtordisp requirements.
2686 for (const CXXBaseSpecifier &Base : RD->bases()) {
2687 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2688 const ASTRecordLayout &Layout = Context.getASTRecordLayout(BaseDecl);
2689 for (const auto &bi : Layout.getVBaseOffsetsMap())
2690 if (bi.second.hasVtorDisp())
2691 HasVtordispSet.insert(bi.first);
2693 // We don't introduce any additional vtordisps if either:
2694 // * A user declared constructor or destructor aren't declared.
2695 // * #pragma vtordisp(0) or the /vd0 flag are in use.
2696 if ((!RD->hasUserDeclaredConstructor() && !RD->hasUserDeclaredDestructor()) ||
2697 RD->getMSVtorDispMode() == MSVtorDispAttr::Never)
2698 return HasVtordispSet;
2699 // /vd1 or #pragma vtordisp(1): Try to guess based on whether we think it's
2700 // possible for a partially constructed object with virtual base overrides to
2701 // escape a non-trivial constructor.
2702 assert(RD->getMSVtorDispMode() == MSVtorDispAttr::ForVBaseOverride);
2703 // Compute a set of base classes which define methods we override. A virtual
2704 // base in this set will require a vtordisp. A virtual base that transitively
2705 // contains one of these bases as a non-virtual base will also require a
2707 llvm::SmallPtrSet<const CXXMethodDecl *, 8> Work;
2708 llvm::SmallPtrSet<const CXXRecordDecl *, 2> BasesWithOverriddenMethods;
2709 // Seed the working set with our non-destructor virtual methods.
2710 for (const CXXMethodDecl *MD : RD->methods())
2711 if (MD->isVirtual() && !isa<CXXDestructorDecl>(MD))
2713 while (!Work.empty()) {
2714 const CXXMethodDecl *MD = *Work.begin();
2715 CXXMethodDecl::method_iterator i = MD->begin_overridden_methods(),
2716 e = MD->end_overridden_methods();
2717 // If a virtual method has no-overrides it lives in its parent's vtable.
2719 BasesWithOverriddenMethods.insert(MD->getParent());
2722 // We've finished processing this element, remove it from the working set.
2725 // For each of our virtual bases, check if it is in the set of overridden
2726 // bases or if it transitively contains a non-virtual base that is.
2727 for (const CXXBaseSpecifier &Base : RD->vbases()) {
2728 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2729 if (!HasVtordispSet.count(BaseDecl) &&
2730 RequiresVtordisp(BasesWithOverriddenMethods, BaseDecl))
2731 HasVtordispSet.insert(BaseDecl);
2733 return HasVtordispSet;
2736 /// \brief Get or compute information about the layout of the specified record
2737 /// (struct/union/class), which indicates its size and field position
2739 const ASTRecordLayout *
2740 ASTContext::BuildMicrosoftASTRecordLayout(const RecordDecl *D) const {
2741 MicrosoftRecordLayoutBuilder Builder(*this);
2742 if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D)) {
2743 Builder.cxxLayout(RD);
2744 return new (*this) ASTRecordLayout(
2745 *this, Builder.Size, Builder.Alignment, Builder.RequiredAlignment,
2746 Builder.HasOwnVFPtr,
2747 Builder.HasOwnVFPtr || Builder.PrimaryBase,
2748 Builder.VBPtrOffset, Builder.NonVirtualSize, Builder.FieldOffsets.data(),
2749 Builder.FieldOffsets.size(), Builder.NonVirtualSize,
2750 Builder.Alignment, CharUnits::Zero(), Builder.PrimaryBase,
2751 false, Builder.SharedVBPtrBase,
2752 Builder.EndsWithZeroSizedObject, Builder.LeadsWithZeroSizedBase,
2753 Builder.Bases, Builder.VBases);
2756 return new (*this) ASTRecordLayout(
2757 *this, Builder.Size, Builder.Alignment, Builder.RequiredAlignment,
2758 Builder.Size, Builder.FieldOffsets.data(), Builder.FieldOffsets.size());
2762 /// getASTRecordLayout - Get or compute information about the layout of the
2763 /// specified record (struct/union/class), which indicates its size and field
2764 /// position information.
2765 const ASTRecordLayout &
2766 ASTContext::getASTRecordLayout(const RecordDecl *D) const {
2767 // These asserts test different things. A record has a definition
2768 // as soon as we begin to parse the definition. That definition is
2769 // not a complete definition (which is what isDefinition() tests)
2770 // until we *finish* parsing the definition.
2772 if (D->hasExternalLexicalStorage() && !D->getDefinition())
2773 getExternalSource()->CompleteType(const_cast<RecordDecl*>(D));
2775 D = D->getDefinition();
2776 assert(D && "Cannot get layout of forward declarations!");
2777 assert(!D->isInvalidDecl() && "Cannot get layout of invalid decl!");
2778 assert(D->isCompleteDefinition() && "Cannot layout type before complete!");
2780 // Look up this layout, if already laid out, return what we have.
2781 // Note that we can't save a reference to the entry because this function
2783 const ASTRecordLayout *Entry = ASTRecordLayouts[D];
2784 if (Entry) return *Entry;
2786 const ASTRecordLayout *NewEntry = nullptr;
2788 if (isMsLayout(D) && !D->getASTContext().getExternalSource()) {
2789 NewEntry = BuildMicrosoftASTRecordLayout(D);
2790 } else if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D)) {
2791 EmptySubobjectMap EmptySubobjects(*this, RD);
2792 RecordLayoutBuilder Builder(*this, &EmptySubobjects);
2795 // In certain situations, we are allowed to lay out objects in the
2796 // tail-padding of base classes. This is ABI-dependent.
2797 // FIXME: this should be stored in the record layout.
2798 bool skipTailPadding =
2799 mustSkipTailPadding(getTargetInfo().getCXXABI(), cast<CXXRecordDecl>(D));
2801 // FIXME: This should be done in FinalizeLayout.
2802 CharUnits DataSize =
2803 skipTailPadding ? Builder.getSize() : Builder.getDataSize();
2804 CharUnits NonVirtualSize =
2805 skipTailPadding ? DataSize : Builder.NonVirtualSize;
2807 new (*this) ASTRecordLayout(*this, Builder.getSize(),
2809 /*RequiredAlignment : used by MS-ABI)*/
2811 Builder.HasOwnVFPtr,
2812 RD->isDynamicClass(),
2813 CharUnits::fromQuantity(-1),
2815 Builder.FieldOffsets.data(),
2816 Builder.FieldOffsets.size(),
2818 Builder.NonVirtualAlignment,
2819 EmptySubobjects.SizeOfLargestEmptySubobject,
2820 Builder.PrimaryBase,
2821 Builder.PrimaryBaseIsVirtual,
2822 nullptr, false, false,
2823 Builder.Bases, Builder.VBases);
2825 RecordLayoutBuilder Builder(*this, /*EmptySubobjects=*/nullptr);
2829 new (*this) ASTRecordLayout(*this, Builder.getSize(),
2831 /*RequiredAlignment : used by MS-ABI)*/
2834 Builder.FieldOffsets.data(),
2835 Builder.FieldOffsets.size());
2838 ASTRecordLayouts[D] = NewEntry;
2840 if (getLangOpts().DumpRecordLayouts) {
2841 llvm::outs() << "\n*** Dumping AST Record Layout\n";
2842 DumpRecordLayout(D, llvm::outs(), getLangOpts().DumpRecordLayoutsSimple);
2848 const CXXMethodDecl *ASTContext::getCurrentKeyFunction(const CXXRecordDecl *RD) {
2849 if (!getTargetInfo().getCXXABI().hasKeyFunctions())
2852 assert(RD->getDefinition() && "Cannot get key function for forward decl!");
2853 RD = cast<CXXRecordDecl>(RD->getDefinition());
2856 // 1) computing the key function might trigger deserialization, which might
2857 // invalidate iterators into KeyFunctions
2858 // 2) 'get' on the LazyDeclPtr might also trigger deserialization and
2859 // invalidate the LazyDeclPtr within the map itself
2860 LazyDeclPtr Entry = KeyFunctions[RD];
2861 const Decl *Result =
2862 Entry ? Entry.get(getExternalSource()) : computeKeyFunction(*this, RD);
2864 // Store it back if it changed.
2865 if (Entry.isOffset() || Entry.isValid() != bool(Result))
2866 KeyFunctions[RD] = const_cast<Decl*>(Result);
2868 return cast_or_null<CXXMethodDecl>(Result);
2871 void ASTContext::setNonKeyFunction(const CXXMethodDecl *Method) {
2872 assert(Method == Method->getFirstDecl() &&
2873 "not working with method declaration from class definition");
2875 // Look up the cache entry. Since we're working with the first
2876 // declaration, its parent must be the class definition, which is
2877 // the correct key for the KeyFunctions hash.
2878 llvm::DenseMap<const CXXRecordDecl*, LazyDeclPtr>::iterator
2879 I = KeyFunctions.find(Method->getParent());
2881 // If it's not cached, there's nothing to do.
2882 if (I == KeyFunctions.end()) return;
2884 // If it is cached, check whether it's the target method, and if so,
2885 // remove it from the cache. Note, the call to 'get' might invalidate
2886 // the iterator and the LazyDeclPtr object within the map.
2887 LazyDeclPtr Ptr = I->second;
2888 if (Ptr.get(getExternalSource()) == Method) {
2889 // FIXME: remember that we did this for module / chained PCH state?
2890 KeyFunctions.erase(Method->getParent());
2894 static uint64_t getFieldOffset(const ASTContext &C, const FieldDecl *FD) {
2895 const ASTRecordLayout &Layout = C.getASTRecordLayout(FD->getParent());
2896 return Layout.getFieldOffset(FD->getFieldIndex());
2899 uint64_t ASTContext::getFieldOffset(const ValueDecl *VD) const {
2900 uint64_t OffsetInBits;
2901 if (const FieldDecl *FD = dyn_cast<FieldDecl>(VD)) {
2902 OffsetInBits = ::getFieldOffset(*this, FD);
2904 const IndirectFieldDecl *IFD = cast<IndirectFieldDecl>(VD);
2907 for (const NamedDecl *ND : IFD->chain())
2908 OffsetInBits += ::getFieldOffset(*this, cast<FieldDecl>(ND));
2911 return OffsetInBits;
2914 /// getObjCLayout - Get or compute information about the layout of the
2915 /// given interface.
2917 /// \param Impl - If given, also include the layout of the interface's
2918 /// implementation. This may differ by including synthesized ivars.
2919 const ASTRecordLayout &
2920 ASTContext::getObjCLayout(const ObjCInterfaceDecl *D,
2921 const ObjCImplementationDecl *Impl) const {
2922 // Retrieve the definition
2923 if (D->hasExternalLexicalStorage() && !D->getDefinition())
2924 getExternalSource()->CompleteType(const_cast<ObjCInterfaceDecl*>(D));
2925 D = D->getDefinition();
2926 assert(D && D->isThisDeclarationADefinition() && "Invalid interface decl!");
2928 // Look up this layout, if already laid out, return what we have.
2929 const ObjCContainerDecl *Key =
2930 Impl ? (const ObjCContainerDecl*) Impl : (const ObjCContainerDecl*) D;
2931 if (const ASTRecordLayout *Entry = ObjCLayouts[Key])
2934 // Add in synthesized ivar count if laying out an implementation.
2936 unsigned SynthCount = CountNonClassIvars(D);
2937 // If there aren't any sythesized ivars then reuse the interface
2938 // entry. Note we can't cache this because we simply free all
2939 // entries later; however we shouldn't look up implementations
2941 if (SynthCount == 0)
2942 return getObjCLayout(D, nullptr);
2945 RecordLayoutBuilder Builder(*this, /*EmptySubobjects=*/nullptr);
2948 const ASTRecordLayout *NewEntry =
2949 new (*this) ASTRecordLayout(*this, Builder.getSize(),
2951 /*RequiredAlignment : used by MS-ABI)*/
2953 Builder.getDataSize(),
2954 Builder.FieldOffsets.data(),
2955 Builder.FieldOffsets.size());
2957 ObjCLayouts[Key] = NewEntry;
2962 static void PrintOffset(raw_ostream &OS,
2963 CharUnits Offset, unsigned IndentLevel) {
2964 OS << llvm::format("%4" PRId64 " | ", (int64_t)Offset.getQuantity());
2965 OS.indent(IndentLevel * 2);
2968 static void PrintIndentNoOffset(raw_ostream &OS, unsigned IndentLevel) {
2970 OS.indent(IndentLevel * 2);
2973 static void DumpCXXRecordLayout(raw_ostream &OS,
2974 const CXXRecordDecl *RD, const ASTContext &C,
2976 unsigned IndentLevel,
2977 const char* Description,
2978 bool IncludeVirtualBases) {
2979 const ASTRecordLayout &Layout = C.getASTRecordLayout(RD);
2981 PrintOffset(OS, Offset, IndentLevel);
2982 OS << C.getTypeDeclType(const_cast<CXXRecordDecl *>(RD)).getAsString();
2984 OS << ' ' << Description;
2991 const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
2992 bool HasOwnVFPtr = Layout.hasOwnVFPtr();
2993 bool HasOwnVBPtr = Layout.hasOwnVBPtr();
2996 if (RD->isDynamicClass() && !PrimaryBase && !isMsLayout(RD)) {
2997 PrintOffset(OS, Offset, IndentLevel);
2998 OS << '(' << *RD << " vtable pointer)\n";
2999 } else if (HasOwnVFPtr) {
3000 PrintOffset(OS, Offset, IndentLevel);
3001 // vfptr (for Microsoft C++ ABI)
3002 OS << '(' << *RD << " vftable pointer)\n";
3006 SmallVector<const CXXRecordDecl *, 4> Bases;
3007 for (const CXXBaseSpecifier &Base : RD->bases()) {
3008 assert(!Base.getType()->isDependentType() &&
3009 "Cannot layout class with dependent bases.");
3010 if (!Base.isVirtual())
3011 Bases.push_back(Base.getType()->getAsCXXRecordDecl());
3014 // Sort nvbases by offset.
3015 std::stable_sort(Bases.begin(), Bases.end(),
3016 [&](const CXXRecordDecl *L, const CXXRecordDecl *R) {
3017 return Layout.getBaseClassOffset(L) < Layout.getBaseClassOffset(R);
3020 // Dump (non-virtual) bases
3021 for (const CXXRecordDecl *Base : Bases) {
3022 CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base);
3023 DumpCXXRecordLayout(OS, Base, C, BaseOffset, IndentLevel,
3024 Base == PrimaryBase ? "(primary base)" : "(base)",
3025 /*IncludeVirtualBases=*/false);
3028 // vbptr (for Microsoft C++ ABI)
3030 PrintOffset(OS, Offset + Layout.getVBPtrOffset(), IndentLevel);
3031 OS << '(' << *RD << " vbtable pointer)\n";
3035 uint64_t FieldNo = 0;
3036 for (CXXRecordDecl::field_iterator I = RD->field_begin(),
3037 E = RD->field_end(); I != E; ++I, ++FieldNo) {
3038 const FieldDecl &Field = **I;
3039 CharUnits FieldOffset = Offset +
3040 C.toCharUnitsFromBits(Layout.getFieldOffset(FieldNo));
3042 if (const CXXRecordDecl *D = Field.getType()->getAsCXXRecordDecl()) {
3043 DumpCXXRecordLayout(OS, D, C, FieldOffset, IndentLevel,
3044 Field.getName().data(),
3045 /*IncludeVirtualBases=*/true);
3049 PrintOffset(OS, FieldOffset, IndentLevel);
3050 OS << Field.getType().getAsString() << ' ' << Field << '\n';
3053 if (!IncludeVirtualBases)
3056 // Dump virtual bases.
3057 const ASTRecordLayout::VBaseOffsetsMapTy &vtordisps =
3058 Layout.getVBaseOffsetsMap();
3059 for (const CXXBaseSpecifier &Base : RD->vbases()) {
3060 assert(Base.isVirtual() && "Found non-virtual class!");
3061 const CXXRecordDecl *VBase = Base.getType()->getAsCXXRecordDecl();
3063 CharUnits VBaseOffset = Offset + Layout.getVBaseClassOffset(VBase);
3065 if (vtordisps.find(VBase)->second.hasVtorDisp()) {
3066 PrintOffset(OS, VBaseOffset - CharUnits::fromQuantity(4), IndentLevel);
3067 OS << "(vtordisp for vbase " << *VBase << ")\n";
3070 DumpCXXRecordLayout(OS, VBase, C, VBaseOffset, IndentLevel,
3071 VBase == PrimaryBase ?
3072 "(primary virtual base)" : "(virtual base)",
3073 /*IncludeVirtualBases=*/false);
3076 PrintIndentNoOffset(OS, IndentLevel - 1);
3077 OS << "[sizeof=" << Layout.getSize().getQuantity();
3078 if (!isMsLayout(RD))
3079 OS << ", dsize=" << Layout.getDataSize().getQuantity();
3080 OS << ", align=" << Layout.getAlignment().getQuantity() << '\n';
3082 PrintIndentNoOffset(OS, IndentLevel - 1);
3083 OS << " nvsize=" << Layout.getNonVirtualSize().getQuantity();
3084 OS << ", nvalign=" << Layout.getNonVirtualAlignment().getQuantity() << "]\n";
3087 void ASTContext::DumpRecordLayout(const RecordDecl *RD,
3089 bool Simple) const {
3090 const ASTRecordLayout &Info = getASTRecordLayout(RD);
3092 if (const CXXRecordDecl *CXXRD = dyn_cast<CXXRecordDecl>(RD))
3094 return DumpCXXRecordLayout(OS, CXXRD, *this, CharUnits(), 0, nullptr,
3095 /*IncludeVirtualBases=*/true);
3097 OS << "Type: " << getTypeDeclType(RD).getAsString() << "\n";
3103 OS << "<ASTRecordLayout\n";
3104 OS << " Size:" << toBits(Info.getSize()) << "\n";
3105 if (!isMsLayout(RD))
3106 OS << " DataSize:" << toBits(Info.getDataSize()) << "\n";
3107 OS << " Alignment:" << toBits(Info.getAlignment()) << "\n";
3108 OS << " FieldOffsets: [";
3109 for (unsigned i = 0, e = Info.getFieldCount(); i != e; ++i) {
3111 OS << Info.getFieldOffset(i);