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/Attr.h"
11 #include "clang/AST/CXXInheritance.h"
12 #include "clang/AST/Decl.h"
13 #include "clang/AST/DeclCXX.h"
14 #include "clang/AST/DeclObjC.h"
15 #include "clang/AST/Expr.h"
16 #include "clang/AST/RecordLayout.h"
17 #include "clang/Basic/TargetInfo.h"
18 #include "clang/Sema/SemaDiagnostic.h"
19 #include "llvm/Support/Format.h"
20 #include "llvm/ADT/SmallSet.h"
21 #include "llvm/Support/MathExtras.h"
22 #include "llvm/Support/CrashRecoveryContext.h"
24 using namespace clang;
28 /// BaseSubobjectInfo - Represents a single base subobject in a complete class.
29 /// For a class hierarchy like
33 /// class C : A, B { };
35 /// The BaseSubobjectInfo graph for C will have three BaseSubobjectInfo
36 /// instances, one for B and two for A.
38 /// If a base is virtual, it will only have one BaseSubobjectInfo allocated.
39 struct BaseSubobjectInfo {
40 /// Class - The class for this base info.
41 const CXXRecordDecl *Class;
43 /// IsVirtual - Whether the BaseInfo represents a virtual base or not.
46 /// Bases - Information about the base subobjects.
47 SmallVector<BaseSubobjectInfo*, 4> Bases;
49 /// PrimaryVirtualBaseInfo - Holds the base info for the primary virtual base
50 /// of this base info (if one exists).
51 BaseSubobjectInfo *PrimaryVirtualBaseInfo;
54 const BaseSubobjectInfo *Derived;
57 /// EmptySubobjectMap - Keeps track of which empty subobjects exist at different
58 /// offsets while laying out a C++ class.
59 class EmptySubobjectMap {
60 const ASTContext &Context;
63 /// Class - The class whose empty entries we're keeping track of.
64 const CXXRecordDecl *Class;
66 /// EmptyClassOffsets - A map from offsets to empty record decls.
67 typedef SmallVector<const CXXRecordDecl *, 1> ClassVectorTy;
68 typedef llvm::DenseMap<CharUnits, ClassVectorTy> EmptyClassOffsetsMapTy;
69 EmptyClassOffsetsMapTy EmptyClassOffsets;
71 /// MaxEmptyClassOffset - The highest offset known to contain an empty
73 CharUnits MaxEmptyClassOffset;
75 /// ComputeEmptySubobjectSizes - Compute the size of the largest base or
76 /// member subobject that is empty.
77 void ComputeEmptySubobjectSizes();
79 void AddSubobjectAtOffset(const CXXRecordDecl *RD, CharUnits Offset);
81 void UpdateEmptyBaseSubobjects(const BaseSubobjectInfo *Info,
82 CharUnits Offset, bool PlacingEmptyBase);
84 void UpdateEmptyFieldSubobjects(const CXXRecordDecl *RD,
85 const CXXRecordDecl *Class,
87 void UpdateEmptyFieldSubobjects(const FieldDecl *FD, CharUnits Offset);
89 /// AnyEmptySubobjectsBeyondOffset - Returns whether there are any empty
90 /// subobjects beyond the given offset.
91 bool AnyEmptySubobjectsBeyondOffset(CharUnits Offset) const {
92 return Offset <= MaxEmptyClassOffset;
96 getFieldOffset(const ASTRecordLayout &Layout, unsigned FieldNo) const {
97 uint64_t FieldOffset = Layout.getFieldOffset(FieldNo);
98 assert(FieldOffset % CharWidth == 0 &&
99 "Field offset not at char boundary!");
101 return Context.toCharUnitsFromBits(FieldOffset);
105 bool CanPlaceSubobjectAtOffset(const CXXRecordDecl *RD,
106 CharUnits Offset) const;
108 bool CanPlaceBaseSubobjectAtOffset(const BaseSubobjectInfo *Info,
111 bool CanPlaceFieldSubobjectAtOffset(const CXXRecordDecl *RD,
112 const CXXRecordDecl *Class,
113 CharUnits Offset) const;
114 bool CanPlaceFieldSubobjectAtOffset(const FieldDecl *FD,
115 CharUnits Offset) const;
118 /// This holds the size of the largest empty subobject (either a base
119 /// or a member). Will be zero if the record being built doesn't contain
120 /// any empty classes.
121 CharUnits SizeOfLargestEmptySubobject;
123 EmptySubobjectMap(const ASTContext &Context, const CXXRecordDecl *Class)
124 : Context(Context), CharWidth(Context.getCharWidth()), Class(Class) {
125 ComputeEmptySubobjectSizes();
128 /// CanPlaceBaseAtOffset - Return whether the given base class can be placed
129 /// at the given offset.
130 /// Returns false if placing the record will result in two components
131 /// (direct or indirect) of the same type having the same offset.
132 bool CanPlaceBaseAtOffset(const BaseSubobjectInfo *Info,
135 /// CanPlaceFieldAtOffset - Return whether a field can be placed at the given
137 bool CanPlaceFieldAtOffset(const FieldDecl *FD, CharUnits Offset);
140 void EmptySubobjectMap::ComputeEmptySubobjectSizes() {
142 for (CXXRecordDecl::base_class_const_iterator I = Class->bases_begin(),
143 E = Class->bases_end(); I != E; ++I) {
144 const CXXRecordDecl *BaseDecl =
145 cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
148 const ASTRecordLayout &Layout = Context.getASTRecordLayout(BaseDecl);
149 if (BaseDecl->isEmpty()) {
150 // If the class decl is empty, get its size.
151 EmptySize = Layout.getSize();
153 // Otherwise, we get the largest empty subobject for the decl.
154 EmptySize = Layout.getSizeOfLargestEmptySubobject();
157 if (EmptySize > SizeOfLargestEmptySubobject)
158 SizeOfLargestEmptySubobject = EmptySize;
162 for (CXXRecordDecl::field_iterator I = Class->field_begin(),
163 E = Class->field_end(); I != E; ++I) {
164 const FieldDecl *FD = *I;
166 const RecordType *RT =
167 Context.getBaseElementType(FD->getType())->getAs<RecordType>();
169 // We only care about record types.
174 const CXXRecordDecl *MemberDecl = cast<CXXRecordDecl>(RT->getDecl());
175 const ASTRecordLayout &Layout = Context.getASTRecordLayout(MemberDecl);
176 if (MemberDecl->isEmpty()) {
177 // If the class decl is empty, get its size.
178 EmptySize = Layout.getSize();
180 // Otherwise, we get the largest empty subobject for the decl.
181 EmptySize = Layout.getSizeOfLargestEmptySubobject();
184 if (EmptySize > SizeOfLargestEmptySubobject)
185 SizeOfLargestEmptySubobject = EmptySize;
190 EmptySubobjectMap::CanPlaceSubobjectAtOffset(const CXXRecordDecl *RD,
191 CharUnits Offset) const {
192 // We only need to check empty bases.
196 EmptyClassOffsetsMapTy::const_iterator I = EmptyClassOffsets.find(Offset);
197 if (I == EmptyClassOffsets.end())
200 const ClassVectorTy& Classes = I->second;
201 if (std::find(Classes.begin(), Classes.end(), RD) == Classes.end())
204 // There is already an empty class of the same type at this offset.
208 void EmptySubobjectMap::AddSubobjectAtOffset(const CXXRecordDecl *RD,
210 // We only care about empty bases.
214 // If we have empty structures inside an union, we can assign both
215 // the same offset. Just avoid pushing them twice in the list.
216 ClassVectorTy& Classes = EmptyClassOffsets[Offset];
217 if (std::find(Classes.begin(), Classes.end(), RD) != Classes.end())
220 Classes.push_back(RD);
222 // Update the empty class offset.
223 if (Offset > MaxEmptyClassOffset)
224 MaxEmptyClassOffset = Offset;
228 EmptySubobjectMap::CanPlaceBaseSubobjectAtOffset(const BaseSubobjectInfo *Info,
230 // We don't have to keep looking past the maximum offset that's known to
231 // contain an empty class.
232 if (!AnyEmptySubobjectsBeyondOffset(Offset))
235 if (!CanPlaceSubobjectAtOffset(Info->Class, Offset))
238 // Traverse all non-virtual bases.
239 const ASTRecordLayout &Layout = Context.getASTRecordLayout(Info->Class);
240 for (unsigned I = 0, E = Info->Bases.size(); I != E; ++I) {
241 BaseSubobjectInfo* Base = Info->Bases[I];
245 CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base->Class);
247 if (!CanPlaceBaseSubobjectAtOffset(Base, BaseOffset))
251 if (Info->PrimaryVirtualBaseInfo) {
252 BaseSubobjectInfo *PrimaryVirtualBaseInfo = Info->PrimaryVirtualBaseInfo;
254 if (Info == PrimaryVirtualBaseInfo->Derived) {
255 if (!CanPlaceBaseSubobjectAtOffset(PrimaryVirtualBaseInfo, Offset))
260 // Traverse all member variables.
261 unsigned FieldNo = 0;
262 for (CXXRecordDecl::field_iterator I = Info->Class->field_begin(),
263 E = Info->Class->field_end(); I != E; ++I, ++FieldNo) {
264 const FieldDecl *FD = *I;
265 if (FD->isBitField())
268 CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
269 if (!CanPlaceFieldSubobjectAtOffset(FD, FieldOffset))
276 void EmptySubobjectMap::UpdateEmptyBaseSubobjects(const BaseSubobjectInfo *Info,
278 bool PlacingEmptyBase) {
279 if (!PlacingEmptyBase && Offset >= SizeOfLargestEmptySubobject) {
280 // We know that the only empty subobjects that can conflict with empty
281 // subobject of non-empty bases, are empty bases that can be placed at
282 // offset zero. Because of this, we only need to keep track of empty base
283 // subobjects with offsets less than the size of the largest empty
284 // subobject for our class.
288 AddSubobjectAtOffset(Info->Class, Offset);
290 // Traverse all non-virtual bases.
291 const ASTRecordLayout &Layout = Context.getASTRecordLayout(Info->Class);
292 for (unsigned I = 0, E = Info->Bases.size(); I != E; ++I) {
293 BaseSubobjectInfo* Base = Info->Bases[I];
297 CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base->Class);
298 UpdateEmptyBaseSubobjects(Base, BaseOffset, PlacingEmptyBase);
301 if (Info->PrimaryVirtualBaseInfo) {
302 BaseSubobjectInfo *PrimaryVirtualBaseInfo = Info->PrimaryVirtualBaseInfo;
304 if (Info == PrimaryVirtualBaseInfo->Derived)
305 UpdateEmptyBaseSubobjects(PrimaryVirtualBaseInfo, Offset,
309 // Traverse all member variables.
310 unsigned FieldNo = 0;
311 for (CXXRecordDecl::field_iterator I = Info->Class->field_begin(),
312 E = Info->Class->field_end(); I != E; ++I, ++FieldNo) {
313 const FieldDecl *FD = *I;
314 if (FD->isBitField())
317 CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
318 UpdateEmptyFieldSubobjects(FD, FieldOffset);
322 bool EmptySubobjectMap::CanPlaceBaseAtOffset(const BaseSubobjectInfo *Info,
324 // If we know this class doesn't have any empty subobjects we don't need to
326 if (SizeOfLargestEmptySubobject.isZero())
329 if (!CanPlaceBaseSubobjectAtOffset(Info, Offset))
332 // We are able to place the base at this offset. Make sure to update the
333 // empty base subobject map.
334 UpdateEmptyBaseSubobjects(Info, Offset, Info->Class->isEmpty());
339 EmptySubobjectMap::CanPlaceFieldSubobjectAtOffset(const CXXRecordDecl *RD,
340 const CXXRecordDecl *Class,
341 CharUnits Offset) const {
342 // We don't have to keep looking past the maximum offset that's known to
343 // contain an empty class.
344 if (!AnyEmptySubobjectsBeyondOffset(Offset))
347 if (!CanPlaceSubobjectAtOffset(RD, Offset))
350 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
352 // Traverse all non-virtual bases.
353 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
354 E = RD->bases_end(); I != E; ++I) {
358 const CXXRecordDecl *BaseDecl =
359 cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
361 CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(BaseDecl);
362 if (!CanPlaceFieldSubobjectAtOffset(BaseDecl, Class, BaseOffset))
367 // This is the most derived class, traverse virtual bases as well.
368 for (CXXRecordDecl::base_class_const_iterator I = RD->vbases_begin(),
369 E = RD->vbases_end(); I != E; ++I) {
370 const CXXRecordDecl *VBaseDecl =
371 cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
373 CharUnits VBaseOffset = Offset + Layout.getVBaseClassOffset(VBaseDecl);
374 if (!CanPlaceFieldSubobjectAtOffset(VBaseDecl, Class, VBaseOffset))
379 // Traverse all member variables.
380 unsigned FieldNo = 0;
381 for (CXXRecordDecl::field_iterator I = RD->field_begin(), E = RD->field_end();
382 I != E; ++I, ++FieldNo) {
383 const FieldDecl *FD = *I;
384 if (FD->isBitField())
387 CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
389 if (!CanPlaceFieldSubobjectAtOffset(FD, FieldOffset))
397 EmptySubobjectMap::CanPlaceFieldSubobjectAtOffset(const FieldDecl *FD,
398 CharUnits Offset) const {
399 // We don't have to keep looking past the maximum offset that's known to
400 // contain an empty class.
401 if (!AnyEmptySubobjectsBeyondOffset(Offset))
404 QualType T = FD->getType();
405 if (const RecordType *RT = T->getAs<RecordType>()) {
406 const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
407 return CanPlaceFieldSubobjectAtOffset(RD, RD, Offset);
410 // If we have an array type we need to look at every element.
411 if (const ConstantArrayType *AT = Context.getAsConstantArrayType(T)) {
412 QualType ElemTy = Context.getBaseElementType(AT);
413 const RecordType *RT = ElemTy->getAs<RecordType>();
417 const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
418 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
420 uint64_t NumElements = Context.getConstantArrayElementCount(AT);
421 CharUnits ElementOffset = Offset;
422 for (uint64_t I = 0; I != NumElements; ++I) {
423 // We don't have to keep looking past the maximum offset that's known to
424 // contain an empty class.
425 if (!AnyEmptySubobjectsBeyondOffset(ElementOffset))
428 if (!CanPlaceFieldSubobjectAtOffset(RD, RD, ElementOffset))
431 ElementOffset += Layout.getSize();
439 EmptySubobjectMap::CanPlaceFieldAtOffset(const FieldDecl *FD,
441 if (!CanPlaceFieldSubobjectAtOffset(FD, Offset))
444 // We are able to place the member variable at this offset.
445 // Make sure to update the empty base subobject map.
446 UpdateEmptyFieldSubobjects(FD, Offset);
450 void EmptySubobjectMap::UpdateEmptyFieldSubobjects(const CXXRecordDecl *RD,
451 const CXXRecordDecl *Class,
453 // We know that the only empty subobjects that can conflict with empty
454 // field subobjects are subobjects of empty bases that can be placed at offset
455 // zero. Because of this, we only need to keep track of empty field
456 // subobjects with offsets less than the size of the largest empty
457 // subobject for our class.
458 if (Offset >= SizeOfLargestEmptySubobject)
461 AddSubobjectAtOffset(RD, Offset);
463 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
465 // Traverse all non-virtual bases.
466 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
467 E = RD->bases_end(); I != E; ++I) {
471 const CXXRecordDecl *BaseDecl =
472 cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
474 CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(BaseDecl);
475 UpdateEmptyFieldSubobjects(BaseDecl, Class, BaseOffset);
479 // This is the most derived class, traverse virtual bases as well.
480 for (CXXRecordDecl::base_class_const_iterator I = RD->vbases_begin(),
481 E = RD->vbases_end(); I != E; ++I) {
482 const CXXRecordDecl *VBaseDecl =
483 cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
485 CharUnits VBaseOffset = Offset + Layout.getVBaseClassOffset(VBaseDecl);
486 UpdateEmptyFieldSubobjects(VBaseDecl, Class, VBaseOffset);
490 // Traverse all member variables.
491 unsigned FieldNo = 0;
492 for (CXXRecordDecl::field_iterator I = RD->field_begin(), E = RD->field_end();
493 I != E; ++I, ++FieldNo) {
494 const FieldDecl *FD = *I;
495 if (FD->isBitField())
498 CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
500 UpdateEmptyFieldSubobjects(FD, FieldOffset);
504 void EmptySubobjectMap::UpdateEmptyFieldSubobjects(const FieldDecl *FD,
506 QualType T = FD->getType();
507 if (const RecordType *RT = T->getAs<RecordType>()) {
508 const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
509 UpdateEmptyFieldSubobjects(RD, RD, Offset);
513 // If we have an array type we need to update every element.
514 if (const ConstantArrayType *AT = Context.getAsConstantArrayType(T)) {
515 QualType ElemTy = Context.getBaseElementType(AT);
516 const RecordType *RT = ElemTy->getAs<RecordType>();
520 const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
521 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
523 uint64_t NumElements = Context.getConstantArrayElementCount(AT);
524 CharUnits ElementOffset = Offset;
526 for (uint64_t I = 0; I != NumElements; ++I) {
527 // We know that the only empty subobjects that can conflict with empty
528 // field subobjects are subobjects of empty bases that can be placed at
529 // offset zero. Because of this, we only need to keep track of empty field
530 // subobjects with offsets less than the size of the largest empty
531 // subobject for our class.
532 if (ElementOffset >= SizeOfLargestEmptySubobject)
535 UpdateEmptyFieldSubobjects(RD, RD, ElementOffset);
536 ElementOffset += Layout.getSize();
541 class RecordLayoutBuilder {
543 // FIXME: Remove this and make the appropriate fields public.
544 friend class clang::ASTContext;
546 const ASTContext &Context;
548 EmptySubobjectMap *EmptySubobjects;
550 /// Size - The current size of the record layout.
553 /// Alignment - The current alignment of the record layout.
556 /// \brief The alignment if attribute packed is not used.
557 CharUnits UnpackedAlignment;
559 SmallVector<uint64_t, 16> FieldOffsets;
561 /// Packed - Whether the record is packed or not.
564 unsigned IsUnion : 1;
566 unsigned IsMac68kAlign : 1;
568 unsigned IsMsStruct : 1;
570 /// UnfilledBitsInLastByte - If the last field laid out was a bitfield,
571 /// this contains the number of bits in the last byte that can be used for
572 /// an adjacent bitfield if necessary.
573 unsigned char UnfilledBitsInLastByte;
575 /// MaxFieldAlignment - The maximum allowed field alignment. This is set by
577 CharUnits MaxFieldAlignment;
579 /// DataSize - The data size of the record being laid out.
582 CharUnits NonVirtualSize;
583 CharUnits NonVirtualAlignment;
585 FieldDecl *ZeroLengthBitfield;
587 /// PrimaryBase - the primary base class (if one exists) of the class
588 /// we're laying out.
589 const CXXRecordDecl *PrimaryBase;
591 /// PrimaryBaseIsVirtual - Whether the primary base of the class we're laying
593 bool PrimaryBaseIsVirtual;
595 /// VBPtrOffset - Virtual base table offset. Only for MS layout.
596 CharUnits VBPtrOffset;
598 typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsetsMapTy;
600 /// Bases - base classes and their offsets in the record.
601 BaseOffsetsMapTy Bases;
603 // VBases - virtual base classes and their offsets in the record.
604 BaseOffsetsMapTy VBases;
606 /// IndirectPrimaryBases - Virtual base classes, direct or indirect, that are
607 /// primary base classes for some other direct or indirect base class.
608 CXXIndirectPrimaryBaseSet IndirectPrimaryBases;
610 /// FirstNearlyEmptyVBase - The first nearly empty virtual base class in
611 /// inheritance graph order. Used for determining the primary base class.
612 const CXXRecordDecl *FirstNearlyEmptyVBase;
614 /// VisitedVirtualBases - A set of all the visited virtual bases, used to
615 /// avoid visiting virtual bases more than once.
616 llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBases;
618 RecordLayoutBuilder(const ASTContext &Context, EmptySubobjectMap
619 *EmptySubobjects, CharUnits Alignment)
620 : Context(Context), EmptySubobjects(EmptySubobjects), Size(0),
621 Alignment(Alignment), UnpackedAlignment(Alignment),
622 Packed(false), IsUnion(false),
623 IsMac68kAlign(false), IsMsStruct(false),
624 UnfilledBitsInLastByte(0), MaxFieldAlignment(CharUnits::Zero()),
625 DataSize(0), NonVirtualSize(CharUnits::Zero()),
626 NonVirtualAlignment(CharUnits::One()),
627 ZeroLengthBitfield(0), PrimaryBase(0),
628 PrimaryBaseIsVirtual(false), VBPtrOffset(CharUnits::fromQuantity(-1)),
629 FirstNearlyEmptyVBase(0) { }
631 void Layout(const RecordDecl *D);
632 void Layout(const CXXRecordDecl *D);
633 void Layout(const ObjCInterfaceDecl *D);
635 void LayoutFields(const RecordDecl *D);
636 void LayoutField(const FieldDecl *D);
637 void LayoutWideBitField(uint64_t FieldSize, uint64_t TypeSize,
638 bool FieldPacked, const FieldDecl *D);
639 void LayoutBitField(const FieldDecl *D);
640 void MSLayoutVirtualBases(const CXXRecordDecl *RD);
641 void MSLayout(const CXXRecordDecl *RD);
643 /// BaseSubobjectInfoAllocator - Allocator for BaseSubobjectInfo objects.
644 llvm::SpecificBumpPtrAllocator<BaseSubobjectInfo> BaseSubobjectInfoAllocator;
646 typedef llvm::DenseMap<const CXXRecordDecl *, BaseSubobjectInfo *>
647 BaseSubobjectInfoMapTy;
649 /// VirtualBaseInfo - Map from all the (direct or indirect) virtual bases
650 /// of the class we're laying out to their base subobject info.
651 BaseSubobjectInfoMapTy VirtualBaseInfo;
653 /// NonVirtualBaseInfo - Map from all the direct non-virtual bases of the
654 /// class we're laying out to their base subobject info.
655 BaseSubobjectInfoMapTy NonVirtualBaseInfo;
657 /// ComputeBaseSubobjectInfo - Compute the base subobject information for the
658 /// bases of the given class.
659 void ComputeBaseSubobjectInfo(const CXXRecordDecl *RD);
661 /// ComputeBaseSubobjectInfo - Compute the base subobject information for a
662 /// single class and all of its base classes.
663 BaseSubobjectInfo *ComputeBaseSubobjectInfo(const CXXRecordDecl *RD,
665 BaseSubobjectInfo *Derived);
667 /// DeterminePrimaryBase - Determine the primary base of the given class.
668 void DeterminePrimaryBase(const CXXRecordDecl *RD);
670 void SelectPrimaryVBase(const CXXRecordDecl *RD);
672 CharUnits GetVirtualPointersSize(const CXXRecordDecl *RD) const;
674 /// LayoutNonVirtualBases - Determines the primary base class (if any) and
675 /// lays it out. Will then proceed to lay out all non-virtual base clasess.
676 void LayoutNonVirtualBases(const CXXRecordDecl *RD);
678 /// LayoutNonVirtualBase - Lays out a single non-virtual base.
679 void LayoutNonVirtualBase(const BaseSubobjectInfo *Base);
681 void AddPrimaryVirtualBaseOffsets(const BaseSubobjectInfo *Info,
684 /// LayoutVirtualBases - Lays out all the virtual bases.
685 void LayoutVirtualBases(const CXXRecordDecl *RD,
686 const CXXRecordDecl *MostDerivedClass);
688 /// LayoutVirtualBase - Lays out a single virtual base.
689 void LayoutVirtualBase(const BaseSubobjectInfo *Base);
691 /// LayoutBase - Will lay out a base and return the offset where it was
692 /// placed, in chars.
693 CharUnits LayoutBase(const BaseSubobjectInfo *Base);
695 /// InitializeLayout - Initialize record layout for the given record decl.
696 void InitializeLayout(const Decl *D);
698 /// FinishLayout - Finalize record layout. Adjust record size based on the
700 void FinishLayout(const NamedDecl *D);
702 void UpdateAlignment(CharUnits NewAlignment, CharUnits UnpackedNewAlignment);
703 void UpdateAlignment(CharUnits NewAlignment) {
704 UpdateAlignment(NewAlignment, NewAlignment);
707 void CheckFieldPadding(uint64_t Offset, uint64_t UnpaddedOffset,
708 uint64_t UnpackedOffset, unsigned UnpackedAlign,
709 bool isPacked, const FieldDecl *D);
711 DiagnosticBuilder Diag(SourceLocation Loc, unsigned DiagID);
713 CharUnits getSize() const {
714 assert(Size % Context.getCharWidth() == 0);
715 return Context.toCharUnitsFromBits(Size);
717 uint64_t getSizeInBits() const { return Size; }
719 void setSize(CharUnits NewSize) { Size = Context.toBits(NewSize); }
720 void setSize(uint64_t NewSize) { Size = NewSize; }
722 CharUnits getAligment() const { return Alignment; }
724 CharUnits getDataSize() const {
725 assert(DataSize % Context.getCharWidth() == 0);
726 return Context.toCharUnitsFromBits(DataSize);
728 uint64_t getDataSizeInBits() const { return DataSize; }
730 void setDataSize(CharUnits NewSize) { DataSize = Context.toBits(NewSize); }
731 void setDataSize(uint64_t NewSize) { DataSize = NewSize; }
733 bool HasVBPtr(const CXXRecordDecl *RD) const;
734 bool HasNewVirtualFunction(const CXXRecordDecl *RD) const;
736 /// Add vbptr or vfptr to layout.
739 RecordLayoutBuilder(const RecordLayoutBuilder&); // DO NOT IMPLEMENT
740 void operator=(const RecordLayoutBuilder&); // DO NOT IMPLEMENT
742 static const CXXMethodDecl *ComputeKeyFunction(const CXXRecordDecl *RD);
744 virtual ~RecordLayoutBuilder() { }
746 CharUnits GetVBPtrOffset() const { return VBPtrOffset; }
748 } // end anonymous namespace
751 RecordLayoutBuilder::SelectPrimaryVBase(const CXXRecordDecl *RD) {
752 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
753 E = RD->bases_end(); I != E; ++I) {
754 assert(!I->getType()->isDependentType() &&
755 "Cannot layout class with dependent bases.");
757 const CXXRecordDecl *Base =
758 cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
760 // Check if this is a nearly empty virtual base.
761 if (I->isVirtual() && Context.isNearlyEmpty(Base)) {
762 // If it's not an indirect primary base, then we've found our primary
764 if (!IndirectPrimaryBases.count(Base)) {
766 PrimaryBaseIsVirtual = true;
770 // Is this the first nearly empty virtual base?
771 if (!FirstNearlyEmptyVBase)
772 FirstNearlyEmptyVBase = Base;
775 SelectPrimaryVBase(Base);
782 RecordLayoutBuilder::GetVirtualPointersSize(const CXXRecordDecl *RD) const {
783 return Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
786 /// DeterminePrimaryBase - Determine the primary base of the given class.
787 void RecordLayoutBuilder::DeterminePrimaryBase(const CXXRecordDecl *RD) {
788 // If the class isn't dynamic, it won't have a primary base.
789 if (!RD->isDynamicClass())
792 // Compute all the primary virtual bases for all of our direct and
793 // indirect bases, and record all their primary virtual base classes.
794 RD->getIndirectPrimaryBases(IndirectPrimaryBases);
796 // If the record has a dynamic base class, attempt to choose a primary base
797 // class. It is the first (in direct base class order) non-virtual dynamic
798 // base class, if one exists.
799 for (CXXRecordDecl::base_class_const_iterator i = RD->bases_begin(),
800 e = RD->bases_end(); i != e; ++i) {
801 // Ignore virtual bases.
805 const CXXRecordDecl *Base =
806 cast<CXXRecordDecl>(i->getType()->getAs<RecordType>()->getDecl());
808 if (Base->isDynamicClass()) {
811 PrimaryBaseIsVirtual = false;
816 // Otherwise, it is the first nearly empty virtual base that is not an
817 // indirect primary virtual base class, if one exists.
818 if (RD->getNumVBases() != 0) {
819 SelectPrimaryVBase(RD);
824 // Otherwise, it is the first nearly empty virtual base that is not an
825 // indirect primary virtual base class, if one exists.
826 if (FirstNearlyEmptyVBase) {
827 PrimaryBase = FirstNearlyEmptyVBase;
828 PrimaryBaseIsVirtual = true;
832 // Otherwise there is no primary base class.
833 assert(!PrimaryBase && "Should not get here with a primary base!");
835 // Allocate the virtual table pointer at offset zero.
836 assert(DataSize == 0 && "Vtable pointer must be at offset zero!");
839 setSize(getSize() + GetVirtualPointersSize(RD));
840 setDataSize(getSize());
842 CharUnits UnpackedBaseAlign =
843 Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerAlign(0));
844 CharUnits BaseAlign = (Packed) ? CharUnits::One() : UnpackedBaseAlign;
846 // The maximum field alignment overrides base align.
847 if (!MaxFieldAlignment.isZero()) {
848 BaseAlign = std::min(BaseAlign, MaxFieldAlignment);
849 UnpackedBaseAlign = std::min(UnpackedBaseAlign, MaxFieldAlignment);
852 // Update the alignment.
853 UpdateAlignment(BaseAlign, UnpackedBaseAlign);
857 RecordLayoutBuilder::ComputeBaseSubobjectInfo(const CXXRecordDecl *RD,
859 BaseSubobjectInfo *Derived) {
860 BaseSubobjectInfo *Info;
863 // Check if we already have info about this virtual base.
864 BaseSubobjectInfo *&InfoSlot = VirtualBaseInfo[RD];
866 assert(InfoSlot->Class == RD && "Wrong class for virtual base info!");
870 // We don't, create it.
871 InfoSlot = new (BaseSubobjectInfoAllocator.Allocate()) BaseSubobjectInfo;
874 Info = new (BaseSubobjectInfoAllocator.Allocate()) BaseSubobjectInfo;
878 Info->IsVirtual = IsVirtual;
880 Info->PrimaryVirtualBaseInfo = 0;
882 const CXXRecordDecl *PrimaryVirtualBase = 0;
883 BaseSubobjectInfo *PrimaryVirtualBaseInfo = 0;
885 // Check if this base has a primary virtual base.
886 if (RD->getNumVBases()) {
887 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
888 if (Layout.isPrimaryBaseVirtual()) {
889 // This base does have a primary virtual base.
890 PrimaryVirtualBase = Layout.getPrimaryBase();
891 assert(PrimaryVirtualBase && "Didn't have a primary virtual base!");
893 // Now check if we have base subobject info about this primary base.
894 PrimaryVirtualBaseInfo = VirtualBaseInfo.lookup(PrimaryVirtualBase);
896 if (PrimaryVirtualBaseInfo) {
897 if (PrimaryVirtualBaseInfo->Derived) {
898 // We did have info about this primary base, and it turns out that it
899 // has already been claimed as a primary virtual base for another
901 PrimaryVirtualBase = 0;
903 // We can claim this base as our primary base.
904 Info->PrimaryVirtualBaseInfo = PrimaryVirtualBaseInfo;
905 PrimaryVirtualBaseInfo->Derived = Info;
911 // Now go through all direct bases.
912 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
913 E = RD->bases_end(); I != E; ++I) {
914 bool IsVirtual = I->isVirtual();
916 const CXXRecordDecl *BaseDecl =
917 cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
919 Info->Bases.push_back(ComputeBaseSubobjectInfo(BaseDecl, IsVirtual, Info));
922 if (PrimaryVirtualBase && !PrimaryVirtualBaseInfo) {
923 // Traversing the bases must have created the base info for our primary
925 PrimaryVirtualBaseInfo = VirtualBaseInfo.lookup(PrimaryVirtualBase);
926 assert(PrimaryVirtualBaseInfo &&
927 "Did not create a primary virtual base!");
929 // Claim the primary virtual base as our primary virtual base.
930 Info->PrimaryVirtualBaseInfo = PrimaryVirtualBaseInfo;
931 PrimaryVirtualBaseInfo->Derived = Info;
937 void RecordLayoutBuilder::ComputeBaseSubobjectInfo(const CXXRecordDecl *RD) {
938 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
939 E = RD->bases_end(); I != E; ++I) {
940 bool IsVirtual = I->isVirtual();
942 const CXXRecordDecl *BaseDecl =
943 cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
945 // Compute the base subobject info for this base.
946 BaseSubobjectInfo *Info = ComputeBaseSubobjectInfo(BaseDecl, IsVirtual, 0);
949 // ComputeBaseInfo has already added this base for us.
950 assert(VirtualBaseInfo.count(BaseDecl) &&
951 "Did not add virtual base!");
953 // Add the base info to the map of non-virtual bases.
954 assert(!NonVirtualBaseInfo.count(BaseDecl) &&
955 "Non-virtual base already exists!");
956 NonVirtualBaseInfo.insert(std::make_pair(BaseDecl, Info));
962 RecordLayoutBuilder::LayoutNonVirtualBases(const CXXRecordDecl *RD) {
963 // Then, determine the primary base class.
964 DeterminePrimaryBase(RD);
966 // Compute base subobject info.
967 ComputeBaseSubobjectInfo(RD);
969 // If we have a primary base class, lay it out.
971 if (PrimaryBaseIsVirtual) {
972 // If the primary virtual base was a primary virtual base of some other
973 // base class we'll have to steal it.
974 BaseSubobjectInfo *PrimaryBaseInfo = VirtualBaseInfo.lookup(PrimaryBase);
975 PrimaryBaseInfo->Derived = 0;
977 // We have a virtual primary base, insert it as an indirect primary base.
978 IndirectPrimaryBases.insert(PrimaryBase);
980 assert(!VisitedVirtualBases.count(PrimaryBase) &&
981 "vbase already visited!");
982 VisitedVirtualBases.insert(PrimaryBase);
984 LayoutVirtualBase(PrimaryBaseInfo);
986 BaseSubobjectInfo *PrimaryBaseInfo =
987 NonVirtualBaseInfo.lookup(PrimaryBase);
988 assert(PrimaryBaseInfo &&
989 "Did not find base info for non-virtual primary base!");
991 LayoutNonVirtualBase(PrimaryBaseInfo);
995 // Now lay out the non-virtual bases.
996 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
997 E = RD->bases_end(); I != E; ++I) {
999 // Ignore virtual bases.
1003 const CXXRecordDecl *BaseDecl =
1004 cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
1006 // Skip the primary base.
1007 if (BaseDecl == PrimaryBase && !PrimaryBaseIsVirtual)
1010 // Lay out the base.
1011 BaseSubobjectInfo *BaseInfo = NonVirtualBaseInfo.lookup(BaseDecl);
1012 assert(BaseInfo && "Did not find base info for non-virtual base!");
1014 LayoutNonVirtualBase(BaseInfo);
1018 void RecordLayoutBuilder::LayoutNonVirtualBase(const BaseSubobjectInfo *Base) {
1020 CharUnits Offset = LayoutBase(Base);
1022 // Add its base class offset.
1023 assert(!Bases.count(Base->Class) && "base offset already exists!");
1024 Bases.insert(std::make_pair(Base->Class, Offset));
1026 AddPrimaryVirtualBaseOffsets(Base, Offset);
1030 RecordLayoutBuilder::AddPrimaryVirtualBaseOffsets(const BaseSubobjectInfo *Info,
1032 // This base isn't interesting, it has no virtual bases.
1033 if (!Info->Class->getNumVBases())
1036 // First, check if we have a virtual primary base to add offsets for.
1037 if (Info->PrimaryVirtualBaseInfo) {
1038 assert(Info->PrimaryVirtualBaseInfo->IsVirtual &&
1039 "Primary virtual base is not virtual!");
1040 if (Info->PrimaryVirtualBaseInfo->Derived == Info) {
1042 assert(!VBases.count(Info->PrimaryVirtualBaseInfo->Class) &&
1043 "primary vbase offset already exists!");
1044 VBases.insert(std::make_pair(Info->PrimaryVirtualBaseInfo->Class,
1047 // Traverse the primary virtual base.
1048 AddPrimaryVirtualBaseOffsets(Info->PrimaryVirtualBaseInfo, Offset);
1052 // Now go through all direct non-virtual bases.
1053 const ASTRecordLayout &Layout = Context.getASTRecordLayout(Info->Class);
1054 for (unsigned I = 0, E = Info->Bases.size(); I != E; ++I) {
1055 const BaseSubobjectInfo *Base = Info->Bases[I];
1056 if (Base->IsVirtual)
1059 CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base->Class);
1060 AddPrimaryVirtualBaseOffsets(Base, BaseOffset);
1064 void RecordLayoutBuilder::AddVPointer() {
1065 CharUnits PtrWidth =
1066 Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
1067 setSize(getSize() + PtrWidth);
1068 setDataSize(getSize());
1070 if (Alignment > PtrWidth) {
1071 setSize(getSize() + (Alignment - PtrWidth));
1072 setDataSize(getSize());
1077 RecordLayoutBuilder::HasNewVirtualFunction(const CXXRecordDecl *RD) const {
1078 for (CXXRecordDecl::method_iterator method = RD->method_begin();
1079 method != RD->method_end();
1081 if (method->isVirtual() &&
1082 !method->size_overridden_methods()) {
1090 RecordLayoutBuilder::HasVBPtr(const CXXRecordDecl *RD) const {
1091 if (!RD->getNumBases())
1094 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
1095 E = RD->bases_end(); I != E; ++I) {
1096 if (!I->isVirtual()) {
1104 RecordLayoutBuilder::LayoutVirtualBases(const CXXRecordDecl *RD,
1105 const CXXRecordDecl *MostDerivedClass) {
1106 const CXXRecordDecl *PrimaryBase;
1107 bool PrimaryBaseIsVirtual;
1109 if (MostDerivedClass == RD) {
1110 PrimaryBase = this->PrimaryBase;
1111 PrimaryBaseIsVirtual = this->PrimaryBaseIsVirtual;
1113 const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
1114 PrimaryBase = Layout.getPrimaryBase();
1115 PrimaryBaseIsVirtual = Layout.isPrimaryBaseVirtual();
1118 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
1119 E = RD->bases_end(); I != E; ++I) {
1120 assert(!I->getType()->isDependentType() &&
1121 "Cannot layout class with dependent bases.");
1123 const CXXRecordDecl *BaseDecl =
1124 cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
1126 if (I->isVirtual()) {
1127 if (PrimaryBase != BaseDecl || !PrimaryBaseIsVirtual) {
1128 bool IndirectPrimaryBase = IndirectPrimaryBases.count(BaseDecl);
1130 // Only lay out the virtual base if it's not an indirect primary base.
1131 if (!IndirectPrimaryBase) {
1132 // Only visit virtual bases once.
1133 if (!VisitedVirtualBases.insert(BaseDecl))
1136 const BaseSubobjectInfo *BaseInfo = VirtualBaseInfo.lookup(BaseDecl);
1137 assert(BaseInfo && "Did not find virtual base info!");
1138 LayoutVirtualBase(BaseInfo);
1143 if (!BaseDecl->getNumVBases()) {
1144 // This base isn't interesting since it doesn't have any virtual bases.
1148 LayoutVirtualBases(BaseDecl, MostDerivedClass);
1152 void RecordLayoutBuilder::LayoutVirtualBase(const BaseSubobjectInfo *Base) {
1153 assert(!Base->Derived && "Trying to lay out a primary virtual base!");
1156 CharUnits Offset = LayoutBase(Base);
1158 // Add its base class offset.
1159 assert(!VBases.count(Base->Class) && "vbase offset already exists!");
1160 VBases.insert(std::make_pair(Base->Class, Offset));
1162 AddPrimaryVirtualBaseOffsets(Base, Offset);
1165 CharUnits RecordLayoutBuilder::LayoutBase(const BaseSubobjectInfo *Base) {
1166 const ASTRecordLayout &Layout = Context.getASTRecordLayout(Base->Class);
1168 // If we have an empty base class, try to place it at offset 0.
1169 if (Base->Class->isEmpty() &&
1170 EmptySubobjects->CanPlaceBaseAtOffset(Base, CharUnits::Zero())) {
1171 setSize(std::max(getSize(), Layout.getSize()));
1173 return CharUnits::Zero();
1176 CharUnits UnpackedBaseAlign = Layout.getNonVirtualAlign();
1177 CharUnits BaseAlign = (Packed) ? CharUnits::One() : UnpackedBaseAlign;
1179 // The maximum field alignment overrides base align.
1180 if (!MaxFieldAlignment.isZero()) {
1181 BaseAlign = std::min(BaseAlign, MaxFieldAlignment);
1182 UnpackedBaseAlign = std::min(UnpackedBaseAlign, MaxFieldAlignment);
1185 // Round up the current record size to the base's alignment boundary.
1186 CharUnits Offset = getDataSize().RoundUpToAlignment(BaseAlign);
1188 // Try to place the base.
1189 while (!EmptySubobjects->CanPlaceBaseAtOffset(Base, Offset))
1190 Offset += BaseAlign;
1192 if (!Base->Class->isEmpty()) {
1193 // Update the data size.
1194 setDataSize(Offset + Layout.getNonVirtualSize());
1196 setSize(std::max(getSize(), getDataSize()));
1198 setSize(std::max(getSize(), Offset + Layout.getSize()));
1200 // Remember max struct/class alignment.
1201 UpdateAlignment(BaseAlign, UnpackedBaseAlign);
1206 void RecordLayoutBuilder::InitializeLayout(const Decl *D) {
1207 if (const RecordDecl *RD = dyn_cast<RecordDecl>(D))
1208 IsUnion = RD->isUnion();
1210 Packed = D->hasAttr<PackedAttr>();
1212 IsMsStruct = D->hasAttr<MsStructAttr>();
1214 // Honor the default struct packing maximum alignment flag.
1215 if (unsigned DefaultMaxFieldAlignment = Context.getLangOptions().PackStruct) {
1216 MaxFieldAlignment = CharUnits::fromQuantity(DefaultMaxFieldAlignment);
1219 // mac68k alignment supersedes maximum field alignment and attribute aligned,
1220 // and forces all structures to have 2-byte alignment. The IBM docs on it
1221 // allude to additional (more complicated) semantics, especially with regard
1222 // to bit-fields, but gcc appears not to follow that.
1223 if (D->hasAttr<AlignMac68kAttr>()) {
1224 IsMac68kAlign = true;
1225 MaxFieldAlignment = CharUnits::fromQuantity(2);
1226 Alignment = CharUnits::fromQuantity(2);
1228 if (const MaxFieldAlignmentAttr *MFAA = D->getAttr<MaxFieldAlignmentAttr>())
1229 MaxFieldAlignment = Context.toCharUnitsFromBits(MFAA->getAlignment());
1231 if (unsigned MaxAlign = D->getMaxAlignment())
1232 UpdateAlignment(Context.toCharUnitsFromBits(MaxAlign));
1236 void RecordLayoutBuilder::Layout(const RecordDecl *D) {
1237 InitializeLayout(D);
1240 // Finally, round the size of the total struct up to the alignment of the
1245 void RecordLayoutBuilder::Layout(const CXXRecordDecl *RD) {
1246 if (Context.getTargetInfo().getCXXABI() == CXXABI_Microsoft) {
1251 InitializeLayout(RD);
1253 // Lay out the vtable and the non-virtual bases.
1254 LayoutNonVirtualBases(RD);
1258 NonVirtualSize = Context.toCharUnitsFromBits(
1259 llvm::RoundUpToAlignment(getSizeInBits(),
1260 Context.getTargetInfo().getCharAlign()));
1261 NonVirtualAlignment = Alignment;
1263 // Lay out the virtual bases and add the primary virtual base offsets.
1264 LayoutVirtualBases(RD, RD);
1266 VisitedVirtualBases.clear();
1268 // Finally, round the size of the total struct up to the alignment of the
1273 // Check that we have base offsets for all bases.
1274 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
1275 E = RD->bases_end(); I != E; ++I) {
1279 const CXXRecordDecl *BaseDecl =
1280 cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
1282 assert(Bases.count(BaseDecl) && "Did not find base offset!");
1285 // And all virtual bases.
1286 for (CXXRecordDecl::base_class_const_iterator I = RD->vbases_begin(),
1287 E = RD->vbases_end(); I != E; ++I) {
1288 const CXXRecordDecl *BaseDecl =
1289 cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
1291 assert(VBases.count(BaseDecl) && "Did not find base offset!");
1296 void RecordLayoutBuilder::Layout(const ObjCInterfaceDecl *D) {
1297 if (ObjCInterfaceDecl *SD = D->getSuperClass()) {
1298 const ASTRecordLayout &SL = Context.getASTObjCInterfaceLayout(SD);
1300 UpdateAlignment(SL.getAlignment());
1302 // We start laying out ivars not at the end of the superclass
1303 // structure, but at the next byte following the last field.
1304 setSize(SL.getDataSize());
1305 setDataSize(getSize());
1308 InitializeLayout(D);
1309 // Layout each ivar sequentially.
1310 for (const ObjCIvarDecl *IVD = D->all_declared_ivar_begin(); IVD;
1311 IVD = IVD->getNextIvar())
1314 // Finally, round the size of the total struct up to the alignment of the
1319 void RecordLayoutBuilder::LayoutFields(const RecordDecl *D) {
1320 // Layout each field, for now, just sequentially, respecting alignment. In
1321 // the future, this will need to be tweakable by targets.
1322 const FieldDecl *LastFD = 0;
1323 ZeroLengthBitfield = 0;
1324 unsigned RemainingInAlignment = 0;
1325 for (RecordDecl::field_iterator Field = D->field_begin(),
1326 FieldEnd = D->field_end(); Field != FieldEnd; ++Field) {
1328 FieldDecl *FD = (*Field);
1329 if (Context.ZeroBitfieldFollowsBitfield(FD, LastFD))
1330 ZeroLengthBitfield = FD;
1331 // Zero-length bitfields following non-bitfield members are
1333 else if (Context.ZeroBitfieldFollowsNonBitfield(FD, LastFD))
1335 // FIXME. streamline these conditions into a simple one.
1336 else if (Context.BitfieldFollowsBitfield(FD, LastFD) ||
1337 Context.BitfieldFollowsNonBitfield(FD, LastFD) ||
1338 Context.NonBitfieldFollowsBitfield(FD, LastFD)) {
1339 // 1) Adjacent bit fields are packed into the same 1-, 2-, or
1340 // 4-byte allocation unit if the integral types are the same
1341 // size and if the next bit field fits into the current
1342 // allocation unit without crossing the boundary imposed by the
1343 // common alignment requirements of the bit fields.
1344 // 2) Establish a new alignment for a bitfield following
1345 // a non-bitfield if size of their types differ.
1346 // 3) Establish a new alignment for a non-bitfield following
1347 // a bitfield if size of their types differ.
1348 std::pair<uint64_t, unsigned> FieldInfo =
1349 Context.getTypeInfo(FD->getType());
1350 uint64_t TypeSize = FieldInfo.first;
1351 unsigned FieldAlign = FieldInfo.second;
1352 // This check is needed for 'long long' in -m32 mode.
1353 if (TypeSize > FieldAlign)
1354 FieldAlign = TypeSize;
1355 FieldInfo = Context.getTypeInfo(LastFD->getType());
1356 uint64_t TypeSizeLastFD = FieldInfo.first;
1357 unsigned FieldAlignLastFD = FieldInfo.second;
1358 // This check is needed for 'long long' in -m32 mode.
1359 if (TypeSizeLastFD > FieldAlignLastFD)
1360 FieldAlignLastFD = TypeSizeLastFD;
1362 if (TypeSizeLastFD != TypeSize) {
1363 if (RemainingInAlignment &&
1364 LastFD && LastFD->isBitField() &&
1365 LastFD->getBitWidthValue(Context)) {
1366 // If previous field was a bitfield with some remaining unfilled
1367 // bits, pad the field so current field starts on its type boundary.
1368 uint64_t FieldOffset =
1369 getDataSizeInBits() - UnfilledBitsInLastByte;
1370 uint64_t NewSizeInBits = RemainingInAlignment + FieldOffset;
1371 setDataSize(llvm::RoundUpToAlignment(NewSizeInBits,
1372 Context.getTargetInfo().getCharAlign()));
1373 setSize(std::max(getSizeInBits(), getDataSizeInBits()));
1374 RemainingInAlignment = 0;
1377 uint64_t UnpaddedFieldOffset =
1378 getDataSizeInBits() - UnfilledBitsInLastByte;
1379 FieldAlign = std::max(FieldAlign, FieldAlignLastFD);
1381 // The maximum field alignment overrides the aligned attribute.
1382 if (!MaxFieldAlignment.isZero()) {
1383 unsigned MaxFieldAlignmentInBits =
1384 Context.toBits(MaxFieldAlignment);
1385 FieldAlign = std::min(FieldAlign, MaxFieldAlignmentInBits);
1388 uint64_t NewSizeInBits =
1389 llvm::RoundUpToAlignment(UnpaddedFieldOffset, FieldAlign);
1390 setDataSize(llvm::RoundUpToAlignment(NewSizeInBits,
1391 Context.getTargetInfo().getCharAlign()));
1392 UnfilledBitsInLastByte = getDataSizeInBits() - NewSizeInBits;
1393 setSize(std::max(getSizeInBits(), getDataSizeInBits()));
1395 if (FD->isBitField()) {
1396 uint64_t FieldSize = FD->getBitWidthValue(Context);
1397 assert (FieldSize > 0 && "LayoutFields - ms_struct layout");
1398 if (RemainingInAlignment < FieldSize)
1399 RemainingInAlignment = TypeSize - FieldSize;
1401 RemainingInAlignment -= FieldSize;
1404 else if (FD->isBitField()) {
1405 uint64_t FieldSize = FD->getBitWidthValue(Context);
1406 std::pair<uint64_t, unsigned> FieldInfo =
1407 Context.getTypeInfo(FD->getType());
1408 uint64_t TypeSize = FieldInfo.first;
1409 RemainingInAlignment = TypeSize - FieldSize;
1413 else if (!Context.getTargetInfo().useBitFieldTypeAlignment() &&
1414 Context.getTargetInfo().useZeroLengthBitfieldAlignment()) {
1415 FieldDecl *FD = (*Field);
1416 if (FD->isBitField() && FD->getBitWidthValue(Context) == 0)
1417 ZeroLengthBitfield = FD;
1419 LayoutField(*Field);
1421 if (IsMsStruct && RemainingInAlignment &&
1422 LastFD && LastFD->isBitField() && LastFD->getBitWidthValue(Context)) {
1423 // If we ended a bitfield before the full length of the type then
1424 // pad the struct out to the full length of the last type.
1425 uint64_t FieldOffset =
1426 getDataSizeInBits() - UnfilledBitsInLastByte;
1427 uint64_t NewSizeInBits = RemainingInAlignment + FieldOffset;
1428 setDataSize(llvm::RoundUpToAlignment(NewSizeInBits,
1429 Context.getTargetInfo().getCharAlign()));
1430 setSize(std::max(getSizeInBits(), getDataSizeInBits()));
1434 void RecordLayoutBuilder::LayoutWideBitField(uint64_t FieldSize,
1437 const FieldDecl *D) {
1438 assert(Context.getLangOptions().CPlusPlus &&
1439 "Can only have wide bit-fields in C++!");
1441 // Itanium C++ ABI 2.4:
1442 // If sizeof(T)*8 < n, let T' be the largest integral POD type with
1443 // sizeof(T')*8 <= n.
1445 QualType IntegralPODTypes[] = {
1446 Context.UnsignedCharTy, Context.UnsignedShortTy, Context.UnsignedIntTy,
1447 Context.UnsignedLongTy, Context.UnsignedLongLongTy
1451 for (unsigned I = 0, E = llvm::array_lengthof(IntegralPODTypes);
1453 uint64_t Size = Context.getTypeSize(IntegralPODTypes[I]);
1455 if (Size > FieldSize)
1458 Type = IntegralPODTypes[I];
1460 assert(!Type.isNull() && "Did not find a type!");
1462 CharUnits TypeAlign = Context.getTypeAlignInChars(Type);
1464 // We're not going to use any of the unfilled bits in the last byte.
1465 UnfilledBitsInLastByte = 0;
1467 uint64_t FieldOffset;
1468 uint64_t UnpaddedFieldOffset = getDataSizeInBits() - UnfilledBitsInLastByte;
1471 setDataSize(std::max(getDataSizeInBits(), FieldSize));
1474 // The bitfield is allocated starting at the next offset aligned
1475 // appropriately for T', with length n bits.
1476 FieldOffset = llvm::RoundUpToAlignment(getDataSizeInBits(),
1477 Context.toBits(TypeAlign));
1479 uint64_t NewSizeInBits = FieldOffset + FieldSize;
1481 setDataSize(llvm::RoundUpToAlignment(NewSizeInBits,
1482 Context.getTargetInfo().getCharAlign()));
1483 UnfilledBitsInLastByte = getDataSizeInBits() - NewSizeInBits;
1486 // Place this field at the current location.
1487 FieldOffsets.push_back(FieldOffset);
1489 CheckFieldPadding(FieldOffset, UnpaddedFieldOffset, FieldOffset,
1490 Context.toBits(TypeAlign), FieldPacked, D);
1493 setSize(std::max(getSizeInBits(), getDataSizeInBits()));
1495 // Remember max struct/class alignment.
1496 UpdateAlignment(TypeAlign);
1499 void RecordLayoutBuilder::LayoutBitField(const FieldDecl *D) {
1500 bool FieldPacked = Packed || D->hasAttr<PackedAttr>();
1501 uint64_t UnpaddedFieldOffset = getDataSizeInBits() - UnfilledBitsInLastByte;
1502 uint64_t FieldOffset = IsUnion ? 0 : UnpaddedFieldOffset;
1503 uint64_t FieldSize = D->getBitWidthValue(Context);
1505 std::pair<uint64_t, unsigned> FieldInfo = Context.getTypeInfo(D->getType());
1506 uint64_t TypeSize = FieldInfo.first;
1507 unsigned FieldAlign = FieldInfo.second;
1509 // This check is needed for 'long long' in -m32 mode.
1510 if (IsMsStruct && (TypeSize > FieldAlign))
1511 FieldAlign = TypeSize;
1513 if (ZeroLengthBitfield) {
1514 std::pair<uint64_t, unsigned> FieldInfo;
1515 unsigned ZeroLengthBitfieldAlignment;
1517 // If a zero-length bitfield is inserted after a bitfield,
1518 // and the alignment of the zero-length bitfield is
1519 // greater than the member that follows it, `bar', `bar'
1520 // will be aligned as the type of the zero-length bitfield.
1521 if (ZeroLengthBitfield != D) {
1522 FieldInfo = Context.getTypeInfo(ZeroLengthBitfield->getType());
1523 ZeroLengthBitfieldAlignment = FieldInfo.second;
1524 // Ignore alignment of subsequent zero-length bitfields.
1525 if ((ZeroLengthBitfieldAlignment > FieldAlign) || (FieldSize == 0))
1526 FieldAlign = ZeroLengthBitfieldAlignment;
1528 ZeroLengthBitfield = 0;
1531 // The alignment of a zero-length bitfield affects the alignment
1532 // of the next member. The alignment is the max of the zero
1533 // length bitfield's alignment and a target specific fixed value.
1534 unsigned ZeroLengthBitfieldBoundary =
1535 Context.getTargetInfo().getZeroLengthBitfieldBoundary();
1536 if (ZeroLengthBitfieldBoundary > FieldAlign)
1537 FieldAlign = ZeroLengthBitfieldBoundary;
1541 if (FieldSize > TypeSize) {
1542 LayoutWideBitField(FieldSize, TypeSize, FieldPacked, D);
1546 // The align if the field is not packed. This is to check if the attribute
1547 // was unnecessary (-Wpacked).
1548 unsigned UnpackedFieldAlign = FieldAlign;
1549 uint64_t UnpackedFieldOffset = FieldOffset;
1550 if (!Context.getTargetInfo().useBitFieldTypeAlignment() && !ZeroLengthBitfield)
1551 UnpackedFieldAlign = 1;
1554 (!Context.getTargetInfo().useBitFieldTypeAlignment() && !ZeroLengthBitfield))
1556 FieldAlign = std::max(FieldAlign, D->getMaxAlignment());
1557 UnpackedFieldAlign = std::max(UnpackedFieldAlign, D->getMaxAlignment());
1559 // The maximum field alignment overrides the aligned attribute.
1560 if (!MaxFieldAlignment.isZero()) {
1561 unsigned MaxFieldAlignmentInBits = Context.toBits(MaxFieldAlignment);
1562 FieldAlign = std::min(FieldAlign, MaxFieldAlignmentInBits);
1563 UnpackedFieldAlign = std::min(UnpackedFieldAlign, MaxFieldAlignmentInBits);
1566 // Check if we need to add padding to give the field the correct alignment.
1567 if (FieldSize == 0 || (FieldOffset & (FieldAlign-1)) + FieldSize > TypeSize)
1568 FieldOffset = llvm::RoundUpToAlignment(FieldOffset, FieldAlign);
1570 if (FieldSize == 0 ||
1571 (UnpackedFieldOffset & (UnpackedFieldAlign-1)) + FieldSize > TypeSize)
1572 UnpackedFieldOffset = llvm::RoundUpToAlignment(UnpackedFieldOffset,
1573 UnpackedFieldAlign);
1575 // Padding members don't affect overall alignment, unless zero length bitfield
1576 // alignment is enabled.
1577 if (!D->getIdentifier() && !Context.getTargetInfo().useZeroLengthBitfieldAlignment())
1578 FieldAlign = UnpackedFieldAlign = 1;
1581 ZeroLengthBitfield = 0;
1583 // Place this field at the current location.
1584 FieldOffsets.push_back(FieldOffset);
1586 CheckFieldPadding(FieldOffset, UnpaddedFieldOffset, UnpackedFieldOffset,
1587 UnpackedFieldAlign, FieldPacked, D);
1589 // Update DataSize to include the last byte containing (part of) the bitfield.
1591 // FIXME: I think FieldSize should be TypeSize here.
1592 setDataSize(std::max(getDataSizeInBits(), FieldSize));
1594 uint64_t NewSizeInBits = FieldOffset + FieldSize;
1596 setDataSize(llvm::RoundUpToAlignment(NewSizeInBits,
1597 Context.getTargetInfo().getCharAlign()));
1598 UnfilledBitsInLastByte = getDataSizeInBits() - NewSizeInBits;
1602 setSize(std::max(getSizeInBits(), getDataSizeInBits()));
1604 // Remember max struct/class alignment.
1605 UpdateAlignment(Context.toCharUnitsFromBits(FieldAlign),
1606 Context.toCharUnitsFromBits(UnpackedFieldAlign));
1609 void RecordLayoutBuilder::LayoutField(const FieldDecl *D) {
1610 if (D->isBitField()) {
1615 uint64_t UnpaddedFieldOffset = getDataSizeInBits() - UnfilledBitsInLastByte;
1617 // Reset the unfilled bits.
1618 UnfilledBitsInLastByte = 0;
1620 bool FieldPacked = Packed || D->hasAttr<PackedAttr>();
1621 CharUnits FieldOffset =
1622 IsUnion ? CharUnits::Zero() : getDataSize();
1623 CharUnits FieldSize;
1624 CharUnits FieldAlign;
1626 if (D->getType()->isIncompleteArrayType()) {
1627 // This is a flexible array member; we can't directly
1628 // query getTypeInfo about these, so we figure it out here.
1629 // Flexible array members don't have any size, but they
1630 // have to be aligned appropriately for their element type.
1631 FieldSize = CharUnits::Zero();
1632 const ArrayType* ATy = Context.getAsArrayType(D->getType());
1633 FieldAlign = Context.getTypeAlignInChars(ATy->getElementType());
1634 } else if (const ReferenceType *RT = D->getType()->getAs<ReferenceType>()) {
1635 unsigned AS = RT->getPointeeType().getAddressSpace();
1637 Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(AS));
1639 Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerAlign(AS));
1641 std::pair<CharUnits, CharUnits> FieldInfo =
1642 Context.getTypeInfoInChars(D->getType());
1643 FieldSize = FieldInfo.first;
1644 FieldAlign = FieldInfo.second;
1646 if (ZeroLengthBitfield) {
1647 CharUnits ZeroLengthBitfieldBoundary =
1648 Context.toCharUnitsFromBits(
1649 Context.getTargetInfo().getZeroLengthBitfieldBoundary());
1650 if (ZeroLengthBitfieldBoundary == CharUnits::Zero()) {
1651 // If a zero-length bitfield is inserted after a bitfield,
1652 // and the alignment of the zero-length bitfield is
1653 // greater than the member that follows it, `bar', `bar'
1654 // will be aligned as the type of the zero-length bitfield.
1655 std::pair<CharUnits, CharUnits> FieldInfo =
1656 Context.getTypeInfoInChars(ZeroLengthBitfield->getType());
1657 CharUnits ZeroLengthBitfieldAlignment = FieldInfo.second;
1658 if (ZeroLengthBitfieldAlignment > FieldAlign)
1659 FieldAlign = ZeroLengthBitfieldAlignment;
1660 } else if (ZeroLengthBitfieldBoundary > FieldAlign) {
1661 // Align 'bar' based on a fixed alignment specified by the target.
1662 assert(Context.getTargetInfo().useZeroLengthBitfieldAlignment() &&
1663 "ZeroLengthBitfieldBoundary should only be used in conjunction"
1664 " with useZeroLengthBitfieldAlignment.");
1665 FieldAlign = ZeroLengthBitfieldBoundary;
1667 ZeroLengthBitfield = 0;
1670 if (Context.getLangOptions().MSBitfields || IsMsStruct) {
1671 // If MS bitfield layout is required, figure out what type is being
1672 // laid out and align the field to the width of that type.
1674 // Resolve all typedefs down to their base type and round up the field
1675 // alignment if necessary.
1676 QualType T = Context.getBaseElementType(D->getType());
1677 if (const BuiltinType *BTy = T->getAs<BuiltinType>()) {
1678 CharUnits TypeSize = Context.getTypeSizeInChars(BTy);
1679 if (TypeSize > FieldAlign)
1680 FieldAlign = TypeSize;
1685 // The align if the field is not packed. This is to check if the attribute
1686 // was unnecessary (-Wpacked).
1687 CharUnits UnpackedFieldAlign = FieldAlign;
1688 CharUnits UnpackedFieldOffset = FieldOffset;
1691 FieldAlign = CharUnits::One();
1692 CharUnits MaxAlignmentInChars =
1693 Context.toCharUnitsFromBits(D->getMaxAlignment());
1694 FieldAlign = std::max(FieldAlign, MaxAlignmentInChars);
1695 UnpackedFieldAlign = std::max(UnpackedFieldAlign, MaxAlignmentInChars);
1697 // The maximum field alignment overrides the aligned attribute.
1698 if (!MaxFieldAlignment.isZero()) {
1699 FieldAlign = std::min(FieldAlign, MaxFieldAlignment);
1700 UnpackedFieldAlign = std::min(UnpackedFieldAlign, MaxFieldAlignment);
1703 // Round up the current record size to the field's alignment boundary.
1704 FieldOffset = FieldOffset.RoundUpToAlignment(FieldAlign);
1705 UnpackedFieldOffset =
1706 UnpackedFieldOffset.RoundUpToAlignment(UnpackedFieldAlign);
1708 if (!IsUnion && EmptySubobjects) {
1709 // Check if we can place the field at this offset.
1710 while (!EmptySubobjects->CanPlaceFieldAtOffset(D, FieldOffset)) {
1711 // We couldn't place the field at the offset. Try again at a new offset.
1712 FieldOffset += FieldAlign;
1716 // Place this field at the current location.
1717 FieldOffsets.push_back(Context.toBits(FieldOffset));
1719 CheckFieldPadding(Context.toBits(FieldOffset), UnpaddedFieldOffset,
1720 Context.toBits(UnpackedFieldOffset),
1721 Context.toBits(UnpackedFieldAlign), FieldPacked, D);
1723 // Reserve space for this field.
1724 uint64_t FieldSizeInBits = Context.toBits(FieldSize);
1726 setSize(std::max(getSizeInBits(), FieldSizeInBits));
1728 setSize(FieldOffset + FieldSize);
1730 // Update the data size.
1731 setDataSize(getSizeInBits());
1733 // Remember max struct/class alignment.
1734 UpdateAlignment(FieldAlign, UnpackedFieldAlign);
1737 void RecordLayoutBuilder::MSLayoutVirtualBases(const CXXRecordDecl *RD) {
1739 if (!RD->getNumVBases())
1742 for (CXXRecordDecl::base_class_const_iterator I = RD->vbases_begin(),
1743 E = RD->vbases_end(); I != E; ++I) {
1745 const CXXRecordDecl* BaseDecl = I->getType()->getAsCXXRecordDecl();
1746 const BaseSubobjectInfo* BaseInfo = VirtualBaseInfo.lookup(BaseDecl);
1748 assert(BaseInfo && "Did not find virtual base info!");
1750 LayoutVirtualBase(BaseInfo);
1754 void RecordLayoutBuilder::MSLayout(const CXXRecordDecl *RD) {
1756 bool IsVBPtrAddedToLayout = false;
1758 InitializeLayout(RD);
1761 // If all bases are virtual and the class declares a new virtual function,
1762 // MSVC builds a vfptr.
1763 if (HasNewVirtualFunction(RD)) {
1767 VBPtrOffset = getSize();
1769 IsVBPtrAddedToLayout = true;
1771 ComputeBaseSubobjectInfo(RD);
1773 LayoutNonVirtualBases(RD);
1776 if (RD->getNumVBases() &&
1777 !IsVBPtrAddedToLayout) {
1779 VBPtrOffset = getSize();
1785 NonVirtualSize = Context.toCharUnitsFromBits(
1786 llvm::RoundUpToAlignment(getSizeInBits(),
1787 Context.getTargetInfo().getCharAlign()));
1788 NonVirtualAlignment = Alignment;
1790 if (NonVirtualSize != NonVirtualSize.RoundUpToAlignment(Alignment)) {
1791 CharUnits AlignMember =
1792 NonVirtualSize.RoundUpToAlignment(Alignment) - NonVirtualSize;
1794 setSize(getSize() + AlignMember);
1795 setDataSize(getSize());
1797 NonVirtualSize = Context.toCharUnitsFromBits(
1798 llvm::RoundUpToAlignment(getSizeInBits(),
1799 Context.getTargetInfo().getCharAlign()));
1802 MSLayoutVirtualBases(RD);
1804 VisitedVirtualBases.clear();
1806 // Finally, round the size of the total struct up to the alignment of the
1808 if (!RD->getNumVBases())
1812 // Check that we have base offsets for all bases.
1813 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
1814 E = RD->bases_end(); I != E; ++I) {
1818 const CXXRecordDecl *BaseDecl =
1819 cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
1821 assert(Bases.count(BaseDecl) && "Did not find base offset!");
1824 // And all virtual bases.
1825 for (CXXRecordDecl::base_class_const_iterator I = RD->vbases_begin(),
1826 E = RD->vbases_end(); I != E; ++I) {
1827 const CXXRecordDecl *BaseDecl =
1828 cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
1830 assert(VBases.count(BaseDecl) && "Did not find base offset!");
1835 void RecordLayoutBuilder::FinishLayout(const NamedDecl *D) {
1836 // In C++, records cannot be of size 0.
1837 if (Context.getLangOptions().CPlusPlus && getSizeInBits() == 0) {
1838 if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D)) {
1839 // Compatibility with gcc requires a class (pod or non-pod)
1840 // which is not empty but of size 0; such as having fields of
1841 // array of zero-length, remains of Size 0
1843 setSize(CharUnits::One());
1846 setSize(CharUnits::One());
1848 // Finally, round the size of the record up to the alignment of the
1850 uint64_t UnpaddedSize = getSizeInBits() - UnfilledBitsInLastByte;
1851 uint64_t UnpackedSizeInBits =
1852 llvm::RoundUpToAlignment(getSizeInBits(),
1853 Context.toBits(UnpackedAlignment));
1854 CharUnits UnpackedSize = Context.toCharUnitsFromBits(UnpackedSizeInBits);
1855 setSize(llvm::RoundUpToAlignment(getSizeInBits(), Context.toBits(Alignment)));
1857 unsigned CharBitNum = Context.getTargetInfo().getCharWidth();
1858 if (const RecordDecl *RD = dyn_cast<RecordDecl>(D)) {
1859 // Warn if padding was introduced to the struct/class/union.
1860 if (getSizeInBits() > UnpaddedSize) {
1861 unsigned PadSize = getSizeInBits() - UnpaddedSize;
1863 if (PadSize % CharBitNum == 0) {
1864 PadSize = PadSize / CharBitNum;
1867 Diag(RD->getLocation(), diag::warn_padded_struct_size)
1868 << Context.getTypeDeclType(RD)
1870 << (InBits ? 1 : 0) /*(byte|bit)*/ << (PadSize > 1); // plural or not
1873 // Warn if we packed it unnecessarily. If the alignment is 1 byte don't
1874 // bother since there won't be alignment issues.
1875 if (Packed && UnpackedAlignment > CharUnits::One() &&
1876 getSize() == UnpackedSize)
1877 Diag(D->getLocation(), diag::warn_unnecessary_packed)
1878 << Context.getTypeDeclType(RD);
1882 void RecordLayoutBuilder::UpdateAlignment(CharUnits NewAlignment,
1883 CharUnits UnpackedNewAlignment) {
1884 // The alignment is not modified when using 'mac68k' alignment.
1888 if (NewAlignment > Alignment) {
1889 assert(llvm::isPowerOf2_32(NewAlignment.getQuantity() &&
1890 "Alignment not a power of 2"));
1891 Alignment = NewAlignment;
1894 if (UnpackedNewAlignment > UnpackedAlignment) {
1895 assert(llvm::isPowerOf2_32(UnpackedNewAlignment.getQuantity() &&
1896 "Alignment not a power of 2"));
1897 UnpackedAlignment = UnpackedNewAlignment;
1901 void RecordLayoutBuilder::CheckFieldPadding(uint64_t Offset,
1902 uint64_t UnpaddedOffset,
1903 uint64_t UnpackedOffset,
1904 unsigned UnpackedAlign,
1906 const FieldDecl *D) {
1907 // We let objc ivars without warning, objc interfaces generally are not used
1908 // for padding tricks.
1909 if (isa<ObjCIvarDecl>(D))
1912 // Don't warn about structs created without a SourceLocation. This can
1913 // be done by clients of the AST, such as codegen.
1914 if (D->getLocation().isInvalid())
1917 unsigned CharBitNum = Context.getTargetInfo().getCharWidth();
1919 // Warn if padding was introduced to the struct/class.
1920 if (!IsUnion && Offset > UnpaddedOffset) {
1921 unsigned PadSize = Offset - UnpaddedOffset;
1923 if (PadSize % CharBitNum == 0) {
1924 PadSize = PadSize / CharBitNum;
1927 if (D->getIdentifier())
1928 Diag(D->getLocation(), diag::warn_padded_struct_field)
1929 << (D->getParent()->isStruct() ? 0 : 1) // struct|class
1930 << Context.getTypeDeclType(D->getParent())
1932 << (InBits ? 1 : 0) /*(byte|bit)*/ << (PadSize > 1) // plural or not
1933 << D->getIdentifier();
1935 Diag(D->getLocation(), diag::warn_padded_struct_anon_field)
1936 << (D->getParent()->isStruct() ? 0 : 1) // struct|class
1937 << Context.getTypeDeclType(D->getParent())
1939 << (InBits ? 1 : 0) /*(byte|bit)*/ << (PadSize > 1); // plural or not
1942 // Warn if we packed it unnecessarily. If the alignment is 1 byte don't
1943 // bother since there won't be alignment issues.
1944 if (isPacked && UnpackedAlign > CharBitNum && Offset == UnpackedOffset)
1945 Diag(D->getLocation(), diag::warn_unnecessary_packed)
1946 << D->getIdentifier();
1949 const CXXMethodDecl *
1950 RecordLayoutBuilder::ComputeKeyFunction(const CXXRecordDecl *RD) {
1951 // If a class isn't polymorphic it doesn't have a key function.
1952 if (!RD->isPolymorphic())
1955 // A class that is not externally visible doesn't have a key function. (Or
1956 // at least, there's no point to assigning a key function to such a class;
1957 // this doesn't affect the ABI.)
1958 if (RD->getLinkage() != ExternalLinkage)
1961 // Template instantiations don't have key functions,see Itanium C++ ABI 5.2.6.
1962 // Same behavior as GCC.
1963 TemplateSpecializationKind TSK = RD->getTemplateSpecializationKind();
1964 if (TSK == TSK_ImplicitInstantiation ||
1965 TSK == TSK_ExplicitInstantiationDefinition)
1968 for (CXXRecordDecl::method_iterator I = RD->method_begin(),
1969 E = RD->method_end(); I != E; ++I) {
1970 const CXXMethodDecl *MD = *I;
1972 if (!MD->isVirtual())
1978 // Ignore implicit member functions, they are always marked as inline, but
1979 // they don't have a body until they're defined.
1980 if (MD->isImplicit())
1983 if (MD->isInlineSpecified())
1986 if (MD->hasInlineBody())
1997 RecordLayoutBuilder::Diag(SourceLocation Loc, unsigned DiagID) {
1998 return Context.getDiagnostics().Report(Loc, DiagID);
2001 /// getASTRecordLayout - Get or compute information about the layout of the
2002 /// specified record (struct/union/class), which indicates its size and field
2003 /// position information.
2004 const ASTRecordLayout &
2005 ASTContext::getASTRecordLayout(const RecordDecl *D) const {
2006 // These asserts test different things. A record has a definition
2007 // as soon as we begin to parse the definition. That definition is
2008 // not a complete definition (which is what isDefinition() tests)
2009 // until we *finish* parsing the definition.
2010 D = D->getDefinition();
2011 assert(D && "Cannot get layout of forward declarations!");
2012 assert(D->isCompleteDefinition() && "Cannot layout type before complete!");
2014 // Look up this layout, if already laid out, return what we have.
2015 // Note that we can't save a reference to the entry because this function
2017 const ASTRecordLayout *Entry = ASTRecordLayouts[D];
2018 if (Entry) return *Entry;
2020 const ASTRecordLayout *NewEntry;
2022 if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D)) {
2023 EmptySubobjectMap EmptySubobjects(*this, RD);
2025 llvm::OwningPtr<RecordLayoutBuilder> Builder;
2026 CharUnits TargetAlign = CharUnits::One();
2028 Builder.reset(new RecordLayoutBuilder(*this,
2032 // Recover resources if we crash before exiting this method.
2033 llvm::CrashRecoveryContextCleanupRegistrar<RecordLayoutBuilder>
2034 RecordBuilderCleanup(Builder.get());
2036 Builder->Layout(RD);
2038 TargetAlign = Builder->getAligment();
2040 if (getTargetInfo().getCXXABI() == CXXABI_Microsoft &&
2041 TargetAlign.getQuantity() > 4) {
2042 // MSVC rounds the vtable pointer to the struct alignment in what must
2043 // be a multi-pass operation. For now, let the builder figure out the
2044 // alignment and recalculate the layout once its known.
2045 Builder.reset(new RecordLayoutBuilder(*this,
2049 Builder->Layout(RD);
2051 // Recover resources if we crash before exiting this method.
2052 llvm::CrashRecoveryContextCleanupRegistrar<RecordLayoutBuilder>
2053 RecordBuilderCleanup(Builder.get());
2056 // FIXME: This is not always correct. See the part about bitfields at
2057 // http://www.codesourcery.com/public/cxx-abi/abi.html#POD for more info.
2058 // FIXME: IsPODForThePurposeOfLayout should be stored in the record layout.
2059 // This does not affect the calculations of MSVC layouts
2060 bool IsPODForThePurposeOfLayout =
2061 (getTargetInfo().getCXXABI() == CXXABI_Microsoft) ||
2062 cast<CXXRecordDecl>(D)->isPOD();
2064 // FIXME: This should be done in FinalizeLayout.
2065 CharUnits DataSize =
2066 IsPODForThePurposeOfLayout ? Builder->getSize() : Builder->getDataSize();
2067 CharUnits NonVirtualSize =
2068 IsPODForThePurposeOfLayout ? DataSize : Builder->NonVirtualSize;
2071 new (*this) ASTRecordLayout(*this, Builder->getSize(),
2073 Builder->GetVBPtrOffset(),
2075 Builder->FieldOffsets.data(),
2076 Builder->FieldOffsets.size(),
2078 Builder->NonVirtualAlignment,
2079 EmptySubobjects.SizeOfLargestEmptySubobject,
2080 Builder->PrimaryBase,
2081 Builder->PrimaryBaseIsVirtual,
2082 Builder->Bases, Builder->VBases);
2084 RecordLayoutBuilder Builder(*this, /*EmptySubobjects=*/0, CharUnits::One());
2088 new (*this) ASTRecordLayout(*this, Builder.getSize(),
2091 Builder.FieldOffsets.data(),
2092 Builder.FieldOffsets.size());
2095 ASTRecordLayouts[D] = NewEntry;
2097 if (getLangOptions().DumpRecordLayouts) {
2098 llvm::errs() << "\n*** Dumping AST Record Layout\n";
2099 DumpRecordLayout(D, llvm::errs());
2105 const CXXMethodDecl *ASTContext::getKeyFunction(const CXXRecordDecl *RD) {
2106 RD = cast<CXXRecordDecl>(RD->getDefinition());
2107 assert(RD && "Cannot get key function for forward declarations!");
2109 const CXXMethodDecl *&Entry = KeyFunctions[RD];
2111 Entry = RecordLayoutBuilder::ComputeKeyFunction(RD);
2116 /// getObjCLayout - Get or compute information about the layout of the
2117 /// given interface.
2119 /// \param Impl - If given, also include the layout of the interface's
2120 /// implementation. This may differ by including synthesized ivars.
2121 const ASTRecordLayout &
2122 ASTContext::getObjCLayout(const ObjCInterfaceDecl *D,
2123 const ObjCImplementationDecl *Impl) const {
2124 assert(!D->isForwardDecl() && "Invalid interface decl!");
2126 // Look up this layout, if already laid out, return what we have.
2127 ObjCContainerDecl *Key =
2128 Impl ? (ObjCContainerDecl*) Impl : (ObjCContainerDecl*) D;
2129 if (const ASTRecordLayout *Entry = ObjCLayouts[Key])
2132 // Add in synthesized ivar count if laying out an implementation.
2134 unsigned SynthCount = CountNonClassIvars(D);
2135 // If there aren't any sythesized ivars then reuse the interface
2136 // entry. Note we can't cache this because we simply free all
2137 // entries later; however we shouldn't look up implementations
2139 if (SynthCount == 0)
2140 return getObjCLayout(D, 0);
2143 RecordLayoutBuilder Builder(*this, /*EmptySubobjects=*/0, CharUnits::One());
2146 const ASTRecordLayout *NewEntry =
2147 new (*this) ASTRecordLayout(*this, Builder.getSize(),
2149 Builder.getDataSize(),
2150 Builder.FieldOffsets.data(),
2151 Builder.FieldOffsets.size());
2153 ObjCLayouts[Key] = NewEntry;
2158 static void PrintOffset(raw_ostream &OS,
2159 CharUnits Offset, unsigned IndentLevel) {
2160 OS << llvm::format("%4d | ", Offset.getQuantity());
2161 OS.indent(IndentLevel * 2);
2164 static void DumpCXXRecordLayout(raw_ostream &OS,
2165 const CXXRecordDecl *RD, const ASTContext &C,
2167 unsigned IndentLevel,
2168 const char* Description,
2169 bool IncludeVirtualBases) {
2170 const ASTRecordLayout &Layout = C.getASTRecordLayout(RD);
2172 PrintOffset(OS, Offset, IndentLevel);
2173 OS << C.getTypeDeclType(const_cast<CXXRecordDecl *>(RD)).getAsString();
2175 OS << ' ' << Description;
2182 const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
2183 bool HasVbptr = Layout.getVBPtrOffset() != CharUnits::fromQuantity(-1);
2186 if (RD->isDynamicClass() && !PrimaryBase) {
2187 PrintOffset(OS, Offset, IndentLevel);
2188 OS << '(' << *RD << " vtable pointer)\n";
2191 if (HasVbptr && !PrimaryBase) {
2192 PrintOffset(OS, Offset + Layout.getVBPtrOffset(), IndentLevel);
2193 OS << '(' << *RD << " vbtable pointer)\n";
2195 // one vbtable per class
2199 // Dump (non-virtual) bases
2200 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
2201 E = RD->bases_end(); I != E; ++I) {
2202 assert(!I->getType()->isDependentType() &&
2203 "Cannot layout class with dependent bases.");
2207 const CXXRecordDecl *Base =
2208 cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
2210 CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base);
2212 DumpCXXRecordLayout(OS, Base, C, BaseOffset, IndentLevel,
2213 Base == PrimaryBase ? "(primary base)" : "(base)",
2214 /*IncludeVirtualBases=*/false);
2218 PrintOffset(OS, Offset + Layout.getVBPtrOffset(), IndentLevel);
2219 OS << '(' << *RD << " vbtable pointer)\n";
2223 uint64_t FieldNo = 0;
2224 for (CXXRecordDecl::field_iterator I = RD->field_begin(),
2225 E = RD->field_end(); I != E; ++I, ++FieldNo) {
2226 const FieldDecl *Field = *I;
2227 CharUnits FieldOffset = Offset +
2228 C.toCharUnitsFromBits(Layout.getFieldOffset(FieldNo));
2230 if (const RecordType *RT = Field->getType()->getAs<RecordType>()) {
2231 if (const CXXRecordDecl *D = dyn_cast<CXXRecordDecl>(RT->getDecl())) {
2232 DumpCXXRecordLayout(OS, D, C, FieldOffset, IndentLevel,
2233 Field->getName().data(),
2234 /*IncludeVirtualBases=*/true);
2239 PrintOffset(OS, FieldOffset, IndentLevel);
2240 OS << Field->getType().getAsString() << ' ' << *Field << '\n';
2243 if (!IncludeVirtualBases)
2246 // Dump virtual bases.
2247 for (CXXRecordDecl::base_class_const_iterator I = RD->vbases_begin(),
2248 E = RD->vbases_end(); I != E; ++I) {
2249 assert(I->isVirtual() && "Found non-virtual class!");
2250 const CXXRecordDecl *VBase =
2251 cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
2253 CharUnits VBaseOffset = Offset + Layout.getVBaseClassOffset(VBase);
2254 DumpCXXRecordLayout(OS, VBase, C, VBaseOffset, IndentLevel,
2255 VBase == PrimaryBase ?
2256 "(primary virtual base)" : "(virtual base)",
2257 /*IncludeVirtualBases=*/false);
2260 OS << " sizeof=" << Layout.getSize().getQuantity();
2261 OS << ", dsize=" << Layout.getDataSize().getQuantity();
2262 OS << ", align=" << Layout.getAlignment().getQuantity() << '\n';
2263 OS << " nvsize=" << Layout.getNonVirtualSize().getQuantity();
2264 OS << ", nvalign=" << Layout.getNonVirtualAlign().getQuantity() << '\n';
2268 void ASTContext::DumpRecordLayout(const RecordDecl *RD,
2269 raw_ostream &OS) const {
2270 const ASTRecordLayout &Info = getASTRecordLayout(RD);
2272 if (const CXXRecordDecl *CXXRD = dyn_cast<CXXRecordDecl>(RD))
2273 return DumpCXXRecordLayout(OS, CXXRD, *this, CharUnits(), 0, 0,
2274 /*IncludeVirtualBases=*/true);
2276 OS << "Type: " << getTypeDeclType(RD).getAsString() << "\n";
2280 OS << "<ASTRecordLayout\n";
2281 OS << " Size:" << toBits(Info.getSize()) << "\n";
2282 OS << " DataSize:" << toBits(Info.getDataSize()) << "\n";
2283 OS << " Alignment:" << toBits(Info.getAlignment()) << "\n";
2284 OS << " FieldOffsets: [";
2285 for (unsigned i = 0, e = Info.getFieldCount(); i != e; ++i) {
2287 OS << Info.getFieldOffset(i);