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 /// \brief Externally provided layout. Typically used when the AST source, such
59 /// as DWARF, lacks all the information that was available at compile time, such
60 /// as alignment attributes on fields and pragmas in effect.
61 struct ExternalLayout {
62 ExternalLayout() : Size(0), Align(0) {}
64 /// \brief Overall record size in bits.
67 /// \brief Overall record alignment in bits.
70 /// \brief Record field offsets in bits.
71 llvm::DenseMap<const FieldDecl *, uint64_t> FieldOffsets;
73 /// \brief Direct, non-virtual base offsets.
74 llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsets;
76 /// \brief Virtual base offsets.
77 llvm::DenseMap<const CXXRecordDecl *, CharUnits> VirtualBaseOffsets;
79 /// Get the offset of the given field. The external source must provide
80 /// entries for all fields in the record.
81 uint64_t getExternalFieldOffset(const FieldDecl *FD) {
82 assert(FieldOffsets.count(FD) &&
83 "Field does not have an external offset");
84 return FieldOffsets[FD];
87 bool getExternalNVBaseOffset(const CXXRecordDecl *RD, CharUnits &BaseOffset) {
88 auto Known = BaseOffsets.find(RD);
89 if (Known == BaseOffsets.end())
91 BaseOffset = Known->second;
95 bool getExternalVBaseOffset(const CXXRecordDecl *RD, CharUnits &BaseOffset) {
96 auto Known = VirtualBaseOffsets.find(RD);
97 if (Known == VirtualBaseOffsets.end())
99 BaseOffset = Known->second;
104 /// EmptySubobjectMap - Keeps track of which empty subobjects exist at different
105 /// offsets while laying out a C++ class.
106 class EmptySubobjectMap {
107 const ASTContext &Context;
110 /// Class - The class whose empty entries we're keeping track of.
111 const CXXRecordDecl *Class;
113 /// EmptyClassOffsets - A map from offsets to empty record decls.
114 typedef llvm::TinyPtrVector<const CXXRecordDecl *> ClassVectorTy;
115 typedef llvm::DenseMap<CharUnits, ClassVectorTy> EmptyClassOffsetsMapTy;
116 EmptyClassOffsetsMapTy EmptyClassOffsets;
118 /// MaxEmptyClassOffset - The highest offset known to contain an empty
120 CharUnits MaxEmptyClassOffset;
122 /// ComputeEmptySubobjectSizes - Compute the size of the largest base or
123 /// member subobject that is empty.
124 void ComputeEmptySubobjectSizes();
126 void AddSubobjectAtOffset(const CXXRecordDecl *RD, CharUnits Offset);
128 void UpdateEmptyBaseSubobjects(const BaseSubobjectInfo *Info,
129 CharUnits Offset, bool PlacingEmptyBase);
131 void UpdateEmptyFieldSubobjects(const CXXRecordDecl *RD,
132 const CXXRecordDecl *Class,
134 void UpdateEmptyFieldSubobjects(const FieldDecl *FD, CharUnits Offset);
136 /// AnyEmptySubobjectsBeyondOffset - Returns whether there are any empty
137 /// subobjects beyond the given offset.
138 bool AnyEmptySubobjectsBeyondOffset(CharUnits Offset) const {
139 return Offset <= MaxEmptyClassOffset;
143 getFieldOffset(const ASTRecordLayout &Layout, unsigned FieldNo) const {
144 uint64_t FieldOffset = Layout.getFieldOffset(FieldNo);
145 assert(FieldOffset % CharWidth == 0 &&
146 "Field offset not at char boundary!");
148 return Context.toCharUnitsFromBits(FieldOffset);
152 bool CanPlaceSubobjectAtOffset(const CXXRecordDecl *RD,
153 CharUnits Offset) const;
155 bool CanPlaceBaseSubobjectAtOffset(const BaseSubobjectInfo *Info,
158 bool CanPlaceFieldSubobjectAtOffset(const CXXRecordDecl *RD,
159 const CXXRecordDecl *Class,
160 CharUnits Offset) const;
161 bool CanPlaceFieldSubobjectAtOffset(const FieldDecl *FD,
162 CharUnits Offset) const;
165 /// This holds the size of the largest empty subobject (either a base
166 /// or a member). Will be zero if the record being built doesn't contain
167 /// any empty classes.
168 CharUnits SizeOfLargestEmptySubobject;
170 EmptySubobjectMap(const ASTContext &Context, const CXXRecordDecl *Class)
171 : Context(Context), CharWidth(Context.getCharWidth()), Class(Class) {
172 ComputeEmptySubobjectSizes();
175 /// CanPlaceBaseAtOffset - Return whether the given base class can be placed
176 /// at the given offset.
177 /// Returns false if placing the record will result in two components
178 /// (direct or indirect) of the same type having the same offset.
179 bool CanPlaceBaseAtOffset(const BaseSubobjectInfo *Info,
182 /// CanPlaceFieldAtOffset - Return whether a field can be placed at the given
184 bool CanPlaceFieldAtOffset(const FieldDecl *FD, CharUnits Offset);
187 void EmptySubobjectMap::ComputeEmptySubobjectSizes() {
189 for (const CXXBaseSpecifier &Base : Class->bases()) {
190 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
193 const ASTRecordLayout &Layout = Context.getASTRecordLayout(BaseDecl);
194 if (BaseDecl->isEmpty()) {
195 // If the class decl is empty, get its size.
196 EmptySize = Layout.getSize();
198 // Otherwise, we get the largest empty subobject for the decl.
199 EmptySize = Layout.getSizeOfLargestEmptySubobject();
202 if (EmptySize > SizeOfLargestEmptySubobject)
203 SizeOfLargestEmptySubobject = EmptySize;
207 for (const FieldDecl *FD : Class->fields()) {
208 const RecordType *RT =
209 Context.getBaseElementType(FD->getType())->getAs<RecordType>();
211 // We only care about record types.
216 const CXXRecordDecl *MemberDecl = RT->getAsCXXRecordDecl();
217 const ASTRecordLayout &Layout = Context.getASTRecordLayout(MemberDecl);
218 if (MemberDecl->isEmpty()) {
219 // If the class decl is empty, get its size.
220 EmptySize = Layout.getSize();
222 // Otherwise, we get the largest empty subobject for the decl.
223 EmptySize = Layout.getSizeOfLargestEmptySubobject();
226 if (EmptySize > SizeOfLargestEmptySubobject)
227 SizeOfLargestEmptySubobject = EmptySize;
232 EmptySubobjectMap::CanPlaceSubobjectAtOffset(const CXXRecordDecl *RD,
233 CharUnits Offset) const {
234 // We only need to check empty bases.
238 EmptyClassOffsetsMapTy::const_iterator I = EmptyClassOffsets.find(Offset);
239 if (I == EmptyClassOffsets.end())
242 const ClassVectorTy &Classes = I->second;
243 if (std::find(Classes.begin(), Classes.end(), RD) == Classes.end())
246 // There is already an empty class of the same type at this offset.
250 void EmptySubobjectMap::AddSubobjectAtOffset(const CXXRecordDecl *RD,
252 // We only care about empty bases.
256 // If we have empty structures inside a union, we can assign both
257 // the same offset. Just avoid pushing them twice in the list.
258 ClassVectorTy &Classes = EmptyClassOffsets[Offset];
259 if (std::find(Classes.begin(), Classes.end(), RD) != Classes.end())
262 Classes.push_back(RD);
264 // Update the empty class offset.
265 if (Offset > MaxEmptyClassOffset)
266 MaxEmptyClassOffset = Offset;
270 EmptySubobjectMap::CanPlaceBaseSubobjectAtOffset(const BaseSubobjectInfo *Info,
272 // We don't have to keep looking past the maximum offset that's known to
273 // contain an empty class.
274 if (!AnyEmptySubobjectsBeyondOffset(Offset))
277 if (!CanPlaceSubobjectAtOffset(Info->Class, Offset))
280 // Traverse all non-virtual bases.
281 const ASTRecordLayout &Layout = Context.getASTRecordLayout(Info->Class);
282 for (const BaseSubobjectInfo *Base : Info->Bases) {
286 CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base->Class);
288 if (!CanPlaceBaseSubobjectAtOffset(Base, BaseOffset))
292 if (Info->PrimaryVirtualBaseInfo) {
293 BaseSubobjectInfo *PrimaryVirtualBaseInfo = Info->PrimaryVirtualBaseInfo;
295 if (Info == PrimaryVirtualBaseInfo->Derived) {
296 if (!CanPlaceBaseSubobjectAtOffset(PrimaryVirtualBaseInfo, Offset))
301 // Traverse all member variables.
302 unsigned FieldNo = 0;
303 for (CXXRecordDecl::field_iterator I = Info->Class->field_begin(),
304 E = Info->Class->field_end(); I != E; ++I, ++FieldNo) {
308 CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
309 if (!CanPlaceFieldSubobjectAtOffset(*I, FieldOffset))
316 void EmptySubobjectMap::UpdateEmptyBaseSubobjects(const BaseSubobjectInfo *Info,
318 bool PlacingEmptyBase) {
319 if (!PlacingEmptyBase && Offset >= SizeOfLargestEmptySubobject) {
320 // We know that the only empty subobjects that can conflict with empty
321 // subobject of non-empty bases, are empty bases that can be placed at
322 // offset zero. Because of this, we only need to keep track of empty base
323 // subobjects with offsets less than the size of the largest empty
324 // subobject for our class.
328 AddSubobjectAtOffset(Info->Class, Offset);
330 // Traverse all non-virtual bases.
331 const ASTRecordLayout &Layout = Context.getASTRecordLayout(Info->Class);
332 for (const BaseSubobjectInfo *Base : Info->Bases) {
336 CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base->Class);
337 UpdateEmptyBaseSubobjects(Base, BaseOffset, PlacingEmptyBase);
340 if (Info->PrimaryVirtualBaseInfo) {
341 BaseSubobjectInfo *PrimaryVirtualBaseInfo = Info->PrimaryVirtualBaseInfo;
343 if (Info == PrimaryVirtualBaseInfo->Derived)
344 UpdateEmptyBaseSubobjects(PrimaryVirtualBaseInfo, Offset,
348 // Traverse all member variables.
349 unsigned FieldNo = 0;
350 for (CXXRecordDecl::field_iterator I = Info->Class->field_begin(),
351 E = Info->Class->field_end(); I != E; ++I, ++FieldNo) {
355 CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
356 UpdateEmptyFieldSubobjects(*I, FieldOffset);
360 bool EmptySubobjectMap::CanPlaceBaseAtOffset(const BaseSubobjectInfo *Info,
362 // If we know this class doesn't have any empty subobjects we don't need to
364 if (SizeOfLargestEmptySubobject.isZero())
367 if (!CanPlaceBaseSubobjectAtOffset(Info, Offset))
370 // We are able to place the base at this offset. Make sure to update the
371 // empty base subobject map.
372 UpdateEmptyBaseSubobjects(Info, Offset, Info->Class->isEmpty());
377 EmptySubobjectMap::CanPlaceFieldSubobjectAtOffset(const CXXRecordDecl *RD,
378 const CXXRecordDecl *Class,
379 CharUnits Offset) const {
380 // We don't have to keep looking past the maximum offset that's known to
381 // contain an empty class.
382 if (!AnyEmptySubobjectsBeyondOffset(Offset))
385 if (!CanPlaceSubobjectAtOffset(RD, Offset))
388 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
390 // Traverse all non-virtual bases.
391 for (const CXXBaseSpecifier &Base : RD->bases()) {
392 if (Base.isVirtual())
395 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
397 CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(BaseDecl);
398 if (!CanPlaceFieldSubobjectAtOffset(BaseDecl, Class, BaseOffset))
403 // This is the most derived class, traverse virtual bases as well.
404 for (const CXXBaseSpecifier &Base : RD->vbases()) {
405 const CXXRecordDecl *VBaseDecl = Base.getType()->getAsCXXRecordDecl();
407 CharUnits VBaseOffset = Offset + Layout.getVBaseClassOffset(VBaseDecl);
408 if (!CanPlaceFieldSubobjectAtOffset(VBaseDecl, Class, VBaseOffset))
413 // Traverse all member variables.
414 unsigned FieldNo = 0;
415 for (CXXRecordDecl::field_iterator I = RD->field_begin(), E = RD->field_end();
416 I != E; ++I, ++FieldNo) {
420 CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
422 if (!CanPlaceFieldSubobjectAtOffset(*I, FieldOffset))
430 EmptySubobjectMap::CanPlaceFieldSubobjectAtOffset(const FieldDecl *FD,
431 CharUnits Offset) const {
432 // We don't have to keep looking past the maximum offset that's known to
433 // contain an empty class.
434 if (!AnyEmptySubobjectsBeyondOffset(Offset))
437 QualType T = FD->getType();
438 if (const CXXRecordDecl *RD = T->getAsCXXRecordDecl())
439 return CanPlaceFieldSubobjectAtOffset(RD, RD, Offset);
441 // If we have an array type we need to look at every element.
442 if (const ConstantArrayType *AT = Context.getAsConstantArrayType(T)) {
443 QualType ElemTy = Context.getBaseElementType(AT);
444 const RecordType *RT = ElemTy->getAs<RecordType>();
448 const CXXRecordDecl *RD = RT->getAsCXXRecordDecl();
449 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
451 uint64_t NumElements = Context.getConstantArrayElementCount(AT);
452 CharUnits ElementOffset = Offset;
453 for (uint64_t I = 0; I != NumElements; ++I) {
454 // We don't have to keep looking past the maximum offset that's known to
455 // contain an empty class.
456 if (!AnyEmptySubobjectsBeyondOffset(ElementOffset))
459 if (!CanPlaceFieldSubobjectAtOffset(RD, RD, ElementOffset))
462 ElementOffset += Layout.getSize();
470 EmptySubobjectMap::CanPlaceFieldAtOffset(const FieldDecl *FD,
472 if (!CanPlaceFieldSubobjectAtOffset(FD, Offset))
475 // We are able to place the member variable at this offset.
476 // Make sure to update the empty base subobject map.
477 UpdateEmptyFieldSubobjects(FD, Offset);
481 void EmptySubobjectMap::UpdateEmptyFieldSubobjects(const CXXRecordDecl *RD,
482 const CXXRecordDecl *Class,
484 // We know that the only empty subobjects that can conflict with empty
485 // field subobjects are subobjects of empty bases that can be placed at offset
486 // zero. Because of this, we only need to keep track of empty field
487 // subobjects with offsets less than the size of the largest empty
488 // subobject for our class.
489 if (Offset >= SizeOfLargestEmptySubobject)
492 AddSubobjectAtOffset(RD, Offset);
494 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
496 // Traverse all non-virtual bases.
497 for (const CXXBaseSpecifier &Base : RD->bases()) {
498 if (Base.isVirtual())
501 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
503 CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(BaseDecl);
504 UpdateEmptyFieldSubobjects(BaseDecl, Class, BaseOffset);
508 // This is the most derived class, traverse virtual bases as well.
509 for (const CXXBaseSpecifier &Base : RD->vbases()) {
510 const CXXRecordDecl *VBaseDecl = Base.getType()->getAsCXXRecordDecl();
512 CharUnits VBaseOffset = Offset + Layout.getVBaseClassOffset(VBaseDecl);
513 UpdateEmptyFieldSubobjects(VBaseDecl, Class, VBaseOffset);
517 // Traverse all member variables.
518 unsigned FieldNo = 0;
519 for (CXXRecordDecl::field_iterator I = RD->field_begin(), E = RD->field_end();
520 I != E; ++I, ++FieldNo) {
524 CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
526 UpdateEmptyFieldSubobjects(*I, FieldOffset);
530 void EmptySubobjectMap::UpdateEmptyFieldSubobjects(const FieldDecl *FD,
532 QualType T = FD->getType();
533 if (const CXXRecordDecl *RD = T->getAsCXXRecordDecl()) {
534 UpdateEmptyFieldSubobjects(RD, RD, Offset);
538 // If we have an array type we need to update every element.
539 if (const ConstantArrayType *AT = Context.getAsConstantArrayType(T)) {
540 QualType ElemTy = Context.getBaseElementType(AT);
541 const RecordType *RT = ElemTy->getAs<RecordType>();
545 const CXXRecordDecl *RD = RT->getAsCXXRecordDecl();
546 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
548 uint64_t NumElements = Context.getConstantArrayElementCount(AT);
549 CharUnits ElementOffset = Offset;
551 for (uint64_t I = 0; I != NumElements; ++I) {
552 // We know that the only empty subobjects that can conflict with empty
553 // field subobjects are subobjects of empty bases that can be placed at
554 // offset zero. Because of this, we only need to keep track of empty field
555 // subobjects with offsets less than the size of the largest empty
556 // subobject for our class.
557 if (ElementOffset >= SizeOfLargestEmptySubobject)
560 UpdateEmptyFieldSubobjects(RD, RD, ElementOffset);
561 ElementOffset += Layout.getSize();
566 typedef llvm::SmallPtrSet<const CXXRecordDecl*, 4> ClassSetTy;
568 class RecordLayoutBuilder {
570 // FIXME: Remove this and make the appropriate fields public.
571 friend class clang::ASTContext;
573 const ASTContext &Context;
575 EmptySubobjectMap *EmptySubobjects;
577 /// Size - The current size of the record layout.
580 /// Alignment - The current alignment of the record layout.
583 /// \brief The alignment if attribute packed is not used.
584 CharUnits UnpackedAlignment;
586 SmallVector<uint64_t, 16> FieldOffsets;
588 /// \brief Whether the external AST source has provided a layout for this
590 unsigned UseExternalLayout : 1;
592 /// \brief Whether we need to infer alignment, even when we have an
593 /// externally-provided layout.
594 unsigned InferAlignment : 1;
596 /// Packed - Whether the record is packed or not.
599 unsigned IsUnion : 1;
601 unsigned IsMac68kAlign : 1;
603 unsigned IsMsStruct : 1;
605 /// UnfilledBitsInLastUnit - If the last field laid out was a bitfield,
606 /// this contains the number of bits in the last unit that can be used for
607 /// an adjacent bitfield if necessary. The unit in question is usually
608 /// a byte, but larger units are used if IsMsStruct.
609 unsigned char UnfilledBitsInLastUnit;
610 /// LastBitfieldTypeSize - If IsMsStruct, represents the size of the type
611 /// of the previous field if it was a bitfield.
612 unsigned char LastBitfieldTypeSize;
614 /// MaxFieldAlignment - The maximum allowed field alignment. This is set by
616 CharUnits MaxFieldAlignment;
618 /// DataSize - The data size of the record being laid out.
621 CharUnits NonVirtualSize;
622 CharUnits NonVirtualAlignment;
624 /// PrimaryBase - the primary base class (if one exists) of the class
625 /// we're laying out.
626 const CXXRecordDecl *PrimaryBase;
628 /// PrimaryBaseIsVirtual - Whether the primary base of the class we're laying
630 bool PrimaryBaseIsVirtual;
632 /// HasOwnVFPtr - Whether the class provides its own vtable/vftbl
633 /// pointer, as opposed to inheriting one from a primary base class.
636 typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsetsMapTy;
638 /// Bases - base classes and their offsets in the record.
639 BaseOffsetsMapTy Bases;
641 // VBases - virtual base classes and their offsets in the record.
642 ASTRecordLayout::VBaseOffsetsMapTy VBases;
644 /// IndirectPrimaryBases - Virtual base classes, direct or indirect, that are
645 /// primary base classes for some other direct or indirect base class.
646 CXXIndirectPrimaryBaseSet IndirectPrimaryBases;
648 /// FirstNearlyEmptyVBase - The first nearly empty virtual base class in
649 /// inheritance graph order. Used for determining the primary base class.
650 const CXXRecordDecl *FirstNearlyEmptyVBase;
652 /// VisitedVirtualBases - A set of all the visited virtual bases, used to
653 /// avoid visiting virtual bases more than once.
654 llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBases;
656 /// Valid if UseExternalLayout is true.
657 ExternalLayout External;
659 RecordLayoutBuilder(const ASTContext &Context,
660 EmptySubobjectMap *EmptySubobjects)
661 : Context(Context), EmptySubobjects(EmptySubobjects), Size(0),
662 Alignment(CharUnits::One()), UnpackedAlignment(CharUnits::One()),
663 UseExternalLayout(false), InferAlignment(false),
664 Packed(false), IsUnion(false), IsMac68kAlign(false), IsMsStruct(false),
665 UnfilledBitsInLastUnit(0), LastBitfieldTypeSize(0),
666 MaxFieldAlignment(CharUnits::Zero()),
667 DataSize(0), NonVirtualSize(CharUnits::Zero()),
668 NonVirtualAlignment(CharUnits::One()),
669 PrimaryBase(nullptr), PrimaryBaseIsVirtual(false),
671 FirstNearlyEmptyVBase(nullptr) {}
673 void Layout(const RecordDecl *D);
674 void Layout(const CXXRecordDecl *D);
675 void Layout(const ObjCInterfaceDecl *D);
677 void LayoutFields(const RecordDecl *D);
678 void LayoutField(const FieldDecl *D, bool InsertExtraPadding);
679 void LayoutWideBitField(uint64_t FieldSize, uint64_t TypeSize,
680 bool FieldPacked, const FieldDecl *D);
681 void LayoutBitField(const FieldDecl *D);
683 TargetCXXABI getCXXABI() const {
684 return Context.getTargetInfo().getCXXABI();
687 /// BaseSubobjectInfoAllocator - Allocator for BaseSubobjectInfo objects.
688 llvm::SpecificBumpPtrAllocator<BaseSubobjectInfo> BaseSubobjectInfoAllocator;
690 typedef llvm::DenseMap<const CXXRecordDecl *, BaseSubobjectInfo *>
691 BaseSubobjectInfoMapTy;
693 /// VirtualBaseInfo - Map from all the (direct or indirect) virtual bases
694 /// of the class we're laying out to their base subobject info.
695 BaseSubobjectInfoMapTy VirtualBaseInfo;
697 /// NonVirtualBaseInfo - Map from all the direct non-virtual bases of the
698 /// class we're laying out to their base subobject info.
699 BaseSubobjectInfoMapTy NonVirtualBaseInfo;
701 /// ComputeBaseSubobjectInfo - Compute the base subobject information for the
702 /// bases of the given class.
703 void ComputeBaseSubobjectInfo(const CXXRecordDecl *RD);
705 /// ComputeBaseSubobjectInfo - Compute the base subobject information for a
706 /// single class and all of its base classes.
707 BaseSubobjectInfo *ComputeBaseSubobjectInfo(const CXXRecordDecl *RD,
709 BaseSubobjectInfo *Derived);
711 /// DeterminePrimaryBase - Determine the primary base of the given class.
712 void DeterminePrimaryBase(const CXXRecordDecl *RD);
714 void SelectPrimaryVBase(const CXXRecordDecl *RD);
716 void EnsureVTablePointerAlignment(CharUnits UnpackedBaseAlign);
718 /// LayoutNonVirtualBases - Determines the primary base class (if any) and
719 /// lays it out. Will then proceed to lay out all non-virtual base clasess.
720 void LayoutNonVirtualBases(const CXXRecordDecl *RD);
722 /// LayoutNonVirtualBase - Lays out a single non-virtual base.
723 void LayoutNonVirtualBase(const BaseSubobjectInfo *Base);
725 void AddPrimaryVirtualBaseOffsets(const BaseSubobjectInfo *Info,
728 /// LayoutVirtualBases - Lays out all the virtual bases.
729 void LayoutVirtualBases(const CXXRecordDecl *RD,
730 const CXXRecordDecl *MostDerivedClass);
732 /// LayoutVirtualBase - Lays out a single virtual base.
733 void LayoutVirtualBase(const BaseSubobjectInfo *Base);
735 /// LayoutBase - Will lay out a base and return the offset where it was
736 /// placed, in chars.
737 CharUnits LayoutBase(const BaseSubobjectInfo *Base);
739 /// InitializeLayout - Initialize record layout for the given record decl.
740 void InitializeLayout(const Decl *D);
742 /// FinishLayout - Finalize record layout. Adjust record size based on the
744 void FinishLayout(const NamedDecl *D);
746 void UpdateAlignment(CharUnits NewAlignment, CharUnits UnpackedNewAlignment);
747 void UpdateAlignment(CharUnits NewAlignment) {
748 UpdateAlignment(NewAlignment, NewAlignment);
751 /// \brief Retrieve the externally-supplied field offset for the given
754 /// \param Field The field whose offset is being queried.
755 /// \param ComputedOffset The offset that we've computed for this field.
756 uint64_t updateExternalFieldOffset(const FieldDecl *Field,
757 uint64_t ComputedOffset);
759 void CheckFieldPadding(uint64_t Offset, uint64_t UnpaddedOffset,
760 uint64_t UnpackedOffset, unsigned UnpackedAlign,
761 bool isPacked, const FieldDecl *D);
763 DiagnosticBuilder Diag(SourceLocation Loc, unsigned DiagID);
765 CharUnits getSize() const {
766 assert(Size % Context.getCharWidth() == 0);
767 return Context.toCharUnitsFromBits(Size);
769 uint64_t getSizeInBits() const { return Size; }
771 void setSize(CharUnits NewSize) { Size = Context.toBits(NewSize); }
772 void setSize(uint64_t NewSize) { Size = NewSize; }
774 CharUnits getAligment() const { return Alignment; }
776 CharUnits getDataSize() const {
777 assert(DataSize % Context.getCharWidth() == 0);
778 return Context.toCharUnitsFromBits(DataSize);
780 uint64_t getDataSizeInBits() const { return DataSize; }
782 void setDataSize(CharUnits NewSize) { DataSize = Context.toBits(NewSize); }
783 void setDataSize(uint64_t NewSize) { DataSize = NewSize; }
785 RecordLayoutBuilder(const RecordLayoutBuilder &) = delete;
786 void operator=(const RecordLayoutBuilder &) = delete;
788 } // end anonymous namespace
791 RecordLayoutBuilder::SelectPrimaryVBase(const CXXRecordDecl *RD) {
792 for (const auto &I : RD->bases()) {
793 assert(!I.getType()->isDependentType() &&
794 "Cannot layout class with dependent bases.");
796 const CXXRecordDecl *Base = I.getType()->getAsCXXRecordDecl();
798 // Check if this is a nearly empty virtual base.
799 if (I.isVirtual() && Context.isNearlyEmpty(Base)) {
800 // If it's not an indirect primary base, then we've found our primary
802 if (!IndirectPrimaryBases.count(Base)) {
804 PrimaryBaseIsVirtual = true;
808 // Is this the first nearly empty virtual base?
809 if (!FirstNearlyEmptyVBase)
810 FirstNearlyEmptyVBase = Base;
813 SelectPrimaryVBase(Base);
819 /// DeterminePrimaryBase - Determine the primary base of the given class.
820 void RecordLayoutBuilder::DeterminePrimaryBase(const CXXRecordDecl *RD) {
821 // If the class isn't dynamic, it won't have a primary base.
822 if (!RD->isDynamicClass())
825 // Compute all the primary virtual bases for all of our direct and
826 // indirect bases, and record all their primary virtual base classes.
827 RD->getIndirectPrimaryBases(IndirectPrimaryBases);
829 // If the record has a dynamic base class, attempt to choose a primary base
830 // class. It is the first (in direct base class order) non-virtual dynamic
831 // base class, if one exists.
832 for (const auto &I : RD->bases()) {
833 // Ignore virtual bases.
837 const CXXRecordDecl *Base = I.getType()->getAsCXXRecordDecl();
839 if (Base->isDynamicClass()) {
842 PrimaryBaseIsVirtual = false;
847 // Under the Itanium ABI, if there is no non-virtual primary base class,
848 // try to compute the primary virtual base. The primary virtual base is
849 // the first nearly empty virtual base that is not an indirect primary
850 // virtual base class, if one exists.
851 if (RD->getNumVBases() != 0) {
852 SelectPrimaryVBase(RD);
857 // Otherwise, it is the first indirect primary base class, if one exists.
858 if (FirstNearlyEmptyVBase) {
859 PrimaryBase = FirstNearlyEmptyVBase;
860 PrimaryBaseIsVirtual = true;
864 assert(!PrimaryBase && "Should not get here with a primary base!");
868 RecordLayoutBuilder::ComputeBaseSubobjectInfo(const CXXRecordDecl *RD,
870 BaseSubobjectInfo *Derived) {
871 BaseSubobjectInfo *Info;
874 // Check if we already have info about this virtual base.
875 BaseSubobjectInfo *&InfoSlot = VirtualBaseInfo[RD];
877 assert(InfoSlot->Class == RD && "Wrong class for virtual base info!");
881 // We don't, create it.
882 InfoSlot = new (BaseSubobjectInfoAllocator.Allocate()) BaseSubobjectInfo;
885 Info = new (BaseSubobjectInfoAllocator.Allocate()) BaseSubobjectInfo;
889 Info->IsVirtual = IsVirtual;
890 Info->Derived = nullptr;
891 Info->PrimaryVirtualBaseInfo = nullptr;
893 const CXXRecordDecl *PrimaryVirtualBase = nullptr;
894 BaseSubobjectInfo *PrimaryVirtualBaseInfo = nullptr;
896 // Check if this base has a primary virtual base.
897 if (RD->getNumVBases()) {
898 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
899 if (Layout.isPrimaryBaseVirtual()) {
900 // This base does have a primary virtual base.
901 PrimaryVirtualBase = Layout.getPrimaryBase();
902 assert(PrimaryVirtualBase && "Didn't have a primary virtual base!");
904 // Now check if we have base subobject info about this primary base.
905 PrimaryVirtualBaseInfo = VirtualBaseInfo.lookup(PrimaryVirtualBase);
907 if (PrimaryVirtualBaseInfo) {
908 if (PrimaryVirtualBaseInfo->Derived) {
909 // We did have info about this primary base, and it turns out that it
910 // has already been claimed as a primary virtual base for another
912 PrimaryVirtualBase = nullptr;
914 // We can claim this base as our primary base.
915 Info->PrimaryVirtualBaseInfo = PrimaryVirtualBaseInfo;
916 PrimaryVirtualBaseInfo->Derived = Info;
922 // Now go through all direct bases.
923 for (const auto &I : RD->bases()) {
924 bool IsVirtual = I.isVirtual();
926 const CXXRecordDecl *BaseDecl = I.getType()->getAsCXXRecordDecl();
928 Info->Bases.push_back(ComputeBaseSubobjectInfo(BaseDecl, IsVirtual, Info));
931 if (PrimaryVirtualBase && !PrimaryVirtualBaseInfo) {
932 // Traversing the bases must have created the base info for our primary
934 PrimaryVirtualBaseInfo = VirtualBaseInfo.lookup(PrimaryVirtualBase);
935 assert(PrimaryVirtualBaseInfo &&
936 "Did not create a primary virtual base!");
938 // Claim the primary virtual base as our primary virtual base.
939 Info->PrimaryVirtualBaseInfo = PrimaryVirtualBaseInfo;
940 PrimaryVirtualBaseInfo->Derived = Info;
946 void RecordLayoutBuilder::ComputeBaseSubobjectInfo(const CXXRecordDecl *RD) {
947 for (const auto &I : RD->bases()) {
948 bool IsVirtual = I.isVirtual();
950 const CXXRecordDecl *BaseDecl = I.getType()->getAsCXXRecordDecl();
952 // Compute the base subobject info for this base.
953 BaseSubobjectInfo *Info = ComputeBaseSubobjectInfo(BaseDecl, IsVirtual,
957 // ComputeBaseInfo has already added this base for us.
958 assert(VirtualBaseInfo.count(BaseDecl) &&
959 "Did not add virtual base!");
961 // Add the base info to the map of non-virtual bases.
962 assert(!NonVirtualBaseInfo.count(BaseDecl) &&
963 "Non-virtual base already exists!");
964 NonVirtualBaseInfo.insert(std::make_pair(BaseDecl, Info));
970 RecordLayoutBuilder::EnsureVTablePointerAlignment(CharUnits UnpackedBaseAlign) {
971 CharUnits BaseAlign = (Packed) ? CharUnits::One() : UnpackedBaseAlign;
973 // The maximum field alignment overrides base align.
974 if (!MaxFieldAlignment.isZero()) {
975 BaseAlign = std::min(BaseAlign, MaxFieldAlignment);
976 UnpackedBaseAlign = std::min(UnpackedBaseAlign, MaxFieldAlignment);
979 // Round up the current record size to pointer alignment.
980 setSize(getSize().RoundUpToAlignment(BaseAlign));
981 setDataSize(getSize());
983 // Update the alignment.
984 UpdateAlignment(BaseAlign, UnpackedBaseAlign);
988 RecordLayoutBuilder::LayoutNonVirtualBases(const CXXRecordDecl *RD) {
989 // Then, determine the primary base class.
990 DeterminePrimaryBase(RD);
992 // Compute base subobject info.
993 ComputeBaseSubobjectInfo(RD);
995 // If we have a primary base class, lay it out.
997 if (PrimaryBaseIsVirtual) {
998 // If the primary virtual base was a primary virtual base of some other
999 // base class we'll have to steal it.
1000 BaseSubobjectInfo *PrimaryBaseInfo = VirtualBaseInfo.lookup(PrimaryBase);
1001 PrimaryBaseInfo->Derived = nullptr;
1003 // We have a virtual primary base, insert it as an indirect primary base.
1004 IndirectPrimaryBases.insert(PrimaryBase);
1006 assert(!VisitedVirtualBases.count(PrimaryBase) &&
1007 "vbase already visited!");
1008 VisitedVirtualBases.insert(PrimaryBase);
1010 LayoutVirtualBase(PrimaryBaseInfo);
1012 BaseSubobjectInfo *PrimaryBaseInfo =
1013 NonVirtualBaseInfo.lookup(PrimaryBase);
1014 assert(PrimaryBaseInfo &&
1015 "Did not find base info for non-virtual primary base!");
1017 LayoutNonVirtualBase(PrimaryBaseInfo);
1020 // If this class needs a vtable/vf-table and didn't get one from a
1021 // primary base, add it in now.
1022 } else if (RD->isDynamicClass()) {
1023 assert(DataSize == 0 && "Vtable pointer must be at offset zero!");
1024 CharUnits PtrWidth =
1025 Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
1026 CharUnits PtrAlign =
1027 Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerAlign(0));
1028 EnsureVTablePointerAlignment(PtrAlign);
1030 setSize(getSize() + PtrWidth);
1031 setDataSize(getSize());
1034 // Now lay out the non-virtual bases.
1035 for (const auto &I : RD->bases()) {
1037 // Ignore virtual bases.
1041 const CXXRecordDecl *BaseDecl = I.getType()->getAsCXXRecordDecl();
1043 // Skip the primary base, because we've already laid it out. The
1044 // !PrimaryBaseIsVirtual check is required because we might have a
1045 // non-virtual base of the same type as a primary virtual base.
1046 if (BaseDecl == PrimaryBase && !PrimaryBaseIsVirtual)
1049 // Lay out the base.
1050 BaseSubobjectInfo *BaseInfo = NonVirtualBaseInfo.lookup(BaseDecl);
1051 assert(BaseInfo && "Did not find base info for non-virtual base!");
1053 LayoutNonVirtualBase(BaseInfo);
1057 void RecordLayoutBuilder::LayoutNonVirtualBase(const BaseSubobjectInfo *Base) {
1059 CharUnits Offset = LayoutBase(Base);
1061 // Add its base class offset.
1062 assert(!Bases.count(Base->Class) && "base offset already exists!");
1063 Bases.insert(std::make_pair(Base->Class, Offset));
1065 AddPrimaryVirtualBaseOffsets(Base, Offset);
1069 RecordLayoutBuilder::AddPrimaryVirtualBaseOffsets(const BaseSubobjectInfo *Info,
1071 // This base isn't interesting, it has no virtual bases.
1072 if (!Info->Class->getNumVBases())
1075 // First, check if we have a virtual primary base to add offsets for.
1076 if (Info->PrimaryVirtualBaseInfo) {
1077 assert(Info->PrimaryVirtualBaseInfo->IsVirtual &&
1078 "Primary virtual base is not virtual!");
1079 if (Info->PrimaryVirtualBaseInfo->Derived == Info) {
1081 assert(!VBases.count(Info->PrimaryVirtualBaseInfo->Class) &&
1082 "primary vbase offset already exists!");
1083 VBases.insert(std::make_pair(Info->PrimaryVirtualBaseInfo->Class,
1084 ASTRecordLayout::VBaseInfo(Offset, false)));
1086 // Traverse the primary virtual base.
1087 AddPrimaryVirtualBaseOffsets(Info->PrimaryVirtualBaseInfo, Offset);
1091 // Now go through all direct non-virtual bases.
1092 const ASTRecordLayout &Layout = Context.getASTRecordLayout(Info->Class);
1093 for (const BaseSubobjectInfo *Base : Info->Bases) {
1094 if (Base->IsVirtual)
1097 CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base->Class);
1098 AddPrimaryVirtualBaseOffsets(Base, BaseOffset);
1103 RecordLayoutBuilder::LayoutVirtualBases(const CXXRecordDecl *RD,
1104 const CXXRecordDecl *MostDerivedClass) {
1105 const CXXRecordDecl *PrimaryBase;
1106 bool PrimaryBaseIsVirtual;
1108 if (MostDerivedClass == RD) {
1109 PrimaryBase = this->PrimaryBase;
1110 PrimaryBaseIsVirtual = this->PrimaryBaseIsVirtual;
1112 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1113 PrimaryBase = Layout.getPrimaryBase();
1114 PrimaryBaseIsVirtual = Layout.isPrimaryBaseVirtual();
1117 for (const CXXBaseSpecifier &Base : RD->bases()) {
1118 assert(!Base.getType()->isDependentType() &&
1119 "Cannot layout class with dependent bases.");
1121 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
1123 if (Base.isVirtual()) {
1124 if (PrimaryBase != BaseDecl || !PrimaryBaseIsVirtual) {
1125 bool IndirectPrimaryBase = IndirectPrimaryBases.count(BaseDecl);
1127 // Only lay out the virtual base if it's not an indirect primary base.
1128 if (!IndirectPrimaryBase) {
1129 // Only visit virtual bases once.
1130 if (!VisitedVirtualBases.insert(BaseDecl).second)
1133 const BaseSubobjectInfo *BaseInfo = VirtualBaseInfo.lookup(BaseDecl);
1134 assert(BaseInfo && "Did not find virtual base info!");
1135 LayoutVirtualBase(BaseInfo);
1140 if (!BaseDecl->getNumVBases()) {
1141 // This base isn't interesting since it doesn't have any virtual bases.
1145 LayoutVirtualBases(BaseDecl, MostDerivedClass);
1149 void RecordLayoutBuilder::LayoutVirtualBase(const BaseSubobjectInfo *Base) {
1150 assert(!Base->Derived && "Trying to lay out a primary virtual base!");
1153 CharUnits Offset = LayoutBase(Base);
1155 // Add its base class offset.
1156 assert(!VBases.count(Base->Class) && "vbase offset already exists!");
1157 VBases.insert(std::make_pair(Base->Class,
1158 ASTRecordLayout::VBaseInfo(Offset, false)));
1160 AddPrimaryVirtualBaseOffsets(Base, Offset);
1163 CharUnits RecordLayoutBuilder::LayoutBase(const BaseSubobjectInfo *Base) {
1164 const ASTRecordLayout &Layout = Context.getASTRecordLayout(Base->Class);
1169 // Query the external layout to see if it provides an offset.
1170 bool HasExternalLayout = false;
1171 if (UseExternalLayout) {
1172 llvm::DenseMap<const CXXRecordDecl *, CharUnits>::iterator Known;
1173 if (Base->IsVirtual)
1174 HasExternalLayout = External.getExternalNVBaseOffset(Base->Class, Offset);
1176 HasExternalLayout = External.getExternalVBaseOffset(Base->Class, Offset);
1179 CharUnits UnpackedBaseAlign = Layout.getNonVirtualAlignment();
1180 CharUnits BaseAlign = (Packed) ? CharUnits::One() : UnpackedBaseAlign;
1182 // If we have an empty base class, try to place it at offset 0.
1183 if (Base->Class->isEmpty() &&
1184 (!HasExternalLayout || Offset == CharUnits::Zero()) &&
1185 EmptySubobjects->CanPlaceBaseAtOffset(Base, CharUnits::Zero())) {
1186 setSize(std::max(getSize(), Layout.getSize()));
1187 UpdateAlignment(BaseAlign, UnpackedBaseAlign);
1189 return CharUnits::Zero();
1192 // The maximum field alignment overrides base align.
1193 if (!MaxFieldAlignment.isZero()) {
1194 BaseAlign = std::min(BaseAlign, MaxFieldAlignment);
1195 UnpackedBaseAlign = std::min(UnpackedBaseAlign, MaxFieldAlignment);
1198 if (!HasExternalLayout) {
1199 // Round up the current record size to the base's alignment boundary.
1200 Offset = getDataSize().RoundUpToAlignment(BaseAlign);
1202 // Try to place the base.
1203 while (!EmptySubobjects->CanPlaceBaseAtOffset(Base, Offset))
1204 Offset += BaseAlign;
1206 bool Allowed = EmptySubobjects->CanPlaceBaseAtOffset(Base, Offset);
1208 assert(Allowed && "Base subobject externally placed at overlapping offset");
1210 if (InferAlignment && Offset < getDataSize().RoundUpToAlignment(BaseAlign)){
1211 // The externally-supplied base offset is before the base offset we
1212 // computed. Assume that the structure is packed.
1213 Alignment = CharUnits::One();
1214 InferAlignment = false;
1218 if (!Base->Class->isEmpty()) {
1219 // Update the data size.
1220 setDataSize(Offset + Layout.getNonVirtualSize());
1222 setSize(std::max(getSize(), getDataSize()));
1224 setSize(std::max(getSize(), Offset + Layout.getSize()));
1226 // Remember max struct/class alignment.
1227 UpdateAlignment(BaseAlign, UnpackedBaseAlign);
1232 void RecordLayoutBuilder::InitializeLayout(const Decl *D) {
1233 if (const RecordDecl *RD = dyn_cast<RecordDecl>(D)) {
1234 IsUnion = RD->isUnion();
1235 IsMsStruct = RD->isMsStruct(Context);
1238 Packed = D->hasAttr<PackedAttr>();
1240 // Honor the default struct packing maximum alignment flag.
1241 if (unsigned DefaultMaxFieldAlignment = Context.getLangOpts().PackStruct) {
1242 MaxFieldAlignment = CharUnits::fromQuantity(DefaultMaxFieldAlignment);
1245 // mac68k alignment supersedes maximum field alignment and attribute aligned,
1246 // and forces all structures to have 2-byte alignment. The IBM docs on it
1247 // allude to additional (more complicated) semantics, especially with regard
1248 // to bit-fields, but gcc appears not to follow that.
1249 if (D->hasAttr<AlignMac68kAttr>()) {
1250 IsMac68kAlign = true;
1251 MaxFieldAlignment = CharUnits::fromQuantity(2);
1252 Alignment = CharUnits::fromQuantity(2);
1254 if (const MaxFieldAlignmentAttr *MFAA = D->getAttr<MaxFieldAlignmentAttr>())
1255 MaxFieldAlignment = Context.toCharUnitsFromBits(MFAA->getAlignment());
1257 if (unsigned MaxAlign = D->getMaxAlignment())
1258 UpdateAlignment(Context.toCharUnitsFromBits(MaxAlign));
1261 // If there is an external AST source, ask it for the various offsets.
1262 if (const RecordDecl *RD = dyn_cast<RecordDecl>(D))
1263 if (ExternalASTSource *Source = Context.getExternalSource()) {
1264 UseExternalLayout = Source->layoutRecordType(
1265 RD, External.Size, External.Align, External.FieldOffsets,
1266 External.BaseOffsets, External.VirtualBaseOffsets);
1268 // Update based on external alignment.
1269 if (UseExternalLayout) {
1270 if (External.Align > 0) {
1271 Alignment = Context.toCharUnitsFromBits(External.Align);
1273 // The external source didn't have alignment information; infer it.
1274 InferAlignment = true;
1280 void RecordLayoutBuilder::Layout(const RecordDecl *D) {
1281 InitializeLayout(D);
1284 // Finally, round the size of the total struct up to the alignment of the
1289 void RecordLayoutBuilder::Layout(const CXXRecordDecl *RD) {
1290 InitializeLayout(RD);
1292 // Lay out the vtable and the non-virtual bases.
1293 LayoutNonVirtualBases(RD);
1297 NonVirtualSize = Context.toCharUnitsFromBits(
1298 llvm::RoundUpToAlignment(getSizeInBits(),
1299 Context.getTargetInfo().getCharAlign()));
1300 NonVirtualAlignment = Alignment;
1302 // Lay out the virtual bases and add the primary virtual base offsets.
1303 LayoutVirtualBases(RD, RD);
1305 // Finally, round the size of the total struct up to the alignment
1306 // of the struct itself.
1310 // Check that we have base offsets for all bases.
1311 for (const CXXBaseSpecifier &Base : RD->bases()) {
1312 if (Base.isVirtual())
1315 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
1317 assert(Bases.count(BaseDecl) && "Did not find base offset!");
1320 // And all virtual bases.
1321 for (const CXXBaseSpecifier &Base : RD->vbases()) {
1322 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
1324 assert(VBases.count(BaseDecl) && "Did not find base offset!");
1329 void RecordLayoutBuilder::Layout(const ObjCInterfaceDecl *D) {
1330 if (ObjCInterfaceDecl *SD = D->getSuperClass()) {
1331 const ASTRecordLayout &SL = Context.getASTObjCInterfaceLayout(SD);
1333 UpdateAlignment(SL.getAlignment());
1335 // We start laying out ivars not at the end of the superclass
1336 // structure, but at the next byte following the last field.
1337 setSize(SL.getDataSize());
1338 setDataSize(getSize());
1341 InitializeLayout(D);
1342 // Layout each ivar sequentially.
1343 for (const ObjCIvarDecl *IVD = D->all_declared_ivar_begin(); IVD;
1344 IVD = IVD->getNextIvar())
1345 LayoutField(IVD, false);
1347 // Finally, round the size of the total struct up to the alignment of the
1352 void RecordLayoutBuilder::LayoutFields(const RecordDecl *D) {
1353 // Layout each field, for now, just sequentially, respecting alignment. In
1354 // the future, this will need to be tweakable by targets.
1355 bool InsertExtraPadding = D->mayInsertExtraPadding(/*EmitRemark=*/true);
1356 bool HasFlexibleArrayMember = D->hasFlexibleArrayMember();
1357 for (auto I = D->field_begin(), End = D->field_end(); I != End; ++I) {
1361 InsertExtraPadding && (Next != End || !HasFlexibleArrayMember));
1365 // Rounds the specified size to have it a multiple of the char size.
1367 roundUpSizeToCharAlignment(uint64_t Size,
1368 const ASTContext &Context) {
1369 uint64_t CharAlignment = Context.getTargetInfo().getCharAlign();
1370 return llvm::RoundUpToAlignment(Size, CharAlignment);
1373 void RecordLayoutBuilder::LayoutWideBitField(uint64_t FieldSize,
1376 const FieldDecl *D) {
1377 assert(Context.getLangOpts().CPlusPlus &&
1378 "Can only have wide bit-fields in C++!");
1380 // Itanium C++ ABI 2.4:
1381 // If sizeof(T)*8 < n, let T' be the largest integral POD type with
1382 // sizeof(T')*8 <= n.
1384 QualType IntegralPODTypes[] = {
1385 Context.UnsignedCharTy, Context.UnsignedShortTy, Context.UnsignedIntTy,
1386 Context.UnsignedLongTy, Context.UnsignedLongLongTy
1390 for (const QualType &QT : IntegralPODTypes) {
1391 uint64_t Size = Context.getTypeSize(QT);
1393 if (Size > FieldSize)
1398 assert(!Type.isNull() && "Did not find a type!");
1400 CharUnits TypeAlign = Context.getTypeAlignInChars(Type);
1402 // We're not going to use any of the unfilled bits in the last byte.
1403 UnfilledBitsInLastUnit = 0;
1404 LastBitfieldTypeSize = 0;
1406 uint64_t FieldOffset;
1407 uint64_t UnpaddedFieldOffset = getDataSizeInBits() - UnfilledBitsInLastUnit;
1410 uint64_t RoundedFieldSize = roundUpSizeToCharAlignment(FieldSize,
1412 setDataSize(std::max(getDataSizeInBits(), RoundedFieldSize));
1415 // The bitfield is allocated starting at the next offset aligned
1416 // appropriately for T', with length n bits.
1417 FieldOffset = llvm::RoundUpToAlignment(getDataSizeInBits(),
1418 Context.toBits(TypeAlign));
1420 uint64_t NewSizeInBits = FieldOffset + FieldSize;
1422 setDataSize(llvm::RoundUpToAlignment(NewSizeInBits,
1423 Context.getTargetInfo().getCharAlign()));
1424 UnfilledBitsInLastUnit = getDataSizeInBits() - NewSizeInBits;
1427 // Place this field at the current location.
1428 FieldOffsets.push_back(FieldOffset);
1430 CheckFieldPadding(FieldOffset, UnpaddedFieldOffset, FieldOffset,
1431 Context.toBits(TypeAlign), FieldPacked, D);
1434 setSize(std::max(getSizeInBits(), getDataSizeInBits()));
1436 // Remember max struct/class alignment.
1437 UpdateAlignment(TypeAlign);
1440 void RecordLayoutBuilder::LayoutBitField(const FieldDecl *D) {
1441 bool FieldPacked = Packed || D->hasAttr<PackedAttr>();
1442 uint64_t FieldSize = D->getBitWidthValue(Context);
1443 TypeInfo FieldInfo = Context.getTypeInfo(D->getType());
1444 uint64_t TypeSize = FieldInfo.Width;
1445 unsigned FieldAlign = FieldInfo.Align;
1447 // UnfilledBitsInLastUnit is the difference between the end of the
1448 // last allocated bitfield (i.e. the first bit offset available for
1449 // bitfields) and the end of the current data size in bits (i.e. the
1450 // first bit offset available for non-bitfields). The current data
1451 // size in bits is always a multiple of the char size; additionally,
1452 // for ms_struct records it's also a multiple of the
1453 // LastBitfieldTypeSize (if set).
1455 // The struct-layout algorithm is dictated by the platform ABI,
1456 // which in principle could use almost any rules it likes. In
1457 // practice, UNIXy targets tend to inherit the algorithm described
1458 // in the System V generic ABI. The basic bitfield layout rule in
1459 // System V is to place bitfields at the next available bit offset
1460 // where the entire bitfield would fit in an aligned storage unit of
1461 // the declared type; it's okay if an earlier or later non-bitfield
1462 // is allocated in the same storage unit. However, some targets
1463 // (those that !useBitFieldTypeAlignment(), e.g. ARM APCS) don't
1464 // require this storage unit to be aligned, and therefore always put
1465 // the bitfield at the next available bit offset.
1467 // ms_struct basically requests a complete replacement of the
1468 // platform ABI's struct-layout algorithm, with the high-level goal
1469 // of duplicating MSVC's layout. For non-bitfields, this follows
1470 // the the standard algorithm. The basic bitfield layout rule is to
1471 // allocate an entire unit of the bitfield's declared type
1472 // (e.g. 'unsigned long'), then parcel it up among successive
1473 // bitfields whose declared types have the same size, making a new
1474 // unit as soon as the last can no longer store the whole value.
1475 // Since it completely replaces the platform ABI's algorithm,
1476 // settings like !useBitFieldTypeAlignment() do not apply.
1478 // A zero-width bitfield forces the use of a new storage unit for
1479 // later bitfields. In general, this occurs by rounding up the
1480 // current size of the struct as if the algorithm were about to
1481 // place a non-bitfield of the field's formal type. Usually this
1482 // does not change the alignment of the struct itself, but it does
1483 // on some targets (those that useZeroLengthBitfieldAlignment(),
1484 // e.g. ARM). In ms_struct layout, zero-width bitfields are
1485 // ignored unless they follow a non-zero-width bitfield.
1487 // A field alignment restriction (e.g. from #pragma pack) or
1488 // specification (e.g. from __attribute__((aligned))) changes the
1489 // formal alignment of the field. For System V, this alters the
1490 // required alignment of the notional storage unit that must contain
1491 // the bitfield. For ms_struct, this only affects the placement of
1492 // new storage units. In both cases, the effect of #pragma pack is
1493 // ignored on zero-width bitfields.
1495 // On System V, a packed field (e.g. from #pragma pack or
1496 // __attribute__((packed))) always uses the next available bit
1499 // In an ms_struct struct, the alignment of a fundamental type is
1500 // always equal to its size. This is necessary in order to mimic
1501 // the i386 alignment rules on targets which might not fully align
1502 // all types (e.g. Darwin PPC32, where alignof(long long) == 4).
1504 // First, some simple bookkeeping to perform for ms_struct structs.
1506 // The field alignment for integer types is always the size.
1507 FieldAlign = TypeSize;
1509 // If the previous field was not a bitfield, or was a bitfield
1510 // with a different storage unit size, we're done with that
1512 if (LastBitfieldTypeSize != TypeSize) {
1513 // Also, ignore zero-length bitfields after non-bitfields.
1514 if (!LastBitfieldTypeSize && !FieldSize)
1517 UnfilledBitsInLastUnit = 0;
1518 LastBitfieldTypeSize = 0;
1522 // If the field is wider than its declared type, it follows
1523 // different rules in all cases.
1524 if (FieldSize > TypeSize) {
1525 LayoutWideBitField(FieldSize, TypeSize, FieldPacked, D);
1529 // Compute the next available bit offset.
1530 uint64_t FieldOffset =
1531 IsUnion ? 0 : (getDataSizeInBits() - UnfilledBitsInLastUnit);
1533 // Handle targets that don't honor bitfield type alignment.
1534 if (!IsMsStruct && !Context.getTargetInfo().useBitFieldTypeAlignment()) {
1535 // Some such targets do honor it on zero-width bitfields.
1536 if (FieldSize == 0 &&
1537 Context.getTargetInfo().useZeroLengthBitfieldAlignment()) {
1538 // The alignment to round up to is the max of the field's natural
1539 // alignment and a target-specific fixed value (sometimes zero).
1540 unsigned ZeroLengthBitfieldBoundary =
1541 Context.getTargetInfo().getZeroLengthBitfieldBoundary();
1542 FieldAlign = std::max(FieldAlign, ZeroLengthBitfieldBoundary);
1544 // If that doesn't apply, just ignore the field alignment.
1550 // Remember the alignment we would have used if the field were not packed.
1551 unsigned UnpackedFieldAlign = FieldAlign;
1553 // Ignore the field alignment if the field is packed unless it has zero-size.
1554 if (!IsMsStruct && FieldPacked && FieldSize != 0)
1557 // But, if there's an 'aligned' attribute on the field, honor that.
1558 if (unsigned ExplicitFieldAlign = D->getMaxAlignment()) {
1559 FieldAlign = std::max(FieldAlign, ExplicitFieldAlign);
1560 UnpackedFieldAlign = std::max(UnpackedFieldAlign, ExplicitFieldAlign);
1563 // But, if there's a #pragma pack in play, that takes precedent over
1564 // even the 'aligned' attribute, for non-zero-width bitfields.
1565 if (!MaxFieldAlignment.isZero() && FieldSize) {
1566 unsigned MaxFieldAlignmentInBits = Context.toBits(MaxFieldAlignment);
1567 FieldAlign = std::min(FieldAlign, MaxFieldAlignmentInBits);
1568 UnpackedFieldAlign = std::min(UnpackedFieldAlign, MaxFieldAlignmentInBits);
1571 // For purposes of diagnostics, we're going to simultaneously
1572 // compute the field offsets that we would have used if we weren't
1573 // adding any alignment padding or if the field weren't packed.
1574 uint64_t UnpaddedFieldOffset = FieldOffset;
1575 uint64_t UnpackedFieldOffset = FieldOffset;
1577 // Check if we need to add padding to fit the bitfield within an
1578 // allocation unit with the right size and alignment. The rules are
1579 // somewhat different here for ms_struct structs.
1581 // If it's not a zero-width bitfield, and we can fit the bitfield
1582 // into the active storage unit (and we haven't already decided to
1583 // start a new storage unit), just do so, regardless of any other
1584 // other consideration. Otherwise, round up to the right alignment.
1585 if (FieldSize == 0 || FieldSize > UnfilledBitsInLastUnit) {
1586 FieldOffset = llvm::RoundUpToAlignment(FieldOffset, FieldAlign);
1587 UnpackedFieldOffset = llvm::RoundUpToAlignment(UnpackedFieldOffset,
1588 UnpackedFieldAlign);
1589 UnfilledBitsInLastUnit = 0;
1593 // #pragma pack, with any value, suppresses the insertion of padding.
1594 bool AllowPadding = MaxFieldAlignment.isZero();
1596 // Compute the real offset.
1597 if (FieldSize == 0 ||
1599 (FieldOffset & (FieldAlign-1)) + FieldSize > TypeSize)) {
1600 FieldOffset = llvm::RoundUpToAlignment(FieldOffset, FieldAlign);
1603 // Repeat the computation for diagnostic purposes.
1604 if (FieldSize == 0 ||
1606 (UnpackedFieldOffset & (UnpackedFieldAlign-1)) + FieldSize > TypeSize))
1607 UnpackedFieldOffset = llvm::RoundUpToAlignment(UnpackedFieldOffset,
1608 UnpackedFieldAlign);
1611 // If we're using external layout, give the external layout a chance
1612 // to override this information.
1613 if (UseExternalLayout)
1614 FieldOffset = updateExternalFieldOffset(D, FieldOffset);
1616 // Okay, place the bitfield at the calculated offset.
1617 FieldOffsets.push_back(FieldOffset);
1621 // Anonymous members don't affect the overall record alignment,
1622 // except on targets where they do.
1624 !Context.getTargetInfo().useZeroLengthBitfieldAlignment() &&
1625 !D->getIdentifier())
1626 FieldAlign = UnpackedFieldAlign = 1;
1628 // Diagnose differences in layout due to padding or packing.
1629 if (!UseExternalLayout)
1630 CheckFieldPadding(FieldOffset, UnpaddedFieldOffset, UnpackedFieldOffset,
1631 UnpackedFieldAlign, FieldPacked, D);
1633 // Update DataSize to include the last byte containing (part of) the bitfield.
1635 // For unions, this is just a max operation, as usual.
1637 uint64_t RoundedFieldSize = roundUpSizeToCharAlignment(FieldSize,
1639 setDataSize(std::max(getDataSizeInBits(), RoundedFieldSize));
1640 // For non-zero-width bitfields in ms_struct structs, allocate a new
1641 // storage unit if necessary.
1642 } else if (IsMsStruct && FieldSize) {
1643 // We should have cleared UnfilledBitsInLastUnit in every case
1644 // where we changed storage units.
1645 if (!UnfilledBitsInLastUnit) {
1646 setDataSize(FieldOffset + TypeSize);
1647 UnfilledBitsInLastUnit = TypeSize;
1649 UnfilledBitsInLastUnit -= FieldSize;
1650 LastBitfieldTypeSize = TypeSize;
1652 // Otherwise, bump the data size up to include the bitfield,
1653 // including padding up to char alignment, and then remember how
1654 // bits we didn't use.
1656 uint64_t NewSizeInBits = FieldOffset + FieldSize;
1657 uint64_t CharAlignment = Context.getTargetInfo().getCharAlign();
1658 setDataSize(llvm::RoundUpToAlignment(NewSizeInBits, CharAlignment));
1659 UnfilledBitsInLastUnit = getDataSizeInBits() - NewSizeInBits;
1661 // The only time we can get here for an ms_struct is if this is a
1662 // zero-width bitfield, which doesn't count as anything for the
1663 // purposes of unfilled bits.
1664 LastBitfieldTypeSize = 0;
1668 setSize(std::max(getSizeInBits(), getDataSizeInBits()));
1670 // Remember max struct/class alignment.
1671 UpdateAlignment(Context.toCharUnitsFromBits(FieldAlign),
1672 Context.toCharUnitsFromBits(UnpackedFieldAlign));
1675 void RecordLayoutBuilder::LayoutField(const FieldDecl *D,
1676 bool InsertExtraPadding) {
1677 if (D->isBitField()) {
1682 uint64_t UnpaddedFieldOffset = getDataSizeInBits() - UnfilledBitsInLastUnit;
1684 // Reset the unfilled bits.
1685 UnfilledBitsInLastUnit = 0;
1686 LastBitfieldTypeSize = 0;
1688 bool FieldPacked = Packed || D->hasAttr<PackedAttr>();
1689 CharUnits FieldOffset =
1690 IsUnion ? CharUnits::Zero() : getDataSize();
1691 CharUnits FieldSize;
1692 CharUnits FieldAlign;
1694 if (D->getType()->isIncompleteArrayType()) {
1695 // This is a flexible array member; we can't directly
1696 // query getTypeInfo about these, so we figure it out here.
1697 // Flexible array members don't have any size, but they
1698 // have to be aligned appropriately for their element type.
1699 FieldSize = CharUnits::Zero();
1700 const ArrayType* ATy = Context.getAsArrayType(D->getType());
1701 FieldAlign = Context.getTypeAlignInChars(ATy->getElementType());
1702 } else if (const ReferenceType *RT = D->getType()->getAs<ReferenceType>()) {
1703 unsigned AS = RT->getPointeeType().getAddressSpace();
1705 Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(AS));
1707 Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerAlign(AS));
1709 std::pair<CharUnits, CharUnits> FieldInfo =
1710 Context.getTypeInfoInChars(D->getType());
1711 FieldSize = FieldInfo.first;
1712 FieldAlign = FieldInfo.second;
1715 // If MS bitfield layout is required, figure out what type is being
1716 // laid out and align the field to the width of that type.
1718 // Resolve all typedefs down to their base type and round up the field
1719 // alignment if necessary.
1720 QualType T = Context.getBaseElementType(D->getType());
1721 if (const BuiltinType *BTy = T->getAs<BuiltinType>()) {
1722 CharUnits TypeSize = Context.getTypeSizeInChars(BTy);
1723 if (TypeSize > FieldAlign)
1724 FieldAlign = TypeSize;
1729 // The align if the field is not packed. This is to check if the attribute
1730 // was unnecessary (-Wpacked).
1731 CharUnits UnpackedFieldAlign = FieldAlign;
1732 CharUnits UnpackedFieldOffset = FieldOffset;
1735 FieldAlign = CharUnits::One();
1736 CharUnits MaxAlignmentInChars =
1737 Context.toCharUnitsFromBits(D->getMaxAlignment());
1738 FieldAlign = std::max(FieldAlign, MaxAlignmentInChars);
1739 UnpackedFieldAlign = std::max(UnpackedFieldAlign, MaxAlignmentInChars);
1741 // The maximum field alignment overrides the aligned attribute.
1742 if (!MaxFieldAlignment.isZero()) {
1743 FieldAlign = std::min(FieldAlign, MaxFieldAlignment);
1744 UnpackedFieldAlign = std::min(UnpackedFieldAlign, MaxFieldAlignment);
1747 // Round up the current record size to the field's alignment boundary.
1748 FieldOffset = FieldOffset.RoundUpToAlignment(FieldAlign);
1749 UnpackedFieldOffset =
1750 UnpackedFieldOffset.RoundUpToAlignment(UnpackedFieldAlign);
1752 if (UseExternalLayout) {
1753 FieldOffset = Context.toCharUnitsFromBits(
1754 updateExternalFieldOffset(D, Context.toBits(FieldOffset)));
1756 if (!IsUnion && EmptySubobjects) {
1757 // Record the fact that we're placing a field at this offset.
1758 bool Allowed = EmptySubobjects->CanPlaceFieldAtOffset(D, FieldOffset);
1760 assert(Allowed && "Externally-placed field cannot be placed here");
1763 if (!IsUnion && EmptySubobjects) {
1764 // Check if we can place the field at this offset.
1765 while (!EmptySubobjects->CanPlaceFieldAtOffset(D, FieldOffset)) {
1766 // We couldn't place the field at the offset. Try again at a new offset.
1767 FieldOffset += FieldAlign;
1772 // Place this field at the current location.
1773 FieldOffsets.push_back(Context.toBits(FieldOffset));
1775 if (!UseExternalLayout)
1776 CheckFieldPadding(Context.toBits(FieldOffset), UnpaddedFieldOffset,
1777 Context.toBits(UnpackedFieldOffset),
1778 Context.toBits(UnpackedFieldAlign), FieldPacked, D);
1780 if (InsertExtraPadding) {
1781 CharUnits ASanAlignment = CharUnits::fromQuantity(8);
1782 CharUnits ExtraSizeForAsan = ASanAlignment;
1783 if (FieldSize % ASanAlignment)
1785 ASanAlignment - CharUnits::fromQuantity(FieldSize % ASanAlignment);
1786 FieldSize += ExtraSizeForAsan;
1789 // Reserve space for this field.
1790 uint64_t FieldSizeInBits = Context.toBits(FieldSize);
1792 setDataSize(std::max(getDataSizeInBits(), FieldSizeInBits));
1794 setDataSize(FieldOffset + FieldSize);
1797 setSize(std::max(getSizeInBits(), getDataSizeInBits()));
1799 // Remember max struct/class alignment.
1800 UpdateAlignment(FieldAlign, UnpackedFieldAlign);
1803 void RecordLayoutBuilder::FinishLayout(const NamedDecl *D) {
1804 // In C++, records cannot be of size 0.
1805 if (Context.getLangOpts().CPlusPlus && getSizeInBits() == 0) {
1806 if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D)) {
1807 // Compatibility with gcc requires a class (pod or non-pod)
1808 // which is not empty but of size 0; such as having fields of
1809 // array of zero-length, remains of Size 0
1811 setSize(CharUnits::One());
1814 setSize(CharUnits::One());
1817 // Finally, round the size of the record up to the alignment of the
1819 uint64_t UnpaddedSize = getSizeInBits() - UnfilledBitsInLastUnit;
1820 uint64_t UnpackedSizeInBits =
1821 llvm::RoundUpToAlignment(getSizeInBits(),
1822 Context.toBits(UnpackedAlignment));
1823 CharUnits UnpackedSize = Context.toCharUnitsFromBits(UnpackedSizeInBits);
1824 uint64_t RoundedSize
1825 = llvm::RoundUpToAlignment(getSizeInBits(), Context.toBits(Alignment));
1827 if (UseExternalLayout) {
1828 // If we're inferring alignment, and the external size is smaller than
1829 // our size after we've rounded up to alignment, conservatively set the
1831 if (InferAlignment && External.Size < RoundedSize) {
1832 Alignment = CharUnits::One();
1833 InferAlignment = false;
1835 setSize(External.Size);
1839 // Set the size to the final size.
1840 setSize(RoundedSize);
1842 unsigned CharBitNum = Context.getTargetInfo().getCharWidth();
1843 if (const RecordDecl *RD = dyn_cast<RecordDecl>(D)) {
1844 // Warn if padding was introduced to the struct/class/union.
1845 if (getSizeInBits() > UnpaddedSize) {
1846 unsigned PadSize = getSizeInBits() - UnpaddedSize;
1848 if (PadSize % CharBitNum == 0) {
1849 PadSize = PadSize / CharBitNum;
1852 Diag(RD->getLocation(), diag::warn_padded_struct_size)
1853 << Context.getTypeDeclType(RD)
1855 << (InBits ? 1 : 0) /*(byte|bit)*/ << (PadSize > 1); // plural or not
1858 // Warn if we packed it unnecessarily. If the alignment is 1 byte don't
1859 // bother since there won't be alignment issues.
1860 if (Packed && UnpackedAlignment > CharUnits::One() &&
1861 getSize() == UnpackedSize)
1862 Diag(D->getLocation(), diag::warn_unnecessary_packed)
1863 << Context.getTypeDeclType(RD);
1867 void RecordLayoutBuilder::UpdateAlignment(CharUnits NewAlignment,
1868 CharUnits UnpackedNewAlignment) {
1869 // The alignment is not modified when using 'mac68k' alignment or when
1870 // we have an externally-supplied layout that also provides overall alignment.
1871 if (IsMac68kAlign || (UseExternalLayout && !InferAlignment))
1874 if (NewAlignment > Alignment) {
1875 assert(llvm::isPowerOf2_64(NewAlignment.getQuantity()) &&
1876 "Alignment not a power of 2");
1877 Alignment = NewAlignment;
1880 if (UnpackedNewAlignment > UnpackedAlignment) {
1881 assert(llvm::isPowerOf2_64(UnpackedNewAlignment.getQuantity()) &&
1882 "Alignment not a power of 2");
1883 UnpackedAlignment = UnpackedNewAlignment;
1888 RecordLayoutBuilder::updateExternalFieldOffset(const FieldDecl *Field,
1889 uint64_t ComputedOffset) {
1890 uint64_t ExternalFieldOffset = External.getExternalFieldOffset(Field);
1892 if (InferAlignment && ExternalFieldOffset < ComputedOffset) {
1893 // The externally-supplied field offset is before the field offset we
1894 // computed. Assume that the structure is packed.
1895 Alignment = CharUnits::One();
1896 InferAlignment = false;
1899 // Use the externally-supplied field offset.
1900 return ExternalFieldOffset;
1903 /// \brief Get diagnostic %select index for tag kind for
1904 /// field padding diagnostic message.
1905 /// WARNING: Indexes apply to particular diagnostics only!
1907 /// \returns diagnostic %select index.
1908 static unsigned getPaddingDiagFromTagKind(TagTypeKind Tag) {
1910 case TTK_Struct: return 0;
1911 case TTK_Interface: return 1;
1912 case TTK_Class: return 2;
1913 default: llvm_unreachable("Invalid tag kind for field padding diagnostic!");
1917 void RecordLayoutBuilder::CheckFieldPadding(uint64_t Offset,
1918 uint64_t UnpaddedOffset,
1919 uint64_t UnpackedOffset,
1920 unsigned UnpackedAlign,
1922 const FieldDecl *D) {
1923 // We let objc ivars without warning, objc interfaces generally are not used
1924 // for padding tricks.
1925 if (isa<ObjCIvarDecl>(D))
1928 // Don't warn about structs created without a SourceLocation. This can
1929 // be done by clients of the AST, such as codegen.
1930 if (D->getLocation().isInvalid())
1933 unsigned CharBitNum = Context.getTargetInfo().getCharWidth();
1935 // Warn if padding was introduced to the struct/class.
1936 if (!IsUnion && Offset > UnpaddedOffset) {
1937 unsigned PadSize = Offset - UnpaddedOffset;
1939 if (PadSize % CharBitNum == 0) {
1940 PadSize = PadSize / CharBitNum;
1943 if (D->getIdentifier())
1944 Diag(D->getLocation(), diag::warn_padded_struct_field)
1945 << getPaddingDiagFromTagKind(D->getParent()->getTagKind())
1946 << Context.getTypeDeclType(D->getParent())
1948 << (InBits ? 1 : 0) /*(byte|bit)*/ << (PadSize > 1) // plural or not
1949 << D->getIdentifier();
1951 Diag(D->getLocation(), diag::warn_padded_struct_anon_field)
1952 << getPaddingDiagFromTagKind(D->getParent()->getTagKind())
1953 << Context.getTypeDeclType(D->getParent())
1955 << (InBits ? 1 : 0) /*(byte|bit)*/ << (PadSize > 1); // plural or not
1958 // Warn if we packed it unnecessarily. If the alignment is 1 byte don't
1959 // bother since there won't be alignment issues.
1960 if (isPacked && UnpackedAlign > CharBitNum && Offset == UnpackedOffset)
1961 Diag(D->getLocation(), diag::warn_unnecessary_packed)
1962 << D->getIdentifier();
1965 static const CXXMethodDecl *computeKeyFunction(ASTContext &Context,
1966 const CXXRecordDecl *RD) {
1967 // If a class isn't polymorphic it doesn't have a key function.
1968 if (!RD->isPolymorphic())
1971 // A class that is not externally visible doesn't have a key function. (Or
1972 // at least, there's no point to assigning a key function to such a class;
1973 // this doesn't affect the ABI.)
1974 if (!RD->isExternallyVisible())
1977 // Template instantiations don't have key functions per Itanium C++ ABI 5.2.6.
1978 // Same behavior as GCC.
1979 TemplateSpecializationKind TSK = RD->getTemplateSpecializationKind();
1980 if (TSK == TSK_ImplicitInstantiation ||
1981 TSK == TSK_ExplicitInstantiationDeclaration ||
1982 TSK == TSK_ExplicitInstantiationDefinition)
1985 bool allowInlineFunctions =
1986 Context.getTargetInfo().getCXXABI().canKeyFunctionBeInline();
1988 for (const CXXMethodDecl *MD : RD->methods()) {
1989 if (!MD->isVirtual())
1995 // Ignore implicit member functions, they are always marked as inline, but
1996 // they don't have a body until they're defined.
1997 if (MD->isImplicit())
2000 if (MD->isInlineSpecified())
2003 if (MD->hasInlineBody())
2006 // Ignore inline deleted or defaulted functions.
2007 if (!MD->isUserProvided())
2010 // In certain ABIs, ignore functions with out-of-line inline definitions.
2011 if (!allowInlineFunctions) {
2012 const FunctionDecl *Def;
2013 if (MD->hasBody(Def) && Def->isInlineSpecified())
2025 RecordLayoutBuilder::Diag(SourceLocation Loc, unsigned DiagID) {
2026 return Context.getDiagnostics().Report(Loc, DiagID);
2029 /// Does the target C++ ABI require us to skip over the tail-padding
2030 /// of the given class (considering it as a base class) when allocating
2032 static bool mustSkipTailPadding(TargetCXXABI ABI, const CXXRecordDecl *RD) {
2033 switch (ABI.getTailPaddingUseRules()) {
2034 case TargetCXXABI::AlwaysUseTailPadding:
2037 case TargetCXXABI::UseTailPaddingUnlessPOD03:
2038 // FIXME: To the extent that this is meant to cover the Itanium ABI
2039 // rules, we should implement the restrictions about over-sized
2042 // http://mentorembedded.github.com/cxx-abi/abi.html#POD :
2043 // In general, a type is considered a POD for the purposes of
2044 // layout if it is a POD type (in the sense of ISO C++
2045 // [basic.types]). However, a POD-struct or POD-union (in the
2046 // sense of ISO C++ [class]) with a bitfield member whose
2047 // declared width is wider than the declared type of the
2048 // bitfield is not a POD for the purpose of layout. Similarly,
2049 // an array type is not a POD for the purpose of layout if the
2050 // element type of the array is not a POD for the purpose of
2053 // Where references to the ISO C++ are made in this paragraph,
2054 // the Technical Corrigendum 1 version of the standard is
2058 case TargetCXXABI::UseTailPaddingUnlessPOD11:
2059 // This is equivalent to RD->getTypeForDecl().isCXX11PODType(),
2060 // but with a lot of abstraction penalty stripped off. This does
2061 // assume that these properties are set correctly even in C++98
2062 // mode; fortunately, that is true because we want to assign
2063 // consistently semantics to the type-traits intrinsics (or at
2064 // least as many of them as possible).
2065 return RD->isTrivial() && RD->isStandardLayout();
2068 llvm_unreachable("bad tail-padding use kind");
2071 static bool isMsLayout(const RecordDecl* D) {
2072 return D->getASTContext().getTargetInfo().getCXXABI().isMicrosoft();
2075 // This section contains an implementation of struct layout that is, up to the
2076 // included tests, compatible with cl.exe (2013). The layout produced is
2077 // significantly different than those produced by the Itanium ABI. Here we note
2078 // the most important differences.
2080 // * The alignment of bitfields in unions is ignored when computing the
2081 // alignment of the union.
2082 // * The existence of zero-width bitfield that occurs after anything other than
2083 // a non-zero length bitfield is ignored.
2084 // * There is no explicit primary base for the purposes of layout. All bases
2085 // with vfptrs are laid out first, followed by all bases without vfptrs.
2086 // * The Itanium equivalent vtable pointers are split into a vfptr (virtual
2087 // function pointer) and a vbptr (virtual base pointer). They can each be
2088 // shared with a, non-virtual bases. These bases need not be the same. vfptrs
2089 // always occur at offset 0. vbptrs can occur at an arbitrary offset and are
2090 // placed after the lexiographically last non-virtual base. This placement
2091 // is always before fields but can be in the middle of the non-virtual bases
2092 // due to the two-pass layout scheme for non-virtual-bases.
2093 // * Virtual bases sometimes require a 'vtordisp' field that is laid out before
2094 // the virtual base and is used in conjunction with virtual overrides during
2095 // construction and destruction. This is always a 4 byte value and is used as
2096 // an alternative to constructor vtables.
2097 // * vtordisps are allocated in a block of memory with size and alignment equal
2098 // to the alignment of the completed structure (before applying __declspec(
2099 // align())). The vtordisp always occur at the end of the allocation block,
2100 // immediately prior to the virtual base.
2101 // * vfptrs are injected after all bases and fields have been laid out. In
2102 // order to guarantee proper alignment of all fields, the vfptr injection
2103 // pushes all bases and fields back by the alignment imposed by those bases
2104 // and fields. This can potentially add a significant amount of padding.
2105 // vfptrs are always injected at offset 0.
2106 // * vbptrs are injected after all bases and fields have been laid out. In
2107 // order to guarantee proper alignment of all fields, the vfptr injection
2108 // pushes all bases and fields back by the alignment imposed by those bases
2109 // and fields. This can potentially add a significant amount of padding.
2110 // vbptrs are injected immediately after the last non-virtual base as
2111 // lexiographically ordered in the code. If this site isn't pointer aligned
2112 // the vbptr is placed at the next properly aligned location. Enough padding
2113 // is added to guarantee a fit.
2114 // * The last zero sized non-virtual base can be placed at the end of the
2115 // struct (potentially aliasing another object), or may alias with the first
2116 // field, even if they are of the same type.
2117 // * The last zero size virtual base may be placed at the end of the struct
2118 // potentially aliasing another object.
2119 // * The ABI attempts to avoid aliasing of zero sized bases by adding padding
2120 // between bases or vbases with specific properties. The criteria for
2121 // additional padding between two bases is that the first base is zero sized
2122 // or ends with a zero sized subobject and the second base is zero sized or
2123 // trails with a zero sized base or field (sharing of vfptrs can reorder the
2124 // layout of the so the leading base is not always the first one declared).
2125 // This rule does take into account fields that are not records, so padding
2126 // will occur even if the last field is, e.g. an int. The padding added for
2127 // bases is 1 byte. The padding added between vbases depends on the alignment
2128 // of the object but is at least 4 bytes (in both 32 and 64 bit modes).
2129 // * There is no concept of non-virtual alignment, non-virtual alignment and
2130 // alignment are always identical.
2131 // * There is a distinction between alignment and required alignment.
2132 // __declspec(align) changes the required alignment of a struct. This
2133 // alignment is _always_ obeyed, even in the presence of #pragma pack. A
2134 // record inherits required alignment from all of its fields and bases.
2135 // * __declspec(align) on bitfields has the effect of changing the bitfield's
2136 // alignment instead of its required alignment. This is the only known way
2137 // to make the alignment of a struct bigger than 8. Interestingly enough
2138 // this alignment is also immune to the effects of #pragma pack and can be
2139 // used to create structures with large alignment under #pragma pack.
2140 // However, because it does not impact required alignment, such a structure,
2141 // when used as a field or base, will not be aligned if #pragma pack is
2142 // still active at the time of use.
2144 // Known incompatibilities:
2145 // * all: #pragma pack between fields in a record
2146 // * 2010 and back: If the last field in a record is a bitfield, every object
2147 // laid out after the record will have extra padding inserted before it. The
2148 // extra padding will have size equal to the size of the storage class of the
2149 // bitfield. 0 sized bitfields don't exhibit this behavior and the extra
2150 // padding can be avoided by adding a 0 sized bitfield after the non-zero-
2152 // * 2012 and back: In 64-bit mode, if the alignment of a record is 16 or
2153 // greater due to __declspec(align()) then a second layout phase occurs after
2154 // The locations of the vf and vb pointers are known. This layout phase
2155 // suffers from the "last field is a bitfield" bug in 2010 and results in
2156 // _every_ field getting padding put in front of it, potentially including the
2157 // vfptr, leaving the vfprt at a non-zero location which results in a fault if
2158 // anything tries to read the vftbl. The second layout phase also treats
2159 // bitfields as separate entities and gives them each storage rather than
2160 // packing them. Additionally, because this phase appears to perform a
2161 // (an unstable) sort on the members before laying them out and because merged
2162 // bitfields have the same address, the bitfields end up in whatever order
2163 // the sort left them in, a behavior we could never hope to replicate.
2166 struct MicrosoftRecordLayoutBuilder {
2167 struct ElementInfo {
2169 CharUnits Alignment;
2171 typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsetsMapTy;
2172 MicrosoftRecordLayoutBuilder(const ASTContext &Context) : Context(Context) {}
2174 MicrosoftRecordLayoutBuilder(const MicrosoftRecordLayoutBuilder &) = delete;
2175 void operator=(const MicrosoftRecordLayoutBuilder &) = delete;
2177 void layout(const RecordDecl *RD);
2178 void cxxLayout(const CXXRecordDecl *RD);
2179 /// \brief Initializes size and alignment and honors some flags.
2180 void initializeLayout(const RecordDecl *RD);
2181 /// \brief Initialized C++ layout, compute alignment and virtual alignment and
2182 /// existence of vfptrs and vbptrs. Alignment is needed before the vfptr is
2184 void initializeCXXLayout(const CXXRecordDecl *RD);
2185 void layoutNonVirtualBases(const CXXRecordDecl *RD);
2186 void layoutNonVirtualBase(const CXXRecordDecl *BaseDecl,
2187 const ASTRecordLayout &BaseLayout,
2188 const ASTRecordLayout *&PreviousBaseLayout);
2189 void injectVFPtr(const CXXRecordDecl *RD);
2190 void injectVBPtr(const CXXRecordDecl *RD);
2191 /// \brief Lays out the fields of the record. Also rounds size up to
2193 void layoutFields(const RecordDecl *RD);
2194 void layoutField(const FieldDecl *FD);
2195 void layoutBitField(const FieldDecl *FD);
2196 /// \brief Lays out a single zero-width bit-field in the record and handles
2197 /// special cases associated with zero-width bit-fields.
2198 void layoutZeroWidthBitField(const FieldDecl *FD);
2199 void layoutVirtualBases(const CXXRecordDecl *RD);
2200 void finalizeLayout(const RecordDecl *RD);
2201 /// \brief Gets the size and alignment of a base taking pragma pack and
2202 /// __declspec(align) into account.
2203 ElementInfo getAdjustedElementInfo(const ASTRecordLayout &Layout);
2204 /// \brief Gets the size and alignment of a field taking pragma pack and
2205 /// __declspec(align) into account. It also updates RequiredAlignment as a
2206 /// side effect because it is most convenient to do so here.
2207 ElementInfo getAdjustedElementInfo(const FieldDecl *FD);
2208 /// \brief Places a field at an offset in CharUnits.
2209 void placeFieldAtOffset(CharUnits FieldOffset) {
2210 FieldOffsets.push_back(Context.toBits(FieldOffset));
2212 /// \brief Places a bitfield at a bit offset.
2213 void placeFieldAtBitOffset(uint64_t FieldOffset) {
2214 FieldOffsets.push_back(FieldOffset);
2216 /// \brief Compute the set of virtual bases for which vtordisps are required.
2217 void computeVtorDispSet(
2218 llvm::SmallPtrSetImpl<const CXXRecordDecl *> &HasVtorDispSet,
2219 const CXXRecordDecl *RD) const;
2220 const ASTContext &Context;
2221 /// \brief The size of the record being laid out.
2223 /// \brief The non-virtual size of the record layout.
2224 CharUnits NonVirtualSize;
2225 /// \brief The data size of the record layout.
2227 /// \brief The current alignment of the record layout.
2228 CharUnits Alignment;
2229 /// \brief The maximum allowed field alignment. This is set by #pragma pack.
2230 CharUnits MaxFieldAlignment;
2231 /// \brief The alignment that this record must obey. This is imposed by
2232 /// __declspec(align()) on the record itself or one of its fields or bases.
2233 CharUnits RequiredAlignment;
2234 /// \brief The size of the allocation of the currently active bitfield.
2235 /// This value isn't meaningful unless LastFieldIsNonZeroWidthBitfield
2237 CharUnits CurrentBitfieldSize;
2238 /// \brief Offset to the virtual base table pointer (if one exists).
2239 CharUnits VBPtrOffset;
2240 /// \brief Minimum record size possible.
2241 CharUnits MinEmptyStructSize;
2242 /// \brief The size and alignment info of a pointer.
2243 ElementInfo PointerInfo;
2244 /// \brief The primary base class (if one exists).
2245 const CXXRecordDecl *PrimaryBase;
2246 /// \brief The class we share our vb-pointer with.
2247 const CXXRecordDecl *SharedVBPtrBase;
2248 /// \brief The collection of field offsets.
2249 SmallVector<uint64_t, 16> FieldOffsets;
2250 /// \brief Base classes and their offsets in the record.
2251 BaseOffsetsMapTy Bases;
2252 /// \brief virtual base classes and their offsets in the record.
2253 ASTRecordLayout::VBaseOffsetsMapTy VBases;
2254 /// \brief The number of remaining bits in our last bitfield allocation.
2255 /// This value isn't meaningful unless LastFieldIsNonZeroWidthBitfield is
2257 unsigned RemainingBitsInField;
2259 /// \brief True if the last field laid out was a bitfield and was not 0
2261 bool LastFieldIsNonZeroWidthBitfield : 1;
2262 /// \brief True if the class has its own vftable pointer.
2263 bool HasOwnVFPtr : 1;
2264 /// \brief True if the class has a vbtable pointer.
2266 /// \brief True if the last sub-object within the type is zero sized or the
2267 /// object itself is zero sized. This *does not* count members that are not
2268 /// records. Only used for MS-ABI.
2269 bool EndsWithZeroSizedObject : 1;
2270 /// \brief True if this class is zero sized or first base is zero sized or
2271 /// has this property. Only used for MS-ABI.
2272 bool LeadsWithZeroSizedBase : 1;
2274 /// \brief True if the external AST source provided a layout for this record.
2275 bool UseExternalLayout : 1;
2277 /// \brief The layout provided by the external AST source. Only active if
2278 /// UseExternalLayout is true.
2279 ExternalLayout External;
2283 MicrosoftRecordLayoutBuilder::ElementInfo
2284 MicrosoftRecordLayoutBuilder::getAdjustedElementInfo(
2285 const ASTRecordLayout &Layout) {
2287 Info.Alignment = Layout.getAlignment();
2288 // Respect pragma pack.
2289 if (!MaxFieldAlignment.isZero())
2290 Info.Alignment = std::min(Info.Alignment, MaxFieldAlignment);
2291 // Track zero-sized subobjects here where it's already available.
2292 EndsWithZeroSizedObject = Layout.hasZeroSizedSubObject();
2293 // Respect required alignment, this is necessary because we may have adjusted
2294 // the alignment in the case of pragam pack. Note that the required alignment
2295 // doesn't actually apply to the struct alignment at this point.
2296 Alignment = std::max(Alignment, Info.Alignment);
2297 RequiredAlignment = std::max(RequiredAlignment, Layout.getRequiredAlignment());
2298 Info.Alignment = std::max(Info.Alignment, Layout.getRequiredAlignment());
2299 Info.Size = Layout.getNonVirtualSize();
2303 MicrosoftRecordLayoutBuilder::ElementInfo
2304 MicrosoftRecordLayoutBuilder::getAdjustedElementInfo(
2305 const FieldDecl *FD) {
2306 // Get the alignment of the field type's natural alignment, ignore any
2307 // alignment attributes.
2309 std::tie(Info.Size, Info.Alignment) =
2310 Context.getTypeInfoInChars(FD->getType()->getUnqualifiedDesugaredType());
2311 // Respect align attributes on the field.
2312 CharUnits FieldRequiredAlignment =
2313 Context.toCharUnitsFromBits(FD->getMaxAlignment());
2314 // Respect align attributes on the type.
2315 if (Context.isAlignmentRequired(FD->getType()))
2316 FieldRequiredAlignment = std::max(
2317 Context.getTypeAlignInChars(FD->getType()), FieldRequiredAlignment);
2318 // Respect attributes applied to subobjects of the field.
2319 if (FD->isBitField())
2320 // For some reason __declspec align impacts alignment rather than required
2321 // alignment when it is applied to bitfields.
2322 Info.Alignment = std::max(Info.Alignment, FieldRequiredAlignment);
2325 FD->getType()->getBaseElementTypeUnsafe()->getAs<RecordType>()) {
2326 auto const &Layout = Context.getASTRecordLayout(RT->getDecl());
2327 EndsWithZeroSizedObject = Layout.hasZeroSizedSubObject();
2328 FieldRequiredAlignment = std::max(FieldRequiredAlignment,
2329 Layout.getRequiredAlignment());
2331 // Capture required alignment as a side-effect.
2332 RequiredAlignment = std::max(RequiredAlignment, FieldRequiredAlignment);
2334 // Respect pragma pack, attribute pack and declspec align
2335 if (!MaxFieldAlignment.isZero())
2336 Info.Alignment = std::min(Info.Alignment, MaxFieldAlignment);
2337 if (FD->hasAttr<PackedAttr>())
2338 Info.Alignment = CharUnits::One();
2339 Info.Alignment = std::max(Info.Alignment, FieldRequiredAlignment);
2343 void MicrosoftRecordLayoutBuilder::layout(const RecordDecl *RD) {
2344 // For C record layout, zero-sized records always have size 4.
2345 MinEmptyStructSize = CharUnits::fromQuantity(4);
2346 initializeLayout(RD);
2348 DataSize = Size = Size.RoundUpToAlignment(Alignment);
2349 RequiredAlignment = std::max(
2350 RequiredAlignment, Context.toCharUnitsFromBits(RD->getMaxAlignment()));
2354 void MicrosoftRecordLayoutBuilder::cxxLayout(const CXXRecordDecl *RD) {
2355 // The C++ standard says that empty structs have size 1.
2356 MinEmptyStructSize = CharUnits::One();
2357 initializeLayout(RD);
2358 initializeCXXLayout(RD);
2359 layoutNonVirtualBases(RD);
2363 if (HasOwnVFPtr || (HasVBPtr && !SharedVBPtrBase))
2364 Alignment = std::max(Alignment, PointerInfo.Alignment);
2365 auto RoundingAlignment = Alignment;
2366 if (!MaxFieldAlignment.isZero())
2367 RoundingAlignment = std::min(RoundingAlignment, MaxFieldAlignment);
2368 NonVirtualSize = Size = Size.RoundUpToAlignment(RoundingAlignment);
2369 RequiredAlignment = std::max(
2370 RequiredAlignment, Context.toCharUnitsFromBits(RD->getMaxAlignment()));
2371 layoutVirtualBases(RD);
2375 void MicrosoftRecordLayoutBuilder::initializeLayout(const RecordDecl *RD) {
2376 IsUnion = RD->isUnion();
2377 Size = CharUnits::Zero();
2378 Alignment = CharUnits::One();
2379 // In 64-bit mode we always perform an alignment step after laying out vbases.
2380 // In 32-bit mode we do not. The check to see if we need to perform alignment
2381 // checks the RequiredAlignment field and performs alignment if it isn't 0.
2382 RequiredAlignment = Context.getTargetInfo().getTriple().isArch64Bit()
2384 : CharUnits::Zero();
2385 // Compute the maximum field alignment.
2386 MaxFieldAlignment = CharUnits::Zero();
2387 // Honor the default struct packing maximum alignment flag.
2388 if (unsigned DefaultMaxFieldAlignment = Context.getLangOpts().PackStruct)
2389 MaxFieldAlignment = CharUnits::fromQuantity(DefaultMaxFieldAlignment);
2390 // Honor the packing attribute. The MS-ABI ignores pragma pack if its larger
2391 // than the pointer size.
2392 if (const MaxFieldAlignmentAttr *MFAA = RD->getAttr<MaxFieldAlignmentAttr>()){
2393 unsigned PackedAlignment = MFAA->getAlignment();
2394 if (PackedAlignment <= Context.getTargetInfo().getPointerWidth(0))
2395 MaxFieldAlignment = Context.toCharUnitsFromBits(PackedAlignment);
2397 // Packed attribute forces max field alignment to be 1.
2398 if (RD->hasAttr<PackedAttr>())
2399 MaxFieldAlignment = CharUnits::One();
2401 // Try to respect the external layout if present.
2402 UseExternalLayout = false;
2403 if (ExternalASTSource *Source = Context.getExternalSource())
2404 UseExternalLayout = Source->layoutRecordType(
2405 RD, External.Size, External.Align, External.FieldOffsets,
2406 External.BaseOffsets, External.VirtualBaseOffsets);
2410 MicrosoftRecordLayoutBuilder::initializeCXXLayout(const CXXRecordDecl *RD) {
2411 EndsWithZeroSizedObject = false;
2412 LeadsWithZeroSizedBase = false;
2413 HasOwnVFPtr = false;
2415 PrimaryBase = nullptr;
2416 SharedVBPtrBase = nullptr;
2417 // Calculate pointer size and alignment. These are used for vfptr and vbprt
2420 Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
2421 PointerInfo.Alignment =
2422 Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerAlign(0));
2423 // Respect pragma pack.
2424 if (!MaxFieldAlignment.isZero())
2425 PointerInfo.Alignment = std::min(PointerInfo.Alignment, MaxFieldAlignment);
2429 MicrosoftRecordLayoutBuilder::layoutNonVirtualBases(const CXXRecordDecl *RD) {
2430 // The MS-ABI lays out all bases that contain leading vfptrs before it lays
2431 // out any bases that do not contain vfptrs. We implement this as two passes
2432 // over the bases. This approach guarantees that the primary base is laid out
2433 // first. We use these passes to calculate some additional aggregated
2434 // information about the bases, such as reqruied alignment and the presence of
2435 // zero sized members.
2436 const ASTRecordLayout *PreviousBaseLayout = nullptr;
2437 // Iterate through the bases and lay out the non-virtual ones.
2438 for (const CXXBaseSpecifier &Base : RD->bases()) {
2439 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2440 const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2441 // Mark and skip virtual bases.
2442 if (Base.isVirtual()) {
2446 // Check fo a base to share a VBPtr with.
2447 if (!SharedVBPtrBase && BaseLayout.hasVBPtr()) {
2448 SharedVBPtrBase = BaseDecl;
2451 // Only lay out bases with extendable VFPtrs on the first pass.
2452 if (!BaseLayout.hasExtendableVFPtr())
2454 // If we don't have a primary base, this one qualifies.
2456 PrimaryBase = BaseDecl;
2457 LeadsWithZeroSizedBase = BaseLayout.leadsWithZeroSizedBase();
2459 // Lay out the base.
2460 layoutNonVirtualBase(BaseDecl, BaseLayout, PreviousBaseLayout);
2462 // Figure out if we need a fresh VFPtr for this class.
2463 if (!PrimaryBase && RD->isDynamicClass())
2464 for (CXXRecordDecl::method_iterator i = RD->method_begin(),
2465 e = RD->method_end();
2466 !HasOwnVFPtr && i != e; ++i)
2467 HasOwnVFPtr = i->isVirtual() && i->size_overridden_methods() == 0;
2468 // If we don't have a primary base then we have a leading object that could
2469 // itself lead with a zero-sized object, something we track.
2470 bool CheckLeadingLayout = !PrimaryBase;
2471 // Iterate through the bases and lay out the non-virtual ones.
2472 for (const CXXBaseSpecifier &Base : RD->bases()) {
2473 if (Base.isVirtual())
2475 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2476 const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2477 // Only lay out bases without extendable VFPtrs on the second pass.
2478 if (BaseLayout.hasExtendableVFPtr()) {
2479 VBPtrOffset = Bases[BaseDecl] + BaseLayout.getNonVirtualSize();
2482 // If this is the first layout, check to see if it leads with a zero sized
2483 // object. If it does, so do we.
2484 if (CheckLeadingLayout) {
2485 CheckLeadingLayout = false;
2486 LeadsWithZeroSizedBase = BaseLayout.leadsWithZeroSizedBase();
2488 // Lay out the base.
2489 layoutNonVirtualBase(BaseDecl, BaseLayout, PreviousBaseLayout);
2490 VBPtrOffset = Bases[BaseDecl] + BaseLayout.getNonVirtualSize();
2492 // Set our VBPtroffset if we know it at this point.
2494 VBPtrOffset = CharUnits::fromQuantity(-1);
2495 else if (SharedVBPtrBase) {
2496 const ASTRecordLayout &Layout = Context.getASTRecordLayout(SharedVBPtrBase);
2497 VBPtrOffset = Bases[SharedVBPtrBase] + Layout.getVBPtrOffset();
2501 void MicrosoftRecordLayoutBuilder::layoutNonVirtualBase(
2502 const CXXRecordDecl *BaseDecl,
2503 const ASTRecordLayout &BaseLayout,
2504 const ASTRecordLayout *&PreviousBaseLayout) {
2505 // Insert padding between two bases if the left first one is zero sized or
2506 // contains a zero sized subobject and the right is zero sized or one leads
2507 // with a zero sized base.
2508 if (PreviousBaseLayout && PreviousBaseLayout->hasZeroSizedSubObject() &&
2509 BaseLayout.leadsWithZeroSizedBase())
2511 ElementInfo Info = getAdjustedElementInfo(BaseLayout);
2512 CharUnits BaseOffset;
2514 // Respect the external AST source base offset, if present.
2515 bool FoundBase = false;
2516 if (UseExternalLayout) {
2517 FoundBase = External.getExternalNVBaseOffset(BaseDecl, BaseOffset);
2519 assert(BaseOffset >= Size && "base offset already allocated");
2523 BaseOffset = Size.RoundUpToAlignment(Info.Alignment);
2524 Bases.insert(std::make_pair(BaseDecl, BaseOffset));
2525 Size = BaseOffset + BaseLayout.getNonVirtualSize();
2526 PreviousBaseLayout = &BaseLayout;
2529 void MicrosoftRecordLayoutBuilder::layoutFields(const RecordDecl *RD) {
2530 LastFieldIsNonZeroWidthBitfield = false;
2531 for (const FieldDecl *Field : RD->fields())
2535 void MicrosoftRecordLayoutBuilder::layoutField(const FieldDecl *FD) {
2536 if (FD->isBitField()) {
2540 LastFieldIsNonZeroWidthBitfield = false;
2541 ElementInfo Info = getAdjustedElementInfo(FD);
2542 Alignment = std::max(Alignment, Info.Alignment);
2544 placeFieldAtOffset(CharUnits::Zero());
2545 Size = std::max(Size, Info.Size);
2547 CharUnits FieldOffset;
2548 if (UseExternalLayout) {
2550 Context.toCharUnitsFromBits(External.getExternalFieldOffset(FD));
2551 assert(FieldOffset >= Size && "field offset already allocated");
2553 FieldOffset = Size.RoundUpToAlignment(Info.Alignment);
2555 placeFieldAtOffset(FieldOffset);
2556 Size = FieldOffset + Info.Size;
2560 void MicrosoftRecordLayoutBuilder::layoutBitField(const FieldDecl *FD) {
2561 unsigned Width = FD->getBitWidthValue(Context);
2563 layoutZeroWidthBitField(FD);
2566 ElementInfo Info = getAdjustedElementInfo(FD);
2567 // Clamp the bitfield to a containable size for the sake of being able
2568 // to lay them out. Sema will throw an error.
2569 if (Width > Context.toBits(Info.Size))
2570 Width = Context.toBits(Info.Size);
2571 // Check to see if this bitfield fits into an existing allocation. Note:
2572 // MSVC refuses to pack bitfields of formal types with different sizes
2573 // into the same allocation.
2574 if (!IsUnion && LastFieldIsNonZeroWidthBitfield &&
2575 CurrentBitfieldSize == Info.Size && Width <= RemainingBitsInField) {
2576 placeFieldAtBitOffset(Context.toBits(Size) - RemainingBitsInField);
2577 RemainingBitsInField -= Width;
2580 LastFieldIsNonZeroWidthBitfield = true;
2581 CurrentBitfieldSize = Info.Size;
2583 placeFieldAtOffset(CharUnits::Zero());
2584 Size = std::max(Size, Info.Size);
2585 // TODO: Add a Sema warning that MS ignores bitfield alignment in unions.
2587 // Allocate a new block of memory and place the bitfield in it.
2588 CharUnits FieldOffset = Size.RoundUpToAlignment(Info.Alignment);
2589 placeFieldAtOffset(FieldOffset);
2590 Size = FieldOffset + Info.Size;
2591 Alignment = std::max(Alignment, Info.Alignment);
2592 RemainingBitsInField = Context.toBits(Info.Size) - Width;
2597 MicrosoftRecordLayoutBuilder::layoutZeroWidthBitField(const FieldDecl *FD) {
2598 // Zero-width bitfields are ignored unless they follow a non-zero-width
2600 if (!LastFieldIsNonZeroWidthBitfield) {
2601 placeFieldAtOffset(IsUnion ? CharUnits::Zero() : Size);
2602 // TODO: Add a Sema warning that MS ignores alignment for zero
2603 // sized bitfields that occur after zero-size bitfields or non-bitfields.
2606 LastFieldIsNonZeroWidthBitfield = false;
2607 ElementInfo Info = getAdjustedElementInfo(FD);
2609 placeFieldAtOffset(CharUnits::Zero());
2610 Size = std::max(Size, Info.Size);
2611 // TODO: Add a Sema warning that MS ignores bitfield alignment in unions.
2613 // Round up the current record size to the field's alignment boundary.
2614 CharUnits FieldOffset = Size.RoundUpToAlignment(Info.Alignment);
2615 placeFieldAtOffset(FieldOffset);
2617 Alignment = std::max(Alignment, Info.Alignment);
2621 void MicrosoftRecordLayoutBuilder::injectVBPtr(const CXXRecordDecl *RD) {
2622 if (!HasVBPtr || SharedVBPtrBase)
2624 // Inject the VBPointer at the injection site.
2625 CharUnits InjectionSite = VBPtrOffset;
2626 // But before we do, make sure it's properly aligned.
2627 VBPtrOffset = VBPtrOffset.RoundUpToAlignment(PointerInfo.Alignment);
2628 // Shift everything after the vbptr down, unless we're using an external
2630 if (UseExternalLayout)
2632 // Determine where the first field should be laid out after the vbptr.
2633 CharUnits FieldStart = VBPtrOffset + PointerInfo.Size;
2634 // Make sure that the amount we push the fields back by is a multiple of the
2636 CharUnits Offset = (FieldStart - InjectionSite).RoundUpToAlignment(
2637 std::max(RequiredAlignment, Alignment));
2639 for (uint64_t &FieldOffset : FieldOffsets)
2640 FieldOffset += Context.toBits(Offset);
2641 for (BaseOffsetsMapTy::value_type &Base : Bases)
2642 if (Base.second >= InjectionSite)
2643 Base.second += Offset;
2646 void MicrosoftRecordLayoutBuilder::injectVFPtr(const CXXRecordDecl *RD) {
2649 // Make sure that the amount we push the struct back by is a multiple of the
2651 CharUnits Offset = PointerInfo.Size.RoundUpToAlignment(
2652 std::max(RequiredAlignment, Alignment));
2653 // Increase the size of the object and push back all fields, the vbptr and all
2654 // bases by the offset amount.
2656 for (uint64_t &FieldOffset : FieldOffsets)
2657 FieldOffset += Context.toBits(Offset);
2659 VBPtrOffset += Offset;
2660 for (BaseOffsetsMapTy::value_type &Base : Bases)
2661 Base.second += Offset;
2664 void MicrosoftRecordLayoutBuilder::layoutVirtualBases(const CXXRecordDecl *RD) {
2667 // Vtordisps are always 4 bytes (even in 64-bit mode)
2668 CharUnits VtorDispSize = CharUnits::fromQuantity(4);
2669 CharUnits VtorDispAlignment = VtorDispSize;
2670 // vtordisps respect pragma pack.
2671 if (!MaxFieldAlignment.isZero())
2672 VtorDispAlignment = std::min(VtorDispAlignment, MaxFieldAlignment);
2673 // The alignment of the vtordisp is at least the required alignment of the
2674 // entire record. This requirement may be present to support vtordisp
2676 for (const CXXBaseSpecifier &VBase : RD->vbases()) {
2677 const CXXRecordDecl *BaseDecl = VBase.getType()->getAsCXXRecordDecl();
2678 const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2680 std::max(RequiredAlignment, BaseLayout.getRequiredAlignment());
2682 VtorDispAlignment = std::max(VtorDispAlignment, RequiredAlignment);
2683 // Compute the vtordisp set.
2684 llvm::SmallPtrSet<const CXXRecordDecl *, 2> HasVtorDispSet;
2685 computeVtorDispSet(HasVtorDispSet, RD);
2686 // Iterate through the virtual bases and lay them out.
2687 const ASTRecordLayout *PreviousBaseLayout = nullptr;
2688 for (const CXXBaseSpecifier &VBase : RD->vbases()) {
2689 const CXXRecordDecl *BaseDecl = VBase.getType()->getAsCXXRecordDecl();
2690 const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
2691 bool HasVtordisp = HasVtorDispSet.count(BaseDecl) > 0;
2692 // Insert padding between two bases if the left first one is zero sized or
2693 // contains a zero sized subobject and the right is zero sized or one leads
2694 // with a zero sized base. The padding between virtual bases is 4
2695 // bytes (in both 32 and 64 bits modes) and always involves rounding up to
2696 // the required alignment, we don't know why.
2697 if ((PreviousBaseLayout && PreviousBaseLayout->hasZeroSizedSubObject() &&
2698 BaseLayout.leadsWithZeroSizedBase()) || HasVtordisp) {
2699 Size = Size.RoundUpToAlignment(VtorDispAlignment) + VtorDispSize;
2700 Alignment = std::max(VtorDispAlignment, Alignment);
2702 // Insert the virtual base.
2703 ElementInfo Info = getAdjustedElementInfo(BaseLayout);
2704 CharUnits BaseOffset;
2706 // Respect the external AST source base offset, if present.
2707 bool FoundBase = false;
2708 if (UseExternalLayout) {
2709 FoundBase = External.getExternalVBaseOffset(BaseDecl, BaseOffset);
2711 assert(BaseOffset >= Size && "base offset already allocated");
2714 BaseOffset = Size.RoundUpToAlignment(Info.Alignment);
2716 VBases.insert(std::make_pair(BaseDecl,
2717 ASTRecordLayout::VBaseInfo(BaseOffset, HasVtordisp)));
2718 Size = BaseOffset + BaseLayout.getNonVirtualSize();
2719 PreviousBaseLayout = &BaseLayout;
2723 void MicrosoftRecordLayoutBuilder::finalizeLayout(const RecordDecl *RD) {
2724 // Respect required alignment. Note that in 32-bit mode Required alignment
2725 // may be 0 and cause size not to be updated.
2727 if (!RequiredAlignment.isZero()) {
2728 Alignment = std::max(Alignment, RequiredAlignment);
2729 auto RoundingAlignment = Alignment;
2730 if (!MaxFieldAlignment.isZero())
2731 RoundingAlignment = std::min(RoundingAlignment, MaxFieldAlignment);
2732 RoundingAlignment = std::max(RoundingAlignment, RequiredAlignment);
2733 Size = Size.RoundUpToAlignment(RoundingAlignment);
2735 if (Size.isZero()) {
2736 EndsWithZeroSizedObject = true;
2737 LeadsWithZeroSizedBase = true;
2738 // Zero-sized structures have size equal to their alignment if a
2739 // __declspec(align) came into play.
2740 if (RequiredAlignment >= MinEmptyStructSize)
2743 Size = MinEmptyStructSize;
2746 if (UseExternalLayout) {
2747 Size = Context.toCharUnitsFromBits(External.Size);
2749 Alignment = Context.toCharUnitsFromBits(External.Align);
2753 // Recursively walks the non-virtual bases of a class and determines if any of
2754 // them are in the bases with overridden methods set.
2756 RequiresVtordisp(const llvm::SmallPtrSetImpl<const CXXRecordDecl *> &
2757 BasesWithOverriddenMethods,
2758 const CXXRecordDecl *RD) {
2759 if (BasesWithOverriddenMethods.count(RD))
2761 // If any of a virtual bases non-virtual bases (recursively) requires a
2762 // vtordisp than so does this virtual base.
2763 for (const CXXBaseSpecifier &Base : RD->bases())
2764 if (!Base.isVirtual() &&
2765 RequiresVtordisp(BasesWithOverriddenMethods,
2766 Base.getType()->getAsCXXRecordDecl()))
2771 void MicrosoftRecordLayoutBuilder::computeVtorDispSet(
2772 llvm::SmallPtrSetImpl<const CXXRecordDecl *> &HasVtordispSet,
2773 const CXXRecordDecl *RD) const {
2774 // /vd2 or #pragma vtordisp(2): Always use vtordisps for virtual bases with
2776 if (RD->getMSVtorDispMode() == MSVtorDispAttr::ForVFTable) {
2777 for (const CXXBaseSpecifier &Base : RD->vbases()) {
2778 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2779 const ASTRecordLayout &Layout = Context.getASTRecordLayout(BaseDecl);
2780 if (Layout.hasExtendableVFPtr())
2781 HasVtordispSet.insert(BaseDecl);
2786 // If any of our bases need a vtordisp for this type, so do we. Check our
2787 // direct bases for vtordisp requirements.
2788 for (const CXXBaseSpecifier &Base : RD->bases()) {
2789 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2790 const ASTRecordLayout &Layout = Context.getASTRecordLayout(BaseDecl);
2791 for (const auto &bi : Layout.getVBaseOffsetsMap())
2792 if (bi.second.hasVtorDisp())
2793 HasVtordispSet.insert(bi.first);
2795 // We don't introduce any additional vtordisps if either:
2796 // * A user declared constructor or destructor aren't declared.
2797 // * #pragma vtordisp(0) or the /vd0 flag are in use.
2798 if ((!RD->hasUserDeclaredConstructor() && !RD->hasUserDeclaredDestructor()) ||
2799 RD->getMSVtorDispMode() == MSVtorDispAttr::Never)
2801 // /vd1 or #pragma vtordisp(1): Try to guess based on whether we think it's
2802 // possible for a partially constructed object with virtual base overrides to
2803 // escape a non-trivial constructor.
2804 assert(RD->getMSVtorDispMode() == MSVtorDispAttr::ForVBaseOverride);
2805 // Compute a set of base classes which define methods we override. A virtual
2806 // base in this set will require a vtordisp. A virtual base that transitively
2807 // contains one of these bases as a non-virtual base will also require a
2809 llvm::SmallPtrSet<const CXXMethodDecl *, 8> Work;
2810 llvm::SmallPtrSet<const CXXRecordDecl *, 2> BasesWithOverriddenMethods;
2811 // Seed the working set with our non-destructor, non-pure virtual methods.
2812 for (const CXXMethodDecl *MD : RD->methods())
2813 if (MD->isVirtual() && !isa<CXXDestructorDecl>(MD) && !MD->isPure())
2815 while (!Work.empty()) {
2816 const CXXMethodDecl *MD = *Work.begin();
2817 CXXMethodDecl::method_iterator i = MD->begin_overridden_methods(),
2818 e = MD->end_overridden_methods();
2819 // If a virtual method has no-overrides it lives in its parent's vtable.
2821 BasesWithOverriddenMethods.insert(MD->getParent());
2824 // We've finished processing this element, remove it from the working set.
2827 // For each of our virtual bases, check if it is in the set of overridden
2828 // bases or if it transitively contains a non-virtual base that is.
2829 for (const CXXBaseSpecifier &Base : RD->vbases()) {
2830 const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
2831 if (!HasVtordispSet.count(BaseDecl) &&
2832 RequiresVtordisp(BasesWithOverriddenMethods, BaseDecl))
2833 HasVtordispSet.insert(BaseDecl);
2837 /// \brief Get or compute information about the layout of the specified record
2838 /// (struct/union/class), which indicates its size and field position
2840 const ASTRecordLayout *
2841 ASTContext::BuildMicrosoftASTRecordLayout(const RecordDecl *D) const {
2842 MicrosoftRecordLayoutBuilder Builder(*this);
2843 if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D)) {
2844 Builder.cxxLayout(RD);
2845 return new (*this) ASTRecordLayout(
2846 *this, Builder.Size, Builder.Alignment, Builder.RequiredAlignment,
2847 Builder.HasOwnVFPtr,
2848 Builder.HasOwnVFPtr || Builder.PrimaryBase,
2849 Builder.VBPtrOffset, Builder.NonVirtualSize, Builder.FieldOffsets.data(),
2850 Builder.FieldOffsets.size(), Builder.NonVirtualSize,
2851 Builder.Alignment, CharUnits::Zero(), Builder.PrimaryBase,
2852 false, Builder.SharedVBPtrBase,
2853 Builder.EndsWithZeroSizedObject, Builder.LeadsWithZeroSizedBase,
2854 Builder.Bases, Builder.VBases);
2857 return new (*this) ASTRecordLayout(
2858 *this, Builder.Size, Builder.Alignment, Builder.RequiredAlignment,
2859 Builder.Size, Builder.FieldOffsets.data(), Builder.FieldOffsets.size());
2863 /// getASTRecordLayout - Get or compute information about the layout of the
2864 /// specified record (struct/union/class), which indicates its size and field
2865 /// position information.
2866 const ASTRecordLayout &
2867 ASTContext::getASTRecordLayout(const RecordDecl *D) const {
2868 // These asserts test different things. A record has a definition
2869 // as soon as we begin to parse the definition. That definition is
2870 // not a complete definition (which is what isDefinition() tests)
2871 // until we *finish* parsing the definition.
2873 if (D->hasExternalLexicalStorage() && !D->getDefinition())
2874 getExternalSource()->CompleteType(const_cast<RecordDecl*>(D));
2876 D = D->getDefinition();
2877 assert(D && "Cannot get layout of forward declarations!");
2878 assert(!D->isInvalidDecl() && "Cannot get layout of invalid decl!");
2879 assert(D->isCompleteDefinition() && "Cannot layout type before complete!");
2881 // Look up this layout, if already laid out, return what we have.
2882 // Note that we can't save a reference to the entry because this function
2884 const ASTRecordLayout *Entry = ASTRecordLayouts[D];
2885 if (Entry) return *Entry;
2887 const ASTRecordLayout *NewEntry = nullptr;
2889 if (isMsLayout(D)) {
2890 NewEntry = BuildMicrosoftASTRecordLayout(D);
2891 } else if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D)) {
2892 EmptySubobjectMap EmptySubobjects(*this, RD);
2893 RecordLayoutBuilder Builder(*this, &EmptySubobjects);
2896 // In certain situations, we are allowed to lay out objects in the
2897 // tail-padding of base classes. This is ABI-dependent.
2898 // FIXME: this should be stored in the record layout.
2899 bool skipTailPadding =
2900 mustSkipTailPadding(getTargetInfo().getCXXABI(), cast<CXXRecordDecl>(D));
2902 // FIXME: This should be done in FinalizeLayout.
2903 CharUnits DataSize =
2904 skipTailPadding ? Builder.getSize() : Builder.getDataSize();
2905 CharUnits NonVirtualSize =
2906 skipTailPadding ? DataSize : Builder.NonVirtualSize;
2908 new (*this) ASTRecordLayout(*this, Builder.getSize(),
2910 /*RequiredAlignment : used by MS-ABI)*/
2912 Builder.HasOwnVFPtr,
2913 RD->isDynamicClass(),
2914 CharUnits::fromQuantity(-1),
2916 Builder.FieldOffsets.data(),
2917 Builder.FieldOffsets.size(),
2919 Builder.NonVirtualAlignment,
2920 EmptySubobjects.SizeOfLargestEmptySubobject,
2921 Builder.PrimaryBase,
2922 Builder.PrimaryBaseIsVirtual,
2923 nullptr, false, false,
2924 Builder.Bases, Builder.VBases);
2926 RecordLayoutBuilder Builder(*this, /*EmptySubobjects=*/nullptr);
2930 new (*this) ASTRecordLayout(*this, Builder.getSize(),
2932 /*RequiredAlignment : used by MS-ABI)*/
2935 Builder.FieldOffsets.data(),
2936 Builder.FieldOffsets.size());
2939 ASTRecordLayouts[D] = NewEntry;
2941 if (getLangOpts().DumpRecordLayouts) {
2942 llvm::outs() << "\n*** Dumping AST Record Layout\n";
2943 DumpRecordLayout(D, llvm::outs(), getLangOpts().DumpRecordLayoutsSimple);
2949 const CXXMethodDecl *ASTContext::getCurrentKeyFunction(const CXXRecordDecl *RD) {
2950 if (!getTargetInfo().getCXXABI().hasKeyFunctions())
2953 assert(RD->getDefinition() && "Cannot get key function for forward decl!");
2954 RD = cast<CXXRecordDecl>(RD->getDefinition());
2957 // 1) computing the key function might trigger deserialization, which might
2958 // invalidate iterators into KeyFunctions
2959 // 2) 'get' on the LazyDeclPtr might also trigger deserialization and
2960 // invalidate the LazyDeclPtr within the map itself
2961 LazyDeclPtr Entry = KeyFunctions[RD];
2962 const Decl *Result =
2963 Entry ? Entry.get(getExternalSource()) : computeKeyFunction(*this, RD);
2965 // Store it back if it changed.
2966 if (Entry.isOffset() || Entry.isValid() != bool(Result))
2967 KeyFunctions[RD] = const_cast<Decl*>(Result);
2969 return cast_or_null<CXXMethodDecl>(Result);
2972 void ASTContext::setNonKeyFunction(const CXXMethodDecl *Method) {
2973 assert(Method == Method->getFirstDecl() &&
2974 "not working with method declaration from class definition");
2976 // Look up the cache entry. Since we're working with the first
2977 // declaration, its parent must be the class definition, which is
2978 // the correct key for the KeyFunctions hash.
2979 const auto &Map = KeyFunctions;
2980 auto I = Map.find(Method->getParent());
2982 // If it's not cached, there's nothing to do.
2983 if (I == Map.end()) return;
2985 // If it is cached, check whether it's the target method, and if so,
2986 // remove it from the cache. Note, the call to 'get' might invalidate
2987 // the iterator and the LazyDeclPtr object within the map.
2988 LazyDeclPtr Ptr = I->second;
2989 if (Ptr.get(getExternalSource()) == Method) {
2990 // FIXME: remember that we did this for module / chained PCH state?
2991 KeyFunctions.erase(Method->getParent());
2995 static uint64_t getFieldOffset(const ASTContext &C, const FieldDecl *FD) {
2996 const ASTRecordLayout &Layout = C.getASTRecordLayout(FD->getParent());
2997 return Layout.getFieldOffset(FD->getFieldIndex());
3000 uint64_t ASTContext::getFieldOffset(const ValueDecl *VD) const {
3001 uint64_t OffsetInBits;
3002 if (const FieldDecl *FD = dyn_cast<FieldDecl>(VD)) {
3003 OffsetInBits = ::getFieldOffset(*this, FD);
3005 const IndirectFieldDecl *IFD = cast<IndirectFieldDecl>(VD);
3008 for (const NamedDecl *ND : IFD->chain())
3009 OffsetInBits += ::getFieldOffset(*this, cast<FieldDecl>(ND));
3012 return OffsetInBits;
3015 /// getObjCLayout - Get or compute information about the layout of the
3016 /// given interface.
3018 /// \param Impl - If given, also include the layout of the interface's
3019 /// implementation. This may differ by including synthesized ivars.
3020 const ASTRecordLayout &
3021 ASTContext::getObjCLayout(const ObjCInterfaceDecl *D,
3022 const ObjCImplementationDecl *Impl) const {
3023 // Retrieve the definition
3024 if (D->hasExternalLexicalStorage() && !D->getDefinition())
3025 getExternalSource()->CompleteType(const_cast<ObjCInterfaceDecl*>(D));
3026 D = D->getDefinition();
3027 assert(D && D->isThisDeclarationADefinition() && "Invalid interface decl!");
3029 // Look up this layout, if already laid out, return what we have.
3030 const ObjCContainerDecl *Key =
3031 Impl ? (const ObjCContainerDecl*) Impl : (const ObjCContainerDecl*) D;
3032 if (const ASTRecordLayout *Entry = ObjCLayouts[Key])
3035 // Add in synthesized ivar count if laying out an implementation.
3037 unsigned SynthCount = CountNonClassIvars(D);
3038 // If there aren't any sythesized ivars then reuse the interface
3039 // entry. Note we can't cache this because we simply free all
3040 // entries later; however we shouldn't look up implementations
3042 if (SynthCount == 0)
3043 return getObjCLayout(D, nullptr);
3046 RecordLayoutBuilder Builder(*this, /*EmptySubobjects=*/nullptr);
3049 const ASTRecordLayout *NewEntry =
3050 new (*this) ASTRecordLayout(*this, Builder.getSize(),
3052 /*RequiredAlignment : used by MS-ABI)*/
3054 Builder.getDataSize(),
3055 Builder.FieldOffsets.data(),
3056 Builder.FieldOffsets.size());
3058 ObjCLayouts[Key] = NewEntry;
3063 static void PrintOffset(raw_ostream &OS,
3064 CharUnits Offset, unsigned IndentLevel) {
3065 OS << llvm::format("%4" PRId64 " | ", (int64_t)Offset.getQuantity());
3066 OS.indent(IndentLevel * 2);
3069 static void PrintIndentNoOffset(raw_ostream &OS, unsigned IndentLevel) {
3071 OS.indent(IndentLevel * 2);
3074 static void DumpCXXRecordLayout(raw_ostream &OS,
3075 const CXXRecordDecl *RD, const ASTContext &C,
3077 unsigned IndentLevel,
3078 const char* Description,
3079 bool IncludeVirtualBases) {
3080 const ASTRecordLayout &Layout = C.getASTRecordLayout(RD);
3082 PrintOffset(OS, Offset, IndentLevel);
3083 OS << C.getTypeDeclType(const_cast<CXXRecordDecl *>(RD)).getAsString();
3085 OS << ' ' << Description;
3092 const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
3093 bool HasOwnVFPtr = Layout.hasOwnVFPtr();
3094 bool HasOwnVBPtr = Layout.hasOwnVBPtr();
3097 if (RD->isDynamicClass() && !PrimaryBase && !isMsLayout(RD)) {
3098 PrintOffset(OS, Offset, IndentLevel);
3099 OS << '(' << *RD << " vtable pointer)\n";
3100 } else if (HasOwnVFPtr) {
3101 PrintOffset(OS, Offset, IndentLevel);
3102 // vfptr (for Microsoft C++ ABI)
3103 OS << '(' << *RD << " vftable pointer)\n";
3107 SmallVector<const CXXRecordDecl *, 4> Bases;
3108 for (const CXXBaseSpecifier &Base : RD->bases()) {
3109 assert(!Base.getType()->isDependentType() &&
3110 "Cannot layout class with dependent bases.");
3111 if (!Base.isVirtual())
3112 Bases.push_back(Base.getType()->getAsCXXRecordDecl());
3115 // Sort nvbases by offset.
3116 std::stable_sort(Bases.begin(), Bases.end(),
3117 [&](const CXXRecordDecl *L, const CXXRecordDecl *R) {
3118 return Layout.getBaseClassOffset(L) < Layout.getBaseClassOffset(R);
3121 // Dump (non-virtual) bases
3122 for (const CXXRecordDecl *Base : Bases) {
3123 CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base);
3124 DumpCXXRecordLayout(OS, Base, C, BaseOffset, IndentLevel,
3125 Base == PrimaryBase ? "(primary base)" : "(base)",
3126 /*IncludeVirtualBases=*/false);
3129 // vbptr (for Microsoft C++ ABI)
3131 PrintOffset(OS, Offset + Layout.getVBPtrOffset(), IndentLevel);
3132 OS << '(' << *RD << " vbtable pointer)\n";
3136 uint64_t FieldNo = 0;
3137 for (CXXRecordDecl::field_iterator I = RD->field_begin(),
3138 E = RD->field_end(); I != E; ++I, ++FieldNo) {
3139 const FieldDecl &Field = **I;
3140 CharUnits FieldOffset = Offset +
3141 C.toCharUnitsFromBits(Layout.getFieldOffset(FieldNo));
3143 if (const CXXRecordDecl *D = Field.getType()->getAsCXXRecordDecl()) {
3144 DumpCXXRecordLayout(OS, D, C, FieldOffset, IndentLevel,
3145 Field.getName().data(),
3146 /*IncludeVirtualBases=*/true);
3150 PrintOffset(OS, FieldOffset, IndentLevel);
3151 OS << Field.getType().getAsString() << ' ' << Field << '\n';
3154 if (!IncludeVirtualBases)
3157 // Dump virtual bases.
3158 const ASTRecordLayout::VBaseOffsetsMapTy &vtordisps =
3159 Layout.getVBaseOffsetsMap();
3160 for (const CXXBaseSpecifier &Base : RD->vbases()) {
3161 assert(Base.isVirtual() && "Found non-virtual class!");
3162 const CXXRecordDecl *VBase = Base.getType()->getAsCXXRecordDecl();
3164 CharUnits VBaseOffset = Offset + Layout.getVBaseClassOffset(VBase);
3166 if (vtordisps.find(VBase)->second.hasVtorDisp()) {
3167 PrintOffset(OS, VBaseOffset - CharUnits::fromQuantity(4), IndentLevel);
3168 OS << "(vtordisp for vbase " << *VBase << ")\n";
3171 DumpCXXRecordLayout(OS, VBase, C, VBaseOffset, IndentLevel,
3172 VBase == PrimaryBase ?
3173 "(primary virtual base)" : "(virtual base)",
3174 /*IncludeVirtualBases=*/false);
3177 PrintIndentNoOffset(OS, IndentLevel - 1);
3178 OS << "[sizeof=" << Layout.getSize().getQuantity();
3179 if (!isMsLayout(RD))
3180 OS << ", dsize=" << Layout.getDataSize().getQuantity();
3181 OS << ", align=" << Layout.getAlignment().getQuantity() << '\n';
3183 PrintIndentNoOffset(OS, IndentLevel - 1);
3184 OS << " nvsize=" << Layout.getNonVirtualSize().getQuantity();
3185 OS << ", nvalign=" << Layout.getNonVirtualAlignment().getQuantity() << "]\n";
3188 void ASTContext::DumpRecordLayout(const RecordDecl *RD,
3190 bool Simple) const {
3191 const ASTRecordLayout &Info = getASTRecordLayout(RD);
3193 if (const CXXRecordDecl *CXXRD = dyn_cast<CXXRecordDecl>(RD))
3195 return DumpCXXRecordLayout(OS, CXXRD, *this, CharUnits(), 0, nullptr,
3196 /*IncludeVirtualBases=*/true);
3198 OS << "Type: " << getTypeDeclType(RD).getAsString() << "\n";
3204 OS << "<ASTRecordLayout\n";
3205 OS << " Size:" << toBits(Info.getSize()) << "\n";
3206 if (!isMsLayout(RD))
3207 OS << " DataSize:" << toBits(Info.getDataSize()) << "\n";
3208 OS << " Alignment:" << toBits(Info.getAlignment()) << "\n";
3209 OS << " FieldOffsets: [";
3210 for (unsigned i = 0, e = Info.getFieldCount(); i != e; ++i) {
3212 OS << Info.getFieldOffset(i);