/usr/src/gnu/usr.bin/clang/libclangAST/../../../llvm/clang/lib/AST/RecordLayoutBuilder.cpp

Bug Summary

File:	src/gnu/usr.bin/clang/libclangAST/../../../llvm/clang/lib/AST/RecordLayoutBuilder.cpp
Warning:	line 1181, column 10 Called C++ object pointer is null
Annotated Source Code

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1//=== RecordLayoutBuilder.cpp - Helper class for building record layouts ---==//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//

9#include "clang/AST/ASTContext.h"
10#include "clang/AST/ASTDiagnostic.h"
11#include "clang/AST/Attr.h"
12#include "clang/AST/CXXInheritance.h"
13#include "clang/AST/Decl.h"
14#include "clang/AST/DeclCXX.h"
15#include "clang/AST/DeclObjC.h"
16#include "clang/AST/Expr.h"
17#include "clang/AST/VTableBuilder.h"
18#include "clang/AST/RecordLayout.h"
19#include "clang/Basic/TargetInfo.h"
20#include "llvm/ADT/SmallSet.h"
21#include "llvm/Support/Format.h"
22#include "llvm/Support/MathExtras.h"

24using namespace clang;

26namespace {

28/// BaseSubobjectInfo - Represents a single base subobject in a complete class.
29/// For a class hierarchy like
30///
31/// class A { };
32/// class B : A { };
33/// class C : A, B { };
34///
35/// The BaseSubobjectInfo graph for C will have three BaseSubobjectInfo
36/// instances, one for B and two for A.
37///
38/// If a base is virtual, it will only have one BaseSubobjectInfo allocated.
39struct BaseSubobjectInfo {
/// Class - The class for this base info.
const CXXRecordDecl *Class;

/// IsVirtual - Whether the BaseInfo represents a virtual base or not.
bool IsVirtual;

/// Bases - Information about the base subobjects.
SmallVector<BaseSubobjectInfo*, 4> Bases;

/// PrimaryVirtualBaseInfo - Holds the base info for the primary virtual base
/// of this base info (if one exists).
BaseSubobjectInfo *PrimaryVirtualBaseInfo;

// FIXME: Document.
const BaseSubobjectInfo *Derived;
55};

57/// Externally provided layout. Typically used when the AST source, such
58/// as DWARF, lacks all the information that was available at compile time, such
59/// as alignment attributes on fields and pragmas in effect.
60struct ExternalLayout {
ExternalLayout() : Size(0), Align(0) {}

/// Overall record size in bits.
uint64_t Size;

/// Overall record alignment in bits.
uint64_t Align;

/// Record field offsets in bits.
llvm::DenseMap<const FieldDecl *, uint64_t> FieldOffsets;

/// Direct, non-virtual base offsets.
llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsets;

/// Virtual base offsets.
llvm::DenseMap<const CXXRecordDecl *, CharUnits> VirtualBaseOffsets;

/// Get the offset of the given field. The external source must provide
/// entries for all fields in the record.
uint64_t getExternalFieldOffset(const FieldDecl *FD) {
  assert(FieldOffsets.count(FD) &&((void)0)
         "Field does not have an external offset")((void)0);
  return FieldOffsets[FD];
}

bool getExternalNVBaseOffset(const CXXRecordDecl *RD, CharUnits &BaseOffset) {
  auto Known = BaseOffsets.find(RD);
  if (Known == BaseOffsets.end())
    return false;
  BaseOffset = Known->second;
  return true;
}

bool getExternalVBaseOffset(const CXXRecordDecl *RD, CharUnits &BaseOffset) {
  auto Known = VirtualBaseOffsets.find(RD);
  if (Known == VirtualBaseOffsets.end())
    return false;
  BaseOffset = Known->second;
  return true;
}
101};

103/// EmptySubobjectMap - Keeps track of which empty subobjects exist at different
104/// offsets while laying out a C++ class.
105class EmptySubobjectMap {
const ASTContext &Context;
uint64_t CharWidth;

/// Class - The class whose empty entries we're keeping track of.
const CXXRecordDecl *Class;

/// EmptyClassOffsets - A map from offsets to empty record decls.
typedef llvm::TinyPtrVector<const CXXRecordDecl *> ClassVectorTy;
typedef llvm::DenseMap<CharUnits, ClassVectorTy> EmptyClassOffsetsMapTy;
EmptyClassOffsetsMapTy EmptyClassOffsets;

/// MaxEmptyClassOffset - The highest offset known to contain an empty
/// base subobject.
CharUnits MaxEmptyClassOffset;

/// ComputeEmptySubobjectSizes - Compute the size of the largest base or
/// member subobject that is empty.
void ComputeEmptySubobjectSizes();

void AddSubobjectAtOffset(const CXXRecordDecl *RD, CharUnits Offset);

void UpdateEmptyBaseSubobjects(const BaseSubobjectInfo *Info,
                               CharUnits Offset, bool PlacingEmptyBase);

void UpdateEmptyFieldSubobjects(const CXXRecordDecl *RD,
                                const CXXRecordDecl *Class, CharUnits Offset,
                                bool PlacingOverlappingField);
void UpdateEmptyFieldSubobjects(const FieldDecl *FD, CharUnits Offset,
                                bool PlacingOverlappingField);

/// AnyEmptySubobjectsBeyondOffset - Returns whether there are any empty
/// subobjects beyond the given offset.
bool AnyEmptySubobjectsBeyondOffset(CharUnits Offset) const {
  return Offset <= MaxEmptyClassOffset;
}

CharUnits
getFieldOffset(const ASTRecordLayout &Layout, unsigned FieldNo) const {
  uint64_t FieldOffset = Layout.getFieldOffset(FieldNo);
  assert(FieldOffset % CharWidth == 0 &&((void)0)
         "Field offset not at char boundary!")((void)0);

  return Context.toCharUnitsFromBits(FieldOffset);
}

151protected:
bool CanPlaceSubobjectAtOffset(const CXXRecordDecl *RD,
                               CharUnits Offset) const;

bool CanPlaceBaseSubobjectAtOffset(const BaseSubobjectInfo *Info,
                                   CharUnits Offset);

bool CanPlaceFieldSubobjectAtOffset(const CXXRecordDecl *RD,
                                    const CXXRecordDecl *Class,
                                    CharUnits Offset) const;
bool CanPlaceFieldSubobjectAtOffset(const FieldDecl *FD,
                                    CharUnits Offset) const;

164public:
/// This holds the size of the largest empty subobject (either a base
/// or a member). Will be zero if the record being built doesn't contain
/// any empty classes.
CharUnits SizeOfLargestEmptySubobject;

EmptySubobjectMap(const ASTContext &Context, const CXXRecordDecl *Class)
: Context(Context), CharWidth(Context.getCharWidth()), Class(Class) {
    ComputeEmptySubobjectSizes();
}

/// CanPlaceBaseAtOffset - Return whether the given base class can be placed
/// at the given offset.
/// Returns false if placing the record will result in two components
/// (direct or indirect) of the same type having the same offset.
bool CanPlaceBaseAtOffset(const BaseSubobjectInfo *Info,
                          CharUnits Offset);

/// CanPlaceFieldAtOffset - Return whether a field can be placed at the given
/// offset.
bool CanPlaceFieldAtOffset(const FieldDecl *FD, CharUnits Offset);
185};

187void EmptySubobjectMap::ComputeEmptySubobjectSizes() {
// Check the bases.
for (const CXXBaseSpecifier &Base : Class->bases()) {
  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();

  CharUnits EmptySize;
  const ASTRecordLayout &Layout = Context.getASTRecordLayout(BaseDecl);
  if (BaseDecl->isEmpty()) {
    // If the class decl is empty, get its size.
    EmptySize = Layout.getSize();
  } else {
    // Otherwise, we get the largest empty subobject for the decl.
    EmptySize = Layout.getSizeOfLargestEmptySubobject();
  }

  if (EmptySize > SizeOfLargestEmptySubobject)
    SizeOfLargestEmptySubobject = EmptySize;
}

// Check the fields.
for (const FieldDecl *FD : Class->fields()) {
  const RecordType *RT =
      Context.getBaseElementType(FD->getType())->getAs<RecordType>();

  // We only care about record types.
  if (!RT)
    continue;

  CharUnits EmptySize;
  const CXXRecordDecl *MemberDecl = RT->getAsCXXRecordDecl();
  const ASTRecordLayout &Layout = Context.getASTRecordLayout(MemberDecl);
  if (MemberDecl->isEmpty()) {
    // If the class decl is empty, get its size.
    EmptySize = Layout.getSize();
  } else {
    // Otherwise, we get the largest empty subobject for the decl.
    EmptySize = Layout.getSizeOfLargestEmptySubobject();
  }

  if (EmptySize > SizeOfLargestEmptySubobject)
    SizeOfLargestEmptySubobject = EmptySize;
}
229}

231bool
232EmptySubobjectMap::CanPlaceSubobjectAtOffset(const CXXRecordDecl *RD,
                                           CharUnits Offset) const {
// We only need to check empty bases.
if (!RD->isEmpty())
  return true;

EmptyClassOffsetsMapTy::const_iterator I = EmptyClassOffsets.find(Offset);
if (I == EmptyClassOffsets.end())
  return true;

const ClassVectorTy &Classes = I->second;
if (llvm::find(Classes, RD) == Classes.end())
  return true;

// There is already an empty class of the same type at this offset.
return false;
248}

250void EmptySubobjectMap::AddSubobjectAtOffset(const CXXRecordDecl *RD,
                                           CharUnits Offset) {
// We only care about empty bases.
if (!RD->isEmpty())
  return;

// If we have empty structures inside a union, we can assign both
// the same offset. Just avoid pushing them twice in the list.
ClassVectorTy &Classes = EmptyClassOffsets[Offset];
if (llvm::is_contained(Classes, RD))
  return;

Classes.push_back(RD);

// Update the empty class offset.
if (Offset > MaxEmptyClassOffset)
  MaxEmptyClassOffset = Offset;
267}

269bool
270EmptySubobjectMap::CanPlaceBaseSubobjectAtOffset(const BaseSubobjectInfo *Info,
                                               CharUnits Offset) {
// We don't have to keep looking past the maximum offset that's known to
// contain an empty class.
if (!AnyEmptySubobjectsBeyondOffset(Offset))
  return true;

if (!CanPlaceSubobjectAtOffset(Info->Class, Offset))
  return false;

// Traverse all non-virtual bases.
const ASTRecordLayout &Layout = Context.getASTRecordLayout(Info->Class);
for (const BaseSubobjectInfo *Base : Info->Bases) {
  if (Base->IsVirtual)
    continue;

  CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base->Class);

  if (!CanPlaceBaseSubobjectAtOffset(Base, BaseOffset))
    return false;
}

if (Info->PrimaryVirtualBaseInfo) {
  BaseSubobjectInfo *PrimaryVirtualBaseInfo = Info->PrimaryVirtualBaseInfo;

  if (Info == PrimaryVirtualBaseInfo->Derived) {
    if (!CanPlaceBaseSubobjectAtOffset(PrimaryVirtualBaseInfo, Offset))
      return false;
  }
}

// Traverse all member variables.
unsigned FieldNo = 0;
for (CXXRecordDecl::field_iterator I = Info->Class->field_begin(),
     E = Info->Class->field_end(); I != E; ++I, ++FieldNo) {
  if (I->isBitField())
    continue;

  CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
  if (!CanPlaceFieldSubobjectAtOffset(*I, FieldOffset))
    return false;
}

return true;
314}

316void EmptySubobjectMap::UpdateEmptyBaseSubobjects(const BaseSubobjectInfo *Info,
                                                CharUnits Offset,
                                                bool PlacingEmptyBase) {
if (!PlacingEmptyBase && Offset >= SizeOfLargestEmptySubobject) {
  // We know that the only empty subobjects that can conflict with empty
  // subobject of non-empty bases, are empty bases that can be placed at
  // offset zero. Because of this, we only need to keep track of empty base
  // subobjects with offsets less than the size of the largest empty
  // subobject for our class.
  return;
}

AddSubobjectAtOffset(Info->Class, Offset);

// Traverse all non-virtual bases.
const ASTRecordLayout &Layout = Context.getASTRecordLayout(Info->Class);
for (const BaseSubobjectInfo *Base : Info->Bases) {
  if (Base->IsVirtual)
    continue;

  CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base->Class);
  UpdateEmptyBaseSubobjects(Base, BaseOffset, PlacingEmptyBase);
}

if (Info->PrimaryVirtualBaseInfo) {
  BaseSubobjectInfo *PrimaryVirtualBaseInfo = Info->PrimaryVirtualBaseInfo;

  if (Info == PrimaryVirtualBaseInfo->Derived)
    UpdateEmptyBaseSubobjects(PrimaryVirtualBaseInfo, Offset,
                              PlacingEmptyBase);
}

// Traverse all member variables.
unsigned FieldNo = 0;
for (CXXRecordDecl::field_iterator I = Info->Class->field_begin(),
     E = Info->Class->field_end(); I != E; ++I, ++FieldNo) {
  if (I->isBitField())
    continue;

  CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
  UpdateEmptyFieldSubobjects(*I, FieldOffset, PlacingEmptyBase);
}
358}

360bool EmptySubobjectMap::CanPlaceBaseAtOffset(const BaseSubobjectInfo *Info,
                                           CharUnits Offset) {
// If we know this class doesn't have any empty subobjects we don't need to
// bother checking.
if (SizeOfLargestEmptySubobject.isZero())
  return true;

if (!CanPlaceBaseSubobjectAtOffset(Info, Offset))
  return false;

// We are able to place the base at this offset. Make sure to update the
// empty base subobject map.
UpdateEmptyBaseSubobjects(Info, Offset, Info->Class->isEmpty());
return true;
374}

376bool
377EmptySubobjectMap::CanPlaceFieldSubobjectAtOffset(const CXXRecordDecl *RD,
                                                const CXXRecordDecl *Class,
                                                CharUnits Offset) const {
// We don't have to keep looking past the maximum offset that's known to
// contain an empty class.
if (!AnyEmptySubobjectsBeyondOffset(Offset))
  return true;

if (!CanPlaceSubobjectAtOffset(RD, Offset))
  return false;

const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);

// Traverse all non-virtual bases.
for (const CXXBaseSpecifier &Base : RD->bases()) {
  if (Base.isVirtual())
    continue;

  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();

  CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(BaseDecl);
  if (!CanPlaceFieldSubobjectAtOffset(BaseDecl, Class, BaseOffset))
    return false;
}

if (RD == Class) {
  // This is the most derived class, traverse virtual bases as well.
  for (const CXXBaseSpecifier &Base : RD->vbases()) {
    const CXXRecordDecl *VBaseDecl = Base.getType()->getAsCXXRecordDecl();

    CharUnits VBaseOffset = Offset + Layout.getVBaseClassOffset(VBaseDecl);
    if (!CanPlaceFieldSubobjectAtOffset(VBaseDecl, Class, VBaseOffset))
      return false;
  }
}

// Traverse all member variables.
unsigned FieldNo = 0;
for (CXXRecordDecl::field_iterator I = RD->field_begin(), E = RD->field_end();
     I != E; ++I, ++FieldNo) {
  if (I->isBitField())
    continue;

  CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);

  if (!CanPlaceFieldSubobjectAtOffset(*I, FieldOffset))
    return false;
}

return true;
427}

429bool
430EmptySubobjectMap::CanPlaceFieldSubobjectAtOffset(const FieldDecl *FD,
                                                CharUnits Offset) const {
// We don't have to keep looking past the maximum offset that's known to
// contain an empty class.
if (!AnyEmptySubobjectsBeyondOffset(Offset))
  return true;

QualType T = FD->getType();
if (const CXXRecordDecl *RD = T->getAsCXXRecordDecl())
  return CanPlaceFieldSubobjectAtOffset(RD, RD, Offset);

// If we have an array type we need to look at every element.
if (const ConstantArrayType *AT = Context.getAsConstantArrayType(T)) {
  QualType ElemTy = Context.getBaseElementType(AT);
  const RecordType *RT = ElemTy->getAs<RecordType>();
  if (!RT)
    return true;

  const CXXRecordDecl *RD = RT->getAsCXXRecordDecl();
  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);

  uint64_t NumElements = Context.getConstantArrayElementCount(AT);
  CharUnits ElementOffset = Offset;
  for (uint64_t I = 0; I != NumElements; ++I) {
    // We don't have to keep looking past the maximum offset that's known to
    // contain an empty class.
    if (!AnyEmptySubobjectsBeyondOffset(ElementOffset))
      return true;

    if (!CanPlaceFieldSubobjectAtOffset(RD, RD, ElementOffset))
      return false;

    ElementOffset += Layout.getSize();
  }
}

return true;
467}

469bool
470EmptySubobjectMap::CanPlaceFieldAtOffset(const FieldDecl *FD,
                                       CharUnits Offset) {
if (!CanPlaceFieldSubobjectAtOffset(FD, Offset))
  return false;

// We are able to place the member variable at this offset.
// Make sure to update the empty field subobject map.
UpdateEmptyFieldSubobjects(FD, Offset, FD->hasAttr<NoUniqueAddressAttr>());
return true;
479}

481void EmptySubobjectMap::UpdateEmptyFieldSubobjects(
  const CXXRecordDecl *RD, const CXXRecordDecl *Class, CharUnits Offset,
  bool PlacingOverlappingField) {
// We know that the only empty subobjects that can conflict with empty
// field subobjects are subobjects of empty bases and potentially-overlapping
// fields that can be placed at offset zero. Because of this, we only need to
// keep track of empty field subobjects with offsets less than the size of
// the largest empty subobject for our class.
//
// (Proof: we will only consider placing a subobject at offset zero or at
// >= the current dsize. The only cases where the earlier subobject can be
// placed beyond the end of dsize is if it's an empty base or a
// potentially-overlapping field.)
if (!PlacingOverlappingField && Offset >= SizeOfLargestEmptySubobject)
  return;

AddSubobjectAtOffset(RD, Offset);

const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);

// Traverse all non-virtual bases.
for (const CXXBaseSpecifier &Base : RD->bases()) {
  if (Base.isVirtual())
    continue;

  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();

  CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(BaseDecl);
  UpdateEmptyFieldSubobjects(BaseDecl, Class, BaseOffset,
                             PlacingOverlappingField);
}

if (RD == Class) {
  // This is the most derived class, traverse virtual bases as well.
  for (const CXXBaseSpecifier &Base : RD->vbases()) {
    const CXXRecordDecl *VBaseDecl = Base.getType()->getAsCXXRecordDecl();

    CharUnits VBaseOffset = Offset + Layout.getVBaseClassOffset(VBaseDecl);
    UpdateEmptyFieldSubobjects(VBaseDecl, Class, VBaseOffset,
                               PlacingOverlappingField);
  }
}

// Traverse all member variables.
unsigned FieldNo = 0;
for (CXXRecordDecl::field_iterator I = RD->field_begin(), E = RD->field_end();
     I != E; ++I, ++FieldNo) {
  if (I->isBitField())
    continue;

  CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);

  UpdateEmptyFieldSubobjects(*I, FieldOffset, PlacingOverlappingField);
}
535}

537void EmptySubobjectMap::UpdateEmptyFieldSubobjects(
  const FieldDecl *FD, CharUnits Offset, bool PlacingOverlappingField) {
QualType T = FD->getType();
if (const CXXRecordDecl *RD = T->getAsCXXRecordDecl()) {
  UpdateEmptyFieldSubobjects(RD, RD, Offset, PlacingOverlappingField);
  return;
}

// If we have an array type we need to update every element.
if (const ConstantArrayType *AT = Context.getAsConstantArrayType(T)) {
  QualType ElemTy = Context.getBaseElementType(AT);
  const RecordType *RT = ElemTy->getAs<RecordType>();
  if (!RT)
    return;

  const CXXRecordDecl *RD = RT->getAsCXXRecordDecl();
  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);

  uint64_t NumElements = Context.getConstantArrayElementCount(AT);
  CharUnits ElementOffset = Offset;

  for (uint64_t I = 0; I != NumElements; ++I) {
    // We know that the only empty subobjects that can conflict with empty
    // field subobjects are subobjects of empty bases that can be placed at
    // offset zero. Because of this, we only need to keep track of empty field
    // subobjects with offsets less than the size of the largest empty
    // subobject for our class.
    if (!PlacingOverlappingField &&
        ElementOffset >= SizeOfLargestEmptySubobject)
      return;

    UpdateEmptyFieldSubobjects(RD, RD, ElementOffset,
                               PlacingOverlappingField);
    ElementOffset += Layout.getSize();
  }
}
573}

575typedef llvm::SmallPtrSet<const CXXRecordDecl*, 4> ClassSetTy;

577class ItaniumRecordLayoutBuilder {
578protected:
// FIXME: Remove this and make the appropriate fields public.
friend class clang::ASTContext;

const ASTContext &Context;

EmptySubobjectMap *EmptySubobjects;

/// Size - The current size of the record layout.
uint64_t Size;

/// Alignment - The current alignment of the record layout.
CharUnits Alignment;

/// PreferredAlignment - The preferred alignment of the record layout.
CharUnits PreferredAlignment;

/// The alignment if attribute packed is not used.
CharUnits UnpackedAlignment;

/// \brief The maximum of the alignments of top-level members.
CharUnits UnadjustedAlignment;

SmallVector<uint64_t, 16> FieldOffsets;

/// Whether the external AST source has provided a layout for this
/// record.
unsigned UseExternalLayout : 1;

/// Whether we need to infer alignment, even when we have an
/// externally-provided layout.
unsigned InferAlignment : 1;

/// Packed - Whether the record is packed or not.
unsigned Packed : 1;

unsigned IsUnion : 1;

unsigned IsMac68kAlign : 1;

unsigned IsNaturalAlign : 1;

unsigned IsMsStruct : 1;

/// UnfilledBitsInLastUnit - If the last field laid out was a bitfield,
/// this contains the number of bits in the last unit that can be used for
/// an adjacent bitfield if necessary.  The unit in question is usually
/// a byte, but larger units are used if IsMsStruct.
unsigned char UnfilledBitsInLastUnit;

/// LastBitfieldStorageUnitSize - If IsMsStruct, represents the size of the
/// storage unit of the previous field if it was a bitfield.
unsigned char LastBitfieldStorageUnitSize;

/// MaxFieldAlignment - The maximum allowed field alignment. This is set by
/// #pragma pack.
CharUnits MaxFieldAlignment;

/// DataSize - The data size of the record being laid out.
uint64_t DataSize;

CharUnits NonVirtualSize;
CharUnits NonVirtualAlignment;
CharUnits PreferredNVAlignment;

/// If we've laid out a field but not included its tail padding in Size yet,
/// this is the size up to the end of that field.
CharUnits PaddedFieldSize;

/// PrimaryBase - the primary base class (if one exists) of the class
/// we're laying out.
const CXXRecordDecl *PrimaryBase;

/// PrimaryBaseIsVirtual - Whether the primary base of the class we're laying
/// out is virtual.
bool PrimaryBaseIsVirtual;

/// HasOwnVFPtr - Whether the class provides its own vtable/vftbl
/// pointer, as opposed to inheriting one from a primary base class.
bool HasOwnVFPtr;

/// the flag of field offset changing due to packed attribute.
bool HasPackedField;

/// HandledFirstNonOverlappingEmptyField - An auxiliary field used for AIX.
/// When there are OverlappingEmptyFields existing in the aggregate, the
/// flag shows if the following first non-empty or empty-but-non-overlapping
/// field has been handled, if any.
bool HandledFirstNonOverlappingEmptyField;

typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsetsMapTy;

/// Bases - base classes and their offsets in the record.
BaseOffsetsMapTy Bases;

// VBases - virtual base classes and their offsets in the record.
ASTRecordLayout::VBaseOffsetsMapTy VBases;

/// IndirectPrimaryBases - Virtual base classes, direct or indirect, that are
/// primary base classes for some other direct or indirect base class.
CXXIndirectPrimaryBaseSet IndirectPrimaryBases;

/// FirstNearlyEmptyVBase - The first nearly empty virtual base class in
/// inheritance graph order. Used for determining the primary base class.
const CXXRecordDecl *FirstNearlyEmptyVBase;

/// VisitedVirtualBases - A set of all the visited virtual bases, used to
/// avoid visiting virtual bases more than once.
llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBases;

/// Valid if UseExternalLayout is true.
ExternalLayout External;

ItaniumRecordLayoutBuilder(const ASTContext &Context,
                           EmptySubobjectMap *EmptySubobjects)
    : Context(Context), EmptySubobjects(EmptySubobjects), Size(0),
      Alignment(CharUnits::One()), PreferredAlignment(CharUnits::One()),
      UnpackedAlignment(CharUnits::One()),
      UnadjustedAlignment(CharUnits::One()), UseExternalLayout(false),
      InferAlignment(false), Packed(false), IsUnion(false),
      IsMac68kAlign(false),
      IsNaturalAlign(!Context.getTargetInfo().getTriple().isOSAIX()),
      IsMsStruct(false), UnfilledBitsInLastUnit(0),
      LastBitfieldStorageUnitSize(0), MaxFieldAlignment(CharUnits::Zero()),
      DataSize(0), NonVirtualSize(CharUnits::Zero()),
      NonVirtualAlignment(CharUnits::One()),
      PreferredNVAlignment(CharUnits::One()),
      PaddedFieldSize(CharUnits::Zero()), PrimaryBase(nullptr),
      PrimaryBaseIsVirtual(false), HasOwnVFPtr(false), HasPackedField(false),
      HandledFirstNonOverlappingEmptyField(false),
      FirstNearlyEmptyVBase(nullptr) {}

void Layout(const RecordDecl *D);
void Layout(const CXXRecordDecl *D);
void Layout(const ObjCInterfaceDecl *D);

void LayoutFields(const RecordDecl *D);
void LayoutField(const FieldDecl *D, bool InsertExtraPadding);
void LayoutWideBitField(uint64_t FieldSize, uint64_t StorageUnitSize,
                        bool FieldPacked, const FieldDecl *D);
void LayoutBitField(const FieldDecl *D);

TargetCXXABI getCXXABI() const {
  return Context.getTargetInfo().getCXXABI();
}

/// BaseSubobjectInfoAllocator - Allocator for BaseSubobjectInfo objects.
llvm::SpecificBumpPtrAllocator<BaseSubobjectInfo> BaseSubobjectInfoAllocator;

typedef llvm::DenseMap<const CXXRecordDecl *, BaseSubobjectInfo *>
  BaseSubobjectInfoMapTy;

/// VirtualBaseInfo - Map from all the (direct or indirect) virtual bases
/// of the class we're laying out to their base subobject info.
BaseSubobjectInfoMapTy VirtualBaseInfo;

/// NonVirtualBaseInfo - Map from all the direct non-virtual bases of the
/// class we're laying out to their base subobject info.
BaseSubobjectInfoMapTy NonVirtualBaseInfo;

/// ComputeBaseSubobjectInfo - Compute the base subobject information for the
/// bases of the given class.
void ComputeBaseSubobjectInfo(const CXXRecordDecl *RD);

/// ComputeBaseSubobjectInfo - Compute the base subobject information for a
/// single class and all of its base classes.
BaseSubobjectInfo *ComputeBaseSubobjectInfo(const CXXRecordDecl *RD,
                                            bool IsVirtual,
                                            BaseSubobjectInfo *Derived);

/// DeterminePrimaryBase - Determine the primary base of the given class.
void DeterminePrimaryBase(const CXXRecordDecl *RD);

void SelectPrimaryVBase(const CXXRecordDecl *RD);

void EnsureVTablePointerAlignment(CharUnits UnpackedBaseAlign);

/// LayoutNonVirtualBases - Determines the primary base class (if any) and
/// lays it out. Will then proceed to lay out all non-virtual base clasess.
void LayoutNonVirtualBases(const CXXRecordDecl *RD);

/// LayoutNonVirtualBase - Lays out a single non-virtual base.
void LayoutNonVirtualBase(const BaseSubobjectInfo *Base);

void AddPrimaryVirtualBaseOffsets(const BaseSubobjectInfo *Info,
                                  CharUnits Offset);

/// LayoutVirtualBases - Lays out all the virtual bases.
void LayoutVirtualBases(const CXXRecordDecl *RD,
                        const CXXRecordDecl *MostDerivedClass);

/// LayoutVirtualBase - Lays out a single virtual base.
void LayoutVirtualBase(const BaseSubobjectInfo *Base);

/// LayoutBase - Will lay out a base and return the offset where it was
/// placed, in chars.
CharUnits LayoutBase(const BaseSubobjectInfo *Base);

/// InitializeLayout - Initialize record layout for the given record decl.
void InitializeLayout(const Decl *D);

/// FinishLayout - Finalize record layout. Adjust record size based on the
/// alignment.
void FinishLayout(const NamedDecl *D);

void UpdateAlignment(CharUnits NewAlignment, CharUnits UnpackedNewAlignment,
                     CharUnits PreferredAlignment);
void UpdateAlignment(CharUnits NewAlignment, CharUnits UnpackedNewAlignment) {
  UpdateAlignment(NewAlignment, UnpackedNewAlignment, NewAlignment);
}
void UpdateAlignment(CharUnits NewAlignment) {
  UpdateAlignment(NewAlignment, NewAlignment, NewAlignment);
}

/// Retrieve the externally-supplied field offset for the given
/// field.
///
/// \param Field The field whose offset is being queried.
/// \param ComputedOffset The offset that we've computed for this field.
uint64_t updateExternalFieldOffset(const FieldDecl *Field,
                                   uint64_t ComputedOffset);

void CheckFieldPadding(uint64_t Offset, uint64_t UnpaddedOffset,
                        uint64_t UnpackedOffset, unsigned UnpackedAlign,
                        bool isPacked, const FieldDecl *D);

DiagnosticBuilder Diag(SourceLocation Loc, unsigned DiagID);

CharUnits getSize() const {
  assert(Size % Context.getCharWidth() == 0)((void)0);
  return Context.toCharUnitsFromBits(Size);
}
uint64_t getSizeInBits() const { return Size; }

void setSize(CharUnits NewSize) { Size = Context.toBits(NewSize); }
void setSize(uint64_t NewSize) { Size = NewSize; }

CharUnits getAligment() const { return Alignment; }

CharUnits getDataSize() const {
  assert(DataSize % Context.getCharWidth() == 0)((void)0);
  return Context.toCharUnitsFromBits(DataSize);
}
uint64_t getDataSizeInBits() const { return DataSize; }

void setDataSize(CharUnits NewSize) { DataSize = Context.toBits(NewSize); }
void setDataSize(uint64_t NewSize) { DataSize = NewSize; }

ItaniumRecordLayoutBuilder(const ItaniumRecordLayoutBuilder &) = delete;
void operator=(const ItaniumRecordLayoutBuilder &) = delete;
828};
829} // end anonymous namespace

831void ItaniumRecordLayoutBuilder::SelectPrimaryVBase(const CXXRecordDecl *RD) {
for (const auto &I : RD->bases()) {
  assert(!I.getType()->isDependentType() &&((void)0)
         "Cannot layout class with dependent bases.")((void)0);

  const CXXRecordDecl *Base = I.getType()->getAsCXXRecordDecl();

  // Check if this is a nearly empty virtual base.
  if (I.isVirtual() && Context.isNearlyEmpty(Base)) {
    // If it's not an indirect primary base, then we've found our primary
    // base.
    if (!IndirectPrimaryBases.count(Base)) {
      PrimaryBase = Base;
      PrimaryBaseIsVirtual = true;
      return;
    }

    // Is this the first nearly empty virtual base?
    if (!FirstNearlyEmptyVBase)
      FirstNearlyEmptyVBase = Base;
  }

  SelectPrimaryVBase(Base);
  if (PrimaryBase)
    return;
}
857}

859/// DeterminePrimaryBase - Determine the primary base of the given class.
860void ItaniumRecordLayoutBuilder::DeterminePrimaryBase(const CXXRecordDecl *RD) {
// If the class isn't dynamic, it won't have a primary base.
if (!RD->isDynamicClass())
  return;

// Compute all the primary virtual bases for all of our direct and
// indirect bases, and record all their primary virtual base classes.
RD->getIndirectPrimaryBases(IndirectPrimaryBases);

// If the record has a dynamic base class, attempt to choose a primary base
// class. It is the first (in direct base class order) non-virtual dynamic
// base class, if one exists.
for (const auto &I : RD->bases()) {
  // Ignore virtual bases.
  if (I.isVirtual())
    continue;

  const CXXRecordDecl *Base = I.getType()->getAsCXXRecordDecl();

  if (Base->isDynamicClass()) {
    // We found it.
    PrimaryBase = Base;
    PrimaryBaseIsVirtual = false;
    return;
  }
}

// Under the Itanium ABI, if there is no non-virtual primary base class,
// try to compute the primary virtual base.  The primary virtual base is
// the first nearly empty virtual base that is not an indirect primary
// virtual base class, if one exists.
if (RD->getNumVBases() != 0) {
  SelectPrimaryVBase(RD);
  if (PrimaryBase)
    return;
}

// Otherwise, it is the first indirect primary base class, if one exists.
if (FirstNearlyEmptyVBase) {
  PrimaryBase = FirstNearlyEmptyVBase;
  PrimaryBaseIsVirtual = true;
  return;
}

assert(!PrimaryBase && "Should not get here with a primary base!")((void)0);
905}

907BaseSubobjectInfo *ItaniumRecordLayoutBuilder::ComputeBaseSubobjectInfo(
  const CXXRecordDecl *RD, bool IsVirtual, BaseSubobjectInfo *Derived) {
BaseSubobjectInfo *Info;

if (IsVirtual) {
  // Check if we already have info about this virtual base.
  BaseSubobjectInfo *&InfoSlot = VirtualBaseInfo[RD];
  if (InfoSlot) {
    assert(InfoSlot->Class == RD && "Wrong class for virtual base info!")((void)0);
    return InfoSlot;
  }

  // We don't, create it.
  InfoSlot = new (BaseSubobjectInfoAllocator.Allocate()) BaseSubobjectInfo;
  Info = InfoSlot;
} else {
  Info = new (BaseSubobjectInfoAllocator.Allocate()) BaseSubobjectInfo;
}

Info->Class = RD;
Info->IsVirtual = IsVirtual;
Info->Derived = nullptr;
Info->PrimaryVirtualBaseInfo = nullptr;

const CXXRecordDecl *PrimaryVirtualBase = nullptr;
BaseSubobjectInfo *PrimaryVirtualBaseInfo = nullptr;

// Check if this base has a primary virtual base.
if (RD->getNumVBases()) {
  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
  if (Layout.isPrimaryBaseVirtual()) {
    // This base does have a primary virtual base.
    PrimaryVirtualBase = Layout.getPrimaryBase();
    assert(PrimaryVirtualBase && "Didn't have a primary virtual base!")((void)0);

    // Now check if we have base subobject info about this primary base.
    PrimaryVirtualBaseInfo = VirtualBaseInfo.lookup(PrimaryVirtualBase);

    if (PrimaryVirtualBaseInfo) {
      if (PrimaryVirtualBaseInfo->Derived) {
        // We did have info about this primary base, and it turns out that it
        // has already been claimed as a primary virtual base for another
        // base.
        PrimaryVirtualBase = nullptr;
      } else {
        // We can claim this base as our primary base.
        Info->PrimaryVirtualBaseInfo = PrimaryVirtualBaseInfo;
        PrimaryVirtualBaseInfo->Derived = Info;
      }
    }
  }
}

// Now go through all direct bases.
for (const auto &I : RD->bases()) {
  bool IsVirtual = I.isVirtual();

  const CXXRecordDecl *BaseDecl = I.getType()->getAsCXXRecordDecl();

  Info->Bases.push_back(ComputeBaseSubobjectInfo(BaseDecl, IsVirtual, Info));
}

if (PrimaryVirtualBase && !PrimaryVirtualBaseInfo) {
  // Traversing the bases must have created the base info for our primary
  // virtual base.
  PrimaryVirtualBaseInfo = VirtualBaseInfo.lookup(PrimaryVirtualBase);
  assert(PrimaryVirtualBaseInfo &&((void)0)
         "Did not create a primary virtual base!")((void)0);

  // Claim the primary virtual base as our primary virtual base.
  Info->PrimaryVirtualBaseInfo = PrimaryVirtualBaseInfo;
  PrimaryVirtualBaseInfo->Derived = Info;
}

return Info;
982}

984void ItaniumRecordLayoutBuilder::ComputeBaseSubobjectInfo(
  const CXXRecordDecl *RD) {
for (const auto &I : RD->bases()) {
  bool IsVirtual = I.isVirtual();

  const CXXRecordDecl *BaseDecl = I.getType()->getAsCXXRecordDecl();

  // Compute the base subobject info for this base.
  BaseSubobjectInfo *Info = ComputeBaseSubobjectInfo(BaseDecl, IsVirtual,
                                                     nullptr);

  if (IsVirtual) {
    // ComputeBaseInfo has already added this base for us.
    assert(VirtualBaseInfo.count(BaseDecl) &&((void)0)
           "Did not add virtual base!")((void)0);
  } else {
    // Add the base info to the map of non-virtual bases.
    assert(!NonVirtualBaseInfo.count(BaseDecl) &&((void)0)
           "Non-virtual base already exists!")((void)0);
    NonVirtualBaseInfo.insert(std::make_pair(BaseDecl, Info));
  }
}
1006}

1008void ItaniumRecordLayoutBuilder::EnsureVTablePointerAlignment(
  CharUnits UnpackedBaseAlign) {
CharUnits BaseAlign = Packed ? CharUnits::One() : UnpackedBaseAlign;

// The maximum field alignment overrides base align.
if (!MaxFieldAlignment.isZero()) {
  BaseAlign = std::min(BaseAlign, MaxFieldAlignment);
  UnpackedBaseAlign = std::min(UnpackedBaseAlign, MaxFieldAlignment);
}

// Round up the current record size to pointer alignment.
setSize(getSize().alignTo(BaseAlign));

// Update the alignment.
UpdateAlignment(BaseAlign, UnpackedBaseAlign, BaseAlign);
1023}

1025void ItaniumRecordLayoutBuilder::LayoutNonVirtualBases(
  const CXXRecordDecl *RD) {
// Then, determine the primary base class.
DeterminePrimaryBase(RD);

// Compute base subobject info.
ComputeBaseSubobjectInfo(RD);

// If we have a primary base class, lay it out.
if (PrimaryBase) {
  if (PrimaryBaseIsVirtual) {
    // If the primary virtual base was a primary virtual base of some other
    // base class we'll have to steal it.
    BaseSubobjectInfo *PrimaryBaseInfo = VirtualBaseInfo.lookup(PrimaryBase);
    PrimaryBaseInfo->Derived = nullptr;

    // We have a virtual primary base, insert it as an indirect primary base.
    IndirectPrimaryBases.insert(PrimaryBase);

    assert(!VisitedVirtualBases.count(PrimaryBase) &&((void)0)
           "vbase already visited!")((void)0);
    VisitedVirtualBases.insert(PrimaryBase);

    LayoutVirtualBase(PrimaryBaseInfo);
  } else {
    BaseSubobjectInfo *PrimaryBaseInfo =
      NonVirtualBaseInfo.lookup(PrimaryBase);
    assert(PrimaryBaseInfo &&((void)0)
           "Did not find base info for non-virtual primary base!")((void)0);

    LayoutNonVirtualBase(PrimaryBaseInfo);
  }

// If this class needs a vtable/vf-table and didn't get one from a
// primary base, add it in now.
} else if (RD->isDynamicClass()) {
  assert(DataSize == 0 && "Vtable pointer must be at offset zero!")((void)0);
  CharUnits PtrWidth =
    Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
  CharUnits PtrAlign =
    Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerAlign(0));
  EnsureVTablePointerAlignment(PtrAlign);
  HasOwnVFPtr = true;

  assert(!IsUnion && "Unions cannot be dynamic classes.")((void)0);
  HandledFirstNonOverlappingEmptyField = true;

  setSize(getSize() + PtrWidth);
  setDataSize(getSize());
}

// Now lay out the non-virtual bases.
for (const auto &I : RD->bases()) {

  // Ignore virtual bases.
  if (I.isVirtual())
    continue;

  const CXXRecordDecl *BaseDecl = I.getType()->getAsCXXRecordDecl();

  // Skip the primary base, because we've already laid it out.  The
  // !PrimaryBaseIsVirtual check is required because we might have a
  // non-virtual base of the same type as a primary virtual base.
  if (BaseDecl == PrimaryBase && !PrimaryBaseIsVirtual)
    continue;

  // Lay out the base.
  BaseSubobjectInfo *BaseInfo = NonVirtualBaseInfo.lookup(BaseDecl);
  assert(BaseInfo && "Did not find base info for non-virtual base!")((void)0);

  LayoutNonVirtualBase(BaseInfo);
}
1097}

1099void ItaniumRecordLayoutBuilder::LayoutNonVirtualBase(
  const BaseSubobjectInfo *Base) {
// Layout the base.
CharUnits Offset = LayoutBase(Base);

// Add its base class offset.
assert(!Bases.count(Base->Class) && "base offset already exists!")((void)0);
Bases.insert(std::make_pair(Base->Class, Offset));

AddPrimaryVirtualBaseOffsets(Base, Offset);
1109}

1111void ItaniumRecordLayoutBuilder::AddPrimaryVirtualBaseOffsets(
  const BaseSubobjectInfo *Info, CharUnits Offset) {
// This base isn't interesting, it has no virtual bases.
if (!Info->Class->getNumVBases())
  return;

// First, check if we have a virtual primary base to add offsets for.
if (Info->PrimaryVirtualBaseInfo) {
  assert(Info->PrimaryVirtualBaseInfo->IsVirtual &&((void)0)
         "Primary virtual base is not virtual!")((void)0);
  if (Info->PrimaryVirtualBaseInfo->Derived == Info) {
    // Add the offset.
    assert(!VBases.count(Info->PrimaryVirtualBaseInfo->Class) &&((void)0)
           "primary vbase offset already exists!")((void)0);
    VBases.insert(std::make_pair(Info->PrimaryVirtualBaseInfo->Class,
                                 ASTRecordLayout::VBaseInfo(Offset, false)));

    // Traverse the primary virtual base.
    AddPrimaryVirtualBaseOffsets(Info->PrimaryVirtualBaseInfo, Offset);
  }
}

// Now go through all direct non-virtual bases.
const ASTRecordLayout &Layout = Context.getASTRecordLayout(Info->Class);
for (const BaseSubobjectInfo *Base : Info->Bases) {
  if (Base->IsVirtual)
    continue;

  CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base->Class);
  AddPrimaryVirtualBaseOffsets(Base, BaseOffset);
}
1142}

1144void ItaniumRecordLayoutBuilder::LayoutVirtualBases(
  const CXXRecordDecl *RD, const CXXRecordDecl *MostDerivedClass) {
const CXXRecordDecl *PrimaryBase;
bool PrimaryBaseIsVirtual;

if (MostDerivedClass11.1
'MostDerivedClass' is equal to 'RD'
 == RD) {
12
←
Taking true branch→
  PrimaryBase = this->PrimaryBase;
  PrimaryBaseIsVirtual = this->PrimaryBaseIsVirtual;
} else {
  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
  PrimaryBase = Layout.getPrimaryBase();
  PrimaryBaseIsVirtual = Layout.isPrimaryBaseVirtual();
}

for (const CXXBaseSpecifier &Base : RD->bases()) {
13
←
Assuming '__begin1' is not equal to '__end1'→
  assert(!Base.getType()->isDependentType() &&((void)0)
         "Cannot layout class with dependent bases.")((void)0);

  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
14
←
'BaseDecl' initialized here→

  if (Base.isVirtual()) {
15
←
Assuming the condition is true→
16
←
Taking true branch→
    if (PrimaryBase != BaseDecl || !PrimaryBaseIsVirtual) {
17
←
Assuming 'PrimaryBase' is equal to 'BaseDecl'→
18
←
Assuming pointer value is null→
19
←
Assuming 'PrimaryBaseIsVirtual' is true→
20
←
Taking false branch→
      bool IndirectPrimaryBase = IndirectPrimaryBases.count(BaseDecl);

      // Only lay out the virtual base if it's not an indirect primary base.
      if (!IndirectPrimaryBase) {
        // Only visit virtual bases once.
        if (!VisitedVirtualBases.insert(BaseDecl).second)
          continue;

        const BaseSubobjectInfo *BaseInfo = VirtualBaseInfo.lookup(BaseDecl);
        assert(BaseInfo && "Did not find virtual base info!")((void)0);
        LayoutVirtualBase(BaseInfo);
      }
    }
  }

  if (!BaseDecl->getNumVBases()) {
21
←
Called C++ object pointer is null
    // This base isn't interesting since it doesn't have any virtual bases.
    continue;
  }

  LayoutVirtualBases(BaseDecl, MostDerivedClass);
}
1188}

1190void ItaniumRecordLayoutBuilder::LayoutVirtualBase(
  const BaseSubobjectInfo *Base) {
assert(!Base->Derived && "Trying to lay out a primary virtual base!")((void)0);

// Layout the base.
CharUnits Offset = LayoutBase(Base);

// Add its base class offset.
assert(!VBases.count(Base->Class) && "vbase offset already exists!")((void)0);
VBases.insert(std::make_pair(Base->Class,
                     ASTRecordLayout::VBaseInfo(Offset, false)));

AddPrimaryVirtualBaseOffsets(Base, Offset);
1203}

1205CharUnits
1206ItaniumRecordLayoutBuilder::LayoutBase(const BaseSubobjectInfo *Base) {
assert(!IsUnion && "Unions cannot have base classes.")((void)0);

const ASTRecordLayout &Layout = Context.getASTRecordLayout(Base->Class);
CharUnits Offset;

// Query the external layout to see if it provides an offset.
bool HasExternalLayout = false;
if (UseExternalLayout) {
  if (Base->IsVirtual)
    HasExternalLayout = External.getExternalVBaseOffset(Base->Class, Offset);
  else
    HasExternalLayout = External.getExternalNVBaseOffset(Base->Class, Offset);
}

auto getBaseOrPreferredBaseAlignFromUnpacked = [&](CharUnits UnpackedAlign) {
  // Clang <= 6 incorrectly applied the 'packed' attribute to base classes.
  // Per GCC's documentation, it only applies to non-static data members.
  return (Packed && ((Context.getLangOpts().getClangABICompat() <=
                      LangOptions::ClangABI::Ver6) ||
                     Context.getTargetInfo().getTriple().isPS4() ||
                     Context.getTargetInfo().getTriple().isOSAIX()))
             ? CharUnits::One()
             : UnpackedAlign;
};

CharUnits UnpackedBaseAlign = Layout.getNonVirtualAlignment();
CharUnits UnpackedPreferredBaseAlign = Layout.getPreferredNVAlignment();
CharUnits BaseAlign =
    getBaseOrPreferredBaseAlignFromUnpacked(UnpackedBaseAlign);
CharUnits PreferredBaseAlign =
    getBaseOrPreferredBaseAlignFromUnpacked(UnpackedPreferredBaseAlign);

const bool DefaultsToAIXPowerAlignment =
    Context.getTargetInfo().defaultsToAIXPowerAlignment();
if (DefaultsToAIXPowerAlignment) {
  // AIX `power` alignment does not apply the preferred alignment for
  // non-union classes if the source of the alignment (the current base in
  // this context) follows introduction of the first subobject with
  // exclusively allocated space or zero-extent array.
  if (!Base->Class->isEmpty() && !HandledFirstNonOverlappingEmptyField) {
    // By handling a base class that is not empty, we're handling the
    // "first (inherited) member".
    HandledFirstNonOverlappingEmptyField = true;
  } else if (!IsNaturalAlign) {
    UnpackedPreferredBaseAlign = UnpackedBaseAlign;
    PreferredBaseAlign = BaseAlign;
  }
}

CharUnits UnpackedAlignTo = !DefaultsToAIXPowerAlignment
                                ? UnpackedBaseAlign
                                : UnpackedPreferredBaseAlign;
// If we have an empty base class, try to place it at offset 0.
if (Base->Class->isEmpty() &&
    (!HasExternalLayout || Offset == CharUnits::Zero()) &&
    EmptySubobjects->CanPlaceBaseAtOffset(Base, CharUnits::Zero())) {
  setSize(std::max(getSize(), Layout.getSize()));
  UpdateAlignment(BaseAlign, UnpackedAlignTo, PreferredBaseAlign);

  return CharUnits::Zero();
}

// The maximum field alignment overrides the base align/(AIX-only) preferred
// base align.
if (!MaxFieldAlignment.isZero()) {
  BaseAlign = std::min(BaseAlign, MaxFieldAlignment);
  PreferredBaseAlign = std::min(PreferredBaseAlign, MaxFieldAlignment);
  UnpackedAlignTo = std::min(UnpackedAlignTo, MaxFieldAlignment);
}

CharUnits AlignTo =
    !DefaultsToAIXPowerAlignment ? BaseAlign : PreferredBaseAlign;
if (!HasExternalLayout) {
  // Round up the current record size to the base's alignment boundary.
  Offset = getDataSize().alignTo(AlignTo);

  // Try to place the base.
  while (!EmptySubobjects->CanPlaceBaseAtOffset(Base, Offset))
    Offset += AlignTo;
} else {
  bool Allowed = EmptySubobjects->CanPlaceBaseAtOffset(Base, Offset);
  (void)Allowed;
  assert(Allowed && "Base subobject externally placed at overlapping offset")((void)0);

  if (InferAlignment && Offset < getDataSize().alignTo(AlignTo)) {
    // The externally-supplied base offset is before the base offset we
    // computed. Assume that the structure is packed.
    Alignment = CharUnits::One();
    InferAlignment = false;
  }
}

if (!Base->Class->isEmpty()) {
  // Update the data size.
  setDataSize(Offset + Layout.getNonVirtualSize());

  setSize(std::max(getSize(), getDataSize()));
} else
  setSize(std::max(getSize(), Offset + Layout.getSize()));

// Remember max struct/class alignment.
UpdateAlignment(BaseAlign, UnpackedAlignTo, PreferredBaseAlign);

return Offset;
1311}

1313void ItaniumRecordLayoutBuilder::InitializeLayout(const Decl *D) {
if (const RecordDecl *RD = dyn_cast<RecordDecl>(D)) {
  IsUnion = RD->isUnion();
  IsMsStruct = RD->isMsStruct(Context);
}

Packed = D->hasAttr<PackedAttr>();

// Honor the default struct packing maximum alignment flag.
if (unsigned DefaultMaxFieldAlignment = Context.getLangOpts().PackStruct) {
  MaxFieldAlignment = CharUnits::fromQuantity(DefaultMaxFieldAlignment);
}

// mac68k alignment supersedes maximum field alignment and attribute aligned,
// and forces all structures to have 2-byte alignment. The IBM docs on it
// allude to additional (more complicated) semantics, especially with regard
// to bit-fields, but gcc appears not to follow that.
if (D->hasAttr<AlignMac68kAttr>()) {
  assert(((void)0)
      !D->hasAttr<AlignNaturalAttr>() &&((void)0)
      "Having both mac68k and natural alignment on a decl is not allowed.")((void)0);
  IsMac68kAlign = true;
  MaxFieldAlignment = CharUnits::fromQuantity(2);
  Alignment = CharUnits::fromQuantity(2);
  PreferredAlignment = CharUnits::fromQuantity(2);
} else {
  if (D->hasAttr<AlignNaturalAttr>())
    IsNaturalAlign = true;

  if (const MaxFieldAlignmentAttr *MFAA = D->getAttr<MaxFieldAlignmentAttr>())
    MaxFieldAlignment = Context.toCharUnitsFromBits(MFAA->getAlignment());

  if (unsigned MaxAlign = D->getMaxAlignment())
    UpdateAlignment(Context.toCharUnitsFromBits(MaxAlign));
}

HandledFirstNonOverlappingEmptyField =
    !Context.getTargetInfo().defaultsToAIXPowerAlignment() || IsNaturalAlign;

// If there is an external AST source, ask it for the various offsets.
if (const RecordDecl *RD = dyn_cast<RecordDecl>(D))
  if (ExternalASTSource *Source = Context.getExternalSource()) {
    UseExternalLayout = Source->layoutRecordType(
        RD, External.Size, External.Align, External.FieldOffsets,
        External.BaseOffsets, External.VirtualBaseOffsets);

    // Update based on external alignment.
    if (UseExternalLayout) {
      if (External.Align > 0) {
        Alignment = Context.toCharUnitsFromBits(External.Align);
        PreferredAlignment = Context.toCharUnitsFromBits(External.Align);
      } else {
        // The external source didn't have alignment information; infer it.
        InferAlignment = true;
      }
    }
  }
1370}

1372void ItaniumRecordLayoutBuilder::Layout(const RecordDecl *D) {
InitializeLayout(D);
LayoutFields(D);

// Finally, round the size of the total struct up to the alignment of the
// struct itself.
FinishLayout(D);
1379}

1381void ItaniumRecordLayoutBuilder::Layout(const CXXRecordDecl *RD) {
InitializeLayout(RD);

// Lay out the vtable and the non-virtual bases.
LayoutNonVirtualBases(RD);

LayoutFields(RD);

NonVirtualSize = Context.toCharUnitsFromBits(
    llvm::alignTo(getSizeInBits(), Context.getTargetInfo().getCharAlign()));
NonVirtualAlignment = Alignment;
PreferredNVAlignment = PreferredAlignment;

// Lay out the virtual bases and add the primary virtual base offsets.
LayoutVirtualBases(RD, RD);
11
←
Calling 'ItaniumRecordLayoutBuilder::LayoutVirtualBases'→

// Finally, round the size of the total struct up to the alignment
// of the struct itself.
FinishLayout(RD);

1401#ifndef NDEBUG1
// Check that we have base offsets for all bases.
for (const CXXBaseSpecifier &Base : RD->bases()) {
  if (Base.isVirtual())
    continue;

  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();

  assert(Bases.count(BaseDecl) && "Did not find base offset!")((void)0);
}

// And all virtual bases.
for (const CXXBaseSpecifier &Base : RD->vbases()) {
  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();

  assert(VBases.count(BaseDecl) && "Did not find base offset!")((void)0);
}
1418#endif
1419}

1421void ItaniumRecordLayoutBuilder::Layout(const ObjCInterfaceDecl *D) {
if (ObjCInterfaceDecl *SD = D->getSuperClass()) {
  const ASTRecordLayout &SL = Context.getASTObjCInterfaceLayout(SD);

  UpdateAlignment(SL.getAlignment());

  // We start laying out ivars not at the end of the superclass
  // structure, but at the next byte following the last field.
  setDataSize(SL.getDataSize());
  setSize(getDataSize());
}

InitializeLayout(D);
// Layout each ivar sequentially.
for (const ObjCIvarDecl *IVD = D->all_declared_ivar_begin(); IVD;
     IVD = IVD->getNextIvar())
  LayoutField(IVD, false);

// Finally, round the size of the total struct up to the alignment of the
// struct itself.
FinishLayout(D);
1442}

1444void ItaniumRecordLayoutBuilder::LayoutFields(const RecordDecl *D) {
// Layout each field, for now, just sequentially, respecting alignment.  In
// the future, this will need to be tweakable by targets.
bool InsertExtraPadding = D->mayInsertExtraPadding(/*EmitRemark=*/true);
bool HasFlexibleArrayMember = D->hasFlexibleArrayMember();
for (auto I = D->field_begin(), End = D->field_end(); I != End; ++I) {
  auto Next(I);
  ++Next;
  LayoutField(*I,
              InsertExtraPadding && (Next != End || !HasFlexibleArrayMember));
}
1455}

1457// Rounds the specified size to have it a multiple of the char size.
1458static uint64_t
1459roundUpSizeToCharAlignment(uint64_t Size,
                         const ASTContext &Context) {
uint64_t CharAlignment = Context.getTargetInfo().getCharAlign();
return llvm::alignTo(Size, CharAlignment);
1463}

1465void ItaniumRecordLayoutBuilder::LayoutWideBitField(uint64_t FieldSize,
                                                  uint64_t StorageUnitSize,
                                                  bool FieldPacked,
                                                  const FieldDecl *D) {
assert(Context.getLangOpts().CPlusPlus &&((void)0)
       "Can only have wide bit-fields in C++!")((void)0);

// Itanium C++ ABI 2.4:
//   If sizeof(T)*8 < n, let T' be the largest integral POD type with
//   sizeof(T')*8 <= n.

QualType IntegralPODTypes[] = {
  Context.UnsignedCharTy, Context.UnsignedShortTy, Context.UnsignedIntTy,
  Context.UnsignedLongTy, Context.UnsignedLongLongTy
};

QualType Type;
for (const QualType &QT : IntegralPODTypes) {
  uint64_t Size = Context.getTypeSize(QT);

  if (Size > FieldSize)
    break;

  Type = QT;
}
assert(!Type.isNull() && "Did not find a type!")((void)0);

CharUnits TypeAlign = Context.getTypeAlignInChars(Type);

// We're not going to use any of the unfilled bits in the last byte.
UnfilledBitsInLastUnit = 0;
LastBitfieldStorageUnitSize = 0;

uint64_t FieldOffset;
uint64_t UnpaddedFieldOffset = getDataSizeInBits() - UnfilledBitsInLastUnit;

if (IsUnion) {
  uint64_t RoundedFieldSize = roundUpSizeToCharAlignment(FieldSize,
                                                         Context);
  setDataSize(std::max(getDataSizeInBits(), RoundedFieldSize));
  FieldOffset = 0;
} else {
  // The bitfield is allocated starting at the next offset aligned
  // appropriately for T', with length n bits.
  FieldOffset = llvm::alignTo(getDataSizeInBits(), Context.toBits(TypeAlign));

  uint64_t NewSizeInBits = FieldOffset + FieldSize;

  setDataSize(
      llvm::alignTo(NewSizeInBits, Context.getTargetInfo().getCharAlign()));
  UnfilledBitsInLastUnit = getDataSizeInBits() - NewSizeInBits;
}

// Place this field at the current location.
FieldOffsets.push_back(FieldOffset);

CheckFieldPadding(FieldOffset, UnpaddedFieldOffset, FieldOffset,
                  Context.toBits(TypeAlign), FieldPacked, D);

// Update the size.
setSize(std::max(getSizeInBits(), getDataSizeInBits()));

// Remember max struct/class alignment.
UpdateAlignment(TypeAlign);
1529}

1531static bool isAIXLayout(const ASTContext &Context) {
return Context.getTargetInfo().getTriple().getOS() == llvm::Triple::AIX;
1533}

1535void ItaniumRecordLayoutBuilder::LayoutBitField(const FieldDecl *D) {
bool FieldPacked = Packed || D->hasAttr<PackedAttr>();
uint64_t FieldSize = D->getBitWidthValue(Context);
TypeInfo FieldInfo = Context.getTypeInfo(D->getType());
uint64_t StorageUnitSize = FieldInfo.Width;
unsigned FieldAlign = FieldInfo.Align;
bool AlignIsRequired = FieldInfo.AlignIsRequired;

// UnfilledBitsInLastUnit is the difference between the end of the
// last allocated bitfield (i.e. the first bit offset available for
// bitfields) and the end of the current data size in bits (i.e. the
// first bit offset available for non-bitfields).  The current data
// size in bits is always a multiple of the char size; additionally,
// for ms_struct records it's also a multiple of the
// LastBitfieldStorageUnitSize (if set).

// The struct-layout algorithm is dictated by the platform ABI,
// which in principle could use almost any rules it likes.  In
// practice, UNIXy targets tend to inherit the algorithm described
// in the System V generic ABI.  The basic bitfield layout rule in
// System V is to place bitfields at the next available bit offset
// where the entire bitfield would fit in an aligned storage unit of
// the declared type; it's okay if an earlier or later non-bitfield
// is allocated in the same storage unit.  However, some targets
// (those that !useBitFieldTypeAlignment(), e.g. ARM APCS) don't
// require this storage unit to be aligned, and therefore always put
// the bitfield at the next available bit offset.

// ms_struct basically requests a complete replacement of the
// platform ABI's struct-layout algorithm, with the high-level goal
// of duplicating MSVC's layout.  For non-bitfields, this follows
// the standard algorithm.  The basic bitfield layout rule is to
// allocate an entire unit of the bitfield's declared type
// (e.g. 'unsigned long'), then parcel it up among successive
// bitfields whose declared types have the same size, making a new
// unit as soon as the last can no longer store the whole value.
// Since it completely replaces the platform ABI's algorithm,
// settings like !useBitFieldTypeAlignment() do not apply.

// A zero-width bitfield forces the use of a new storage unit for
// later bitfields.  In general, this occurs by rounding up the
// current size of the struct as if the algorithm were about to
// place a non-bitfield of the field's formal type.  Usually this
// does not change the alignment of the struct itself, but it does
// on some targets (those that useZeroLengthBitfieldAlignment(),
// e.g. ARM).  In ms_struct layout, zero-width bitfields are
// ignored unless they follow a non-zero-width bitfield.

// A field alignment restriction (e.g. from #pragma pack) or
// specification (e.g. from __attribute__((aligned))) changes the
// formal alignment of the field.  For System V, this alters the
// required alignment of the notional storage unit that must contain
// the bitfield.  For ms_struct, this only affects the placement of
// new storage units.  In both cases, the effect of #pragma pack is
// ignored on zero-width bitfields.

// On System V, a packed field (e.g. from #pragma pack or
// __attribute__((packed))) always uses the next available bit
// offset.

// In an ms_struct struct, the alignment of a fundamental type is
// always equal to its size.  This is necessary in order to mimic
// the i386 alignment rules on targets which might not fully align
// all types (e.g. Darwin PPC32, where alignof(long long) == 4).

// First, some simple bookkeeping to perform for ms_struct structs.
if (IsMsStruct) {
  // The field alignment for integer types is always the size.
  FieldAlign = StorageUnitSize;

  // If the previous field was not a bitfield, or was a bitfield
  // with a different storage unit size, or if this field doesn't fit into
  // the current storage unit, we're done with that storage unit.
  if (LastBitfieldStorageUnitSize != StorageUnitSize ||
      UnfilledBitsInLastUnit < FieldSize) {
    // Also, ignore zero-length bitfields after non-bitfields.
    if (!LastBitfieldStorageUnitSize && !FieldSize)
      FieldAlign = 1;

    UnfilledBitsInLastUnit = 0;
    LastBitfieldStorageUnitSize = 0;
  }
}

if (isAIXLayout(Context)) {
  if (StorageUnitSize < Context.getTypeSize(Context.UnsignedIntTy)) {
    // On AIX, [bool, char, short] bitfields have the same alignment
    // as [unsigned].
    StorageUnitSize = Context.getTypeSize(Context.UnsignedIntTy);
  } else if (StorageUnitSize > Context.getTypeSize(Context.UnsignedIntTy) &&
             Context.getTargetInfo().getTriple().isArch32Bit() &&
             FieldSize <= 32) {
    // Under 32-bit compile mode, the bitcontainer is 32 bits if a single
    // long long bitfield has length no greater than 32 bits.
    StorageUnitSize = 32;

    if (!AlignIsRequired)
      FieldAlign = 32;
  }

  if (FieldAlign < StorageUnitSize) {
    // The bitfield alignment should always be greater than or equal to
    // bitcontainer size.
    FieldAlign = StorageUnitSize;
  }
}

// If the field is wider than its declared type, it follows
// different rules in all cases, except on AIX.
// On AIX, wide bitfield follows the same rules as normal bitfield.
if (FieldSize > StorageUnitSize && !isAIXLayout(Context)) {
  LayoutWideBitField(FieldSize, StorageUnitSize, FieldPacked, D);
  return;
}

// Compute the next available bit offset.
uint64_t FieldOffset =
  IsUnion ? 0 : (getDataSizeInBits() - UnfilledBitsInLastUnit);

// Handle targets that don't honor bitfield type alignment.
if (!IsMsStruct && !Context.getTargetInfo().useBitFieldTypeAlignment()) {
  // Some such targets do honor it on zero-width bitfields.
  if (FieldSize == 0 &&
      Context.getTargetInfo().useZeroLengthBitfieldAlignment()) {
    // Some targets don't honor leading zero-width bitfield.
    if (!IsUnion && FieldOffset == 0 &&
        !Context.getTargetInfo().useLeadingZeroLengthBitfield())
      FieldAlign = 1;
    else {
      // The alignment to round up to is the max of the field's natural
      // alignment and a target-specific fixed value (sometimes zero).
      unsigned ZeroLengthBitfieldBoundary =
          Context.getTargetInfo().getZeroLengthBitfieldBoundary();
      FieldAlign = std::max(FieldAlign, ZeroLengthBitfieldBoundary);
    }
  // If that doesn't apply, just ignore the field alignment.
  } else {
    FieldAlign = 1;
  }
}

// Remember the alignment we would have used if the field were not packed.
unsigned UnpackedFieldAlign = FieldAlign;

// Ignore the field alignment if the field is packed unless it has zero-size.
if (!IsMsStruct && FieldPacked && FieldSize != 0)
  FieldAlign = 1;

// But, if there's an 'aligned' attribute on the field, honor that.
unsigned ExplicitFieldAlign = D->getMaxAlignment();
if (ExplicitFieldAlign) {
  FieldAlign = std::max(FieldAlign, ExplicitFieldAlign);
  UnpackedFieldAlign = std::max(UnpackedFieldAlign, ExplicitFieldAlign);
}

// But, if there's a #pragma pack in play, that takes precedent over
// even the 'aligned' attribute, for non-zero-width bitfields.
unsigned MaxFieldAlignmentInBits = Context.toBits(MaxFieldAlignment);
if (!MaxFieldAlignment.isZero() && FieldSize) {
  UnpackedFieldAlign = std::min(UnpackedFieldAlign, MaxFieldAlignmentInBits);
  if (FieldPacked)
    FieldAlign = UnpackedFieldAlign;
  else
    FieldAlign = std::min(FieldAlign, MaxFieldAlignmentInBits);
}

// But, ms_struct just ignores all of that in unions, even explicit
// alignment attributes.
if (IsMsStruct && IsUnion) {
  FieldAlign = UnpackedFieldAlign = 1;
}

// For purposes of diagnostics, we're going to simultaneously
// compute the field offsets that we would have used if we weren't
// adding any alignment padding or if the field weren't packed.
uint64_t UnpaddedFieldOffset = FieldOffset;
uint64_t UnpackedFieldOffset = FieldOffset;

// Check if we need to add padding to fit the bitfield within an
// allocation unit with the right size and alignment.  The rules are
// somewhat different here for ms_struct structs.
if (IsMsStruct) {
  // If it's not a zero-width bitfield, and we can fit the bitfield
  // into the active storage unit (and we haven't already decided to
  // start a new storage unit), just do so, regardless of any other
  // other consideration.  Otherwise, round up to the right alignment.
  if (FieldSize == 0 || FieldSize > UnfilledBitsInLastUnit) {
    FieldOffset = llvm::alignTo(FieldOffset, FieldAlign);
    UnpackedFieldOffset =
        llvm::alignTo(UnpackedFieldOffset, UnpackedFieldAlign);
    UnfilledBitsInLastUnit = 0;
  }

} else {
  // #pragma pack, with any value, suppresses the insertion of padding.
  bool AllowPadding = MaxFieldAlignment.isZero();

  // Compute the real offset.
  if (FieldSize == 0 ||
      (AllowPadding &&
       (FieldOffset & (FieldAlign - 1)) + FieldSize > StorageUnitSize)) {
    FieldOffset = llvm::alignTo(FieldOffset, FieldAlign);
  } else if (ExplicitFieldAlign &&
             (MaxFieldAlignmentInBits == 0 ||
              ExplicitFieldAlign <= MaxFieldAlignmentInBits) &&
             Context.getTargetInfo().useExplicitBitFieldAlignment()) {
    // TODO: figure it out what needs to be done on targets that don't honor
    // bit-field type alignment like ARM APCS ABI.
    FieldOffset = llvm::alignTo(FieldOffset, ExplicitFieldAlign);
  }

  // Repeat the computation for diagnostic purposes.
  if (FieldSize == 0 ||
      (AllowPadding &&
       (UnpackedFieldOffset & (UnpackedFieldAlign - 1)) + FieldSize >
           StorageUnitSize))
    UnpackedFieldOffset =
        llvm::alignTo(UnpackedFieldOffset, UnpackedFieldAlign);
  else if (ExplicitFieldAlign &&
           (MaxFieldAlignmentInBits == 0 ||
            ExplicitFieldAlign <= MaxFieldAlignmentInBits) &&
           Context.getTargetInfo().useExplicitBitFieldAlignment())
    UnpackedFieldOffset =
        llvm::alignTo(UnpackedFieldOffset, ExplicitFieldAlign);
}

// If we're using external layout, give the external layout a chance
// to override this information.
if (UseExternalLayout)
  FieldOffset = updateExternalFieldOffset(D, FieldOffset);

// Okay, place the bitfield at the calculated offset.
FieldOffsets.push_back(FieldOffset);

// Bookkeeping:

// Anonymous members don't affect the overall record alignment,
// except on targets where they do.
if (!IsMsStruct &&
    !Context.getTargetInfo().useZeroLengthBitfieldAlignment() &&
    !D->getIdentifier())
  FieldAlign = UnpackedFieldAlign = 1;

// On AIX, zero-width bitfields pad out to the alignment boundary, but then
// do not affect overall record alignment if there is a pragma pack or
// pragma align(packed).
if (isAIXLayout(Context) && !MaxFieldAlignment.isZero() && !FieldSize)
  FieldAlign = std::min(FieldAlign, MaxFieldAlignmentInBits);

// Diagnose differences in layout due to padding or packing.
if (!UseExternalLayout)
  CheckFieldPadding(FieldOffset, UnpaddedFieldOffset, UnpackedFieldOffset,
                    UnpackedFieldAlign, FieldPacked, D);

// Update DataSize to include the last byte containing (part of) the bitfield.

// For unions, this is just a max operation, as usual.
if (IsUnion) {
  // For ms_struct, allocate the entire storage unit --- unless this
  // is a zero-width bitfield, in which case just use a size of 1.
  uint64_t RoundedFieldSize;
  if (IsMsStruct) {
    RoundedFieldSize = (FieldSize ? StorageUnitSize
                                  : Context.getTargetInfo().getCharWidth());

    // Otherwise, allocate just the number of bytes required to store
    // the bitfield.
  } else {
    RoundedFieldSize = roundUpSizeToCharAlignment(FieldSize, Context);
  }
  setDataSize(std::max(getDataSizeInBits(), RoundedFieldSize));

// For non-zero-width bitfields in ms_struct structs, allocate a new
// storage unit if necessary.
} else if (IsMsStruct && FieldSize) {
  // We should have cleared UnfilledBitsInLastUnit in every case
  // where we changed storage units.
  if (!UnfilledBitsInLastUnit) {
    setDataSize(FieldOffset + StorageUnitSize);
    UnfilledBitsInLastUnit = StorageUnitSize;
  }
  UnfilledBitsInLastUnit -= FieldSize;
  LastBitfieldStorageUnitSize = StorageUnitSize;

  // Otherwise, bump the data size up to include the bitfield,
  // including padding up to char alignment, and then remember how
  // bits we didn't use.
} else {
  uint64_t NewSizeInBits = FieldOffset + FieldSize;
  uint64_t CharAlignment = Context.getTargetInfo().getCharAlign();
  setDataSize(llvm::alignTo(NewSizeInBits, CharAlignment));
  UnfilledBitsInLastUnit = getDataSizeInBits() - NewSizeInBits;

  // The only time we can get here for an ms_struct is if this is a
  // zero-width bitfield, which doesn't count as anything for the
  // purposes of unfilled bits.
  LastBitfieldStorageUnitSize = 0;
}

// Update the size.
setSize(std::max(getSizeInBits(), getDataSizeInBits()));

// Remember max struct/class alignment.
UnadjustedAlignment =
    std::max(UnadjustedAlignment, Context.toCharUnitsFromBits(FieldAlign));
UpdateAlignment(Context.toCharUnitsFromBits(FieldAlign),
                Context.toCharUnitsFromBits(UnpackedFieldAlign));
1842}

1844void ItaniumRecordLayoutBuilder::LayoutField(const FieldDecl *D,
                                           bool InsertExtraPadding) {
auto *FieldClass = D->getType()->getAsCXXRecordDecl();
bool PotentiallyOverlapping = D->hasAttr<NoUniqueAddressAttr>() && FieldClass;
bool IsOverlappingEmptyField =
    PotentiallyOverlapping && FieldClass->isEmpty();

CharUnits FieldOffset =
    (IsUnion || IsOverlappingEmptyField) ? CharUnits::Zero() : getDataSize();

const bool DefaultsToAIXPowerAlignment =
    Context.getTargetInfo().defaultsToAIXPowerAlignment();
bool FoundFirstNonOverlappingEmptyFieldForAIX = false;
if (DefaultsToAIXPowerAlignment && !HandledFirstNonOverlappingEmptyField) {
  assert(FieldOffset == CharUnits::Zero() &&((void)0)
         "The first non-overlapping empty field should have been handled.")((void)0);

  if (!IsOverlappingEmptyField) {
    FoundFirstNonOverlappingEmptyFieldForAIX = true;

    // We're going to handle the "first member" based on
    // `FoundFirstNonOverlappingEmptyFieldForAIX` during the current
    // invocation of this function; record it as handled for future
    // invocations (except for unions, because the current field does not
    // represent all "firsts").
    HandledFirstNonOverlappingEmptyField = !IsUnion;
  }
}

if (D->isBitField()) {
  LayoutBitField(D);
  return;
}

uint64_t UnpaddedFieldOffset = getDataSizeInBits() - UnfilledBitsInLastUnit;
// Reset the unfilled bits.
UnfilledBitsInLastUnit = 0;
LastBitfieldStorageUnitSize = 0;

bool FieldPacked = Packed || D->hasAttr<PackedAttr>();

bool AlignIsRequired = false;
CharUnits FieldSize;
CharUnits FieldAlign;
// The amount of this class's dsize occupied by the field.
// This is equal to FieldSize unless we're permitted to pack
// into the field's tail padding.
CharUnits EffectiveFieldSize;

auto setDeclInfo = [&](bool IsIncompleteArrayType) {
  auto TI = Context.getTypeInfoInChars(D->getType());
  FieldAlign = TI.Align;
  // Flexible array members don't have any size, but they have to be
  // aligned appropriately for their element type.
  EffectiveFieldSize = FieldSize =
      IsIncompleteArrayType ? CharUnits::Zero() : TI.Width;
  AlignIsRequired = TI.AlignIsRequired;
};

if (D->getType()->isIncompleteArrayType()) {
  setDeclInfo(true /* IsIncompleteArrayType */);
} else if (const ReferenceType *RT = D->getType()->getAs<ReferenceType>()) {
  unsigned AS = Context.getTargetAddressSpace(RT->getPointeeType());
  EffectiveFieldSize = FieldSize = Context.toCharUnitsFromBits(
      Context.getTargetInfo().getPointerWidth(AS));
  FieldAlign = Context.toCharUnitsFromBits(
      Context.getTargetInfo().getPointerAlign(AS));
} else {
  setDeclInfo(false /* IsIncompleteArrayType */);

  // A potentially-overlapping field occupies its dsize or nvsize, whichever
  // is larger.
  if (PotentiallyOverlapping) {
    const ASTRecordLayout &Layout = Context.getASTRecordLayout(FieldClass);
    EffectiveFieldSize =
        std::max(Layout.getNonVirtualSize(), Layout.getDataSize());
  }

  if (IsMsStruct) {
    // If MS bitfield layout is required, figure out what type is being
    // laid out and align the field to the width of that type.

    // Resolve all typedefs down to their base type and round up the field
    // alignment if necessary.
    QualType T = Context.getBaseElementType(D->getType());
    if (const BuiltinType *BTy = T->getAs<BuiltinType>()) {
      CharUnits TypeSize = Context.getTypeSizeInChars(BTy);

      if (!llvm::isPowerOf2_64(TypeSize.getQuantity())) {
        assert(((void)0)
            !Context.getTargetInfo().getTriple().isWindowsMSVCEnvironment() &&((void)0)
            "Non PowerOf2 size in MSVC mode")((void)0);
        // Base types with sizes that aren't a power of two don't work
        // with the layout rules for MS structs. This isn't an issue in
        // MSVC itself since there are no such base data types there.
        // On e.g. x86_32 mingw and linux, long double is 12 bytes though.
        // Any structs involving that data type obviously can't be ABI
        // compatible with MSVC regardless of how it is laid out.

        // Since ms_struct can be mass enabled (via a pragma or via the
        // -mms-bitfields command line parameter), this can trigger for
        // structs that don't actually need MSVC compatibility, so we
        // need to be able to sidestep the ms_struct layout for these types.

        // Since the combination of -mms-bitfields together with structs
        // like max_align_t (which contains a long double) for mingw is
        // quite comon (and GCC handles it silently), just handle it
        // silently there. For other targets that have ms_struct enabled
        // (most probably via a pragma or attribute), trigger a diagnostic
        // that defaults to an error.
        if (!Context.getTargetInfo().getTriple().isWindowsGNUEnvironment())
          Diag(D->getLocation(), diag::warn_npot_ms_struct);
      }
      if (TypeSize > FieldAlign &&
          llvm::isPowerOf2_64(TypeSize.getQuantity()))
        FieldAlign = TypeSize;
    }
  }
}

// The AIX `power` alignment rules apply the natural alignment of the
// "first member" if it is of a floating-point data type (or is an aggregate
// whose recursively "first" member or element is such a type). The alignment
// associated with these types for subsequent members use an alignment value
// where the floating-point data type is considered to have 4-byte alignment.
//
// For the purposes of the foregoing: vtable pointers, non-empty base classes,
// and zero-width bit-fields count as prior members; members of empty class
// types marked `no_unique_address` are not considered to be prior members.
CharUnits PreferredAlign = FieldAlign;
if (DefaultsToAIXPowerAlignment && !AlignIsRequired &&
    (FoundFirstNonOverlappingEmptyFieldForAIX || IsNaturalAlign)) {
  auto performBuiltinTypeAlignmentUpgrade = [&](const BuiltinType *BTy) {
    if (BTy->getKind() == BuiltinType::Double ||
        BTy->getKind() == BuiltinType::LongDouble) {
      assert(PreferredAlign == CharUnits::fromQuantity(4) &&((void)0)
             "No need to upgrade the alignment value.")((void)0);
      PreferredAlign = CharUnits::fromQuantity(8);
    }
  };

  const Type *Ty = D->getType()->getBaseElementTypeUnsafe();
  if (const ComplexType *CTy = Ty->getAs<ComplexType>()) {
    performBuiltinTypeAlignmentUpgrade(CTy->getElementType()->castAs<BuiltinType>());
  } else if (const BuiltinType *BTy = Ty->getAs<BuiltinType>()) {
    performBuiltinTypeAlignmentUpgrade(BTy);
  } else if (const RecordType *RT = Ty->getAs<RecordType>()) {
    const RecordDecl *RD = RT->getDecl();
    assert(RD && "Expected non-null RecordDecl.")((void)0);
    const ASTRecordLayout &FieldRecord = Context.getASTRecordLayout(RD);
    PreferredAlign = FieldRecord.getPreferredAlignment();
  }
}

// The align if the field is not packed. This is to check if the attribute
// was unnecessary (-Wpacked).
CharUnits UnpackedFieldAlign =
    !DefaultsToAIXPowerAlignment ? FieldAlign : PreferredAlign;
CharUnits UnpackedFieldOffset = FieldOffset;

if (FieldPacked) {
  FieldAlign = CharUnits::One();
  PreferredAlign = CharUnits::One();
}
CharUnits MaxAlignmentInChars =
    Context.toCharUnitsFromBits(D->getMaxAlignment());
FieldAlign = std::max(FieldAlign, MaxAlignmentInChars);
PreferredAlign = std::max(PreferredAlign, MaxAlignmentInChars);
UnpackedFieldAlign = std::max(UnpackedFieldAlign, MaxAlignmentInChars);

// The maximum field alignment overrides the aligned attribute.
if (!MaxFieldAlignment.isZero()) {
  FieldAlign = std::min(FieldAlign, MaxFieldAlignment);
  PreferredAlign = std::min(PreferredAlign, MaxFieldAlignment);
  UnpackedFieldAlign = std::min(UnpackedFieldAlign, MaxFieldAlignment);
}

CharUnits AlignTo =
    !DefaultsToAIXPowerAlignment ? FieldAlign : PreferredAlign;
// Round up the current record size to the field's alignment boundary.
FieldOffset = FieldOffset.alignTo(AlignTo);
UnpackedFieldOffset = UnpackedFieldOffset.alignTo(UnpackedFieldAlign);

if (UseExternalLayout) {
  FieldOffset = Context.toCharUnitsFromBits(
      updateExternalFieldOffset(D, Context.toBits(FieldOffset)));

  if (!IsUnion && EmptySubobjects) {
    // Record the fact that we're placing a field at this offset.
    bool Allowed = EmptySubobjects->CanPlaceFieldAtOffset(D, FieldOffset);
    (void)Allowed;
    assert(Allowed && "Externally-placed field cannot be placed here")((void)0);
  }
} else {
  if (!IsUnion && EmptySubobjects) {
    // Check if we can place the field at this offset.
    while (!EmptySubobjects->CanPlaceFieldAtOffset(D, FieldOffset)) {
      // We couldn't place the field at the offset. Try again at a new offset.
      // We try offset 0 (for an empty field) and then dsize(C) onwards.
      if (FieldOffset == CharUnits::Zero() &&
          getDataSize() != CharUnits::Zero())
        FieldOffset = getDataSize().alignTo(AlignTo);
      else
        FieldOffset += AlignTo;
    }
  }
}

// Place this field at the current location.
FieldOffsets.push_back(Context.toBits(FieldOffset));

if (!UseExternalLayout)
  CheckFieldPadding(Context.toBits(FieldOffset), UnpaddedFieldOffset,
                    Context.toBits(UnpackedFieldOffset),
                    Context.toBits(UnpackedFieldAlign), FieldPacked, D);

if (InsertExtraPadding) {
  CharUnits ASanAlignment = CharUnits::fromQuantity(8);
  CharUnits ExtraSizeForAsan = ASanAlignment;
  if (FieldSize % ASanAlignment)
    ExtraSizeForAsan +=
        ASanAlignment - CharUnits::fromQuantity(FieldSize % ASanAlignment);
  EffectiveFieldSize = FieldSize = FieldSize + ExtraSizeForAsan;
}

// Reserve space for this field.
if (!IsOverlappingEmptyField) {
  uint64_t EffectiveFieldSizeInBits = Context.toBits(EffectiveFieldSize);
  if (IsUnion)
    setDataSize(std::max(getDataSizeInBits(), EffectiveFieldSizeInBits));
  else
    setDataSize(FieldOffset + EffectiveFieldSize);

  PaddedFieldSize = std::max(PaddedFieldSize, FieldOffset + FieldSize);
  setSize(std::max(getSizeInBits(), getDataSizeInBits()));
} else {
  setSize(std::max(getSizeInBits(),
                   (uint64_t)Context.toBits(FieldOffset + FieldSize)));
}

// Remember max struct/class ABI-specified alignment.
UnadjustedAlignment = std::max(UnadjustedAlignment, FieldAlign);
UpdateAlignment(FieldAlign, UnpackedFieldAlign, PreferredAlign);
2087}

2089void ItaniumRecordLayoutBuilder::FinishLayout(const NamedDecl *D) {
// In C++, records cannot be of size 0.
if (Context.getLangOpts().CPlusPlus && getSizeInBits() == 0) {
  if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D)) {
    // Compatibility with gcc requires a class (pod or non-pod)
    // which is not empty but of size 0; such as having fields of
    // array of zero-length, remains of Size 0
    if (RD->isEmpty())
      setSize(CharUnits::One());
  }
  else
    setSize(CharUnits::One());
}

// If we have any remaining field tail padding, include that in the overall
// size.
setSize(std::max(getSizeInBits(), (uint64_t)Context.toBits(PaddedFieldSize)));

// Finally, round the size of the record up to the alignment of the
// record itself.
uint64_t UnpaddedSize = getSizeInBits() - UnfilledBitsInLastUnit;
uint64_t UnpackedSizeInBits =
    llvm::alignTo(getSizeInBits(), Context.toBits(UnpackedAlignment));

uint64_t RoundedSize = llvm::alignTo(
    getSizeInBits(),
    Context.toBits(!Context.getTargetInfo().defaultsToAIXPowerAlignment()
                       ? Alignment
                       : PreferredAlignment));

if (UseExternalLayout) {
  // If we're inferring alignment, and the external size is smaller than
  // our size after we've rounded up to alignment, conservatively set the
  // alignment to 1.
  if (InferAlignment && External.Size < RoundedSize) {
    Alignment = CharUnits::One();
    PreferredAlignment = CharUnits::One();
    InferAlignment = false;
  }
  setSize(External.Size);
  return;
}

// Set the size to the final size.
setSize(RoundedSize);

unsigned CharBitNum = Context.getTargetInfo().getCharWidth();
if (const RecordDecl *RD = dyn_cast<RecordDecl>(D)) {
  // Warn if padding was introduced to the struct/class/union.
  if (getSizeInBits() > UnpaddedSize) {
    unsigned PadSize = getSizeInBits() - UnpaddedSize;
    bool InBits = true;
    if (PadSize % CharBitNum == 0) {
      PadSize = PadSize / CharBitNum;
      InBits = false;
    }
    Diag(RD->getLocation(), diag::warn_padded_struct_size)
        << Context.getTypeDeclType(RD)
        << PadSize
        << (InBits ? 1 : 0); // (byte|bit)
  }

  // Warn if we packed it unnecessarily, when the unpacked alignment is not
  // greater than the one after packing, the size in bits doesn't change and
  // the offset of each field is identical.
  if (Packed && UnpackedAlignment <= Alignment &&
      UnpackedSizeInBits == getSizeInBits() && !HasPackedField)
    Diag(D->getLocation(), diag::warn_unnecessary_packed)
        << Context.getTypeDeclType(RD);
}
2159}

2161void ItaniumRecordLayoutBuilder::UpdateAlignment(
  CharUnits NewAlignment, CharUnits UnpackedNewAlignment,
  CharUnits PreferredNewAlignment) {
// The alignment is not modified when using 'mac68k' alignment or when
// we have an externally-supplied layout that also provides overall alignment.
if (IsMac68kAlign || (UseExternalLayout && !InferAlignment))
  return;

if (NewAlignment > Alignment) {
  assert(llvm::isPowerOf2_64(NewAlignment.getQuantity()) &&((void)0)
         "Alignment not a power of 2")((void)0);
  Alignment = NewAlignment;
}

if (UnpackedNewAlignment > UnpackedAlignment) {
  assert(llvm::isPowerOf2_64(UnpackedNewAlignment.getQuantity()) &&((void)0)
         "Alignment not a power of 2")((void)0);
  UnpackedAlignment = UnpackedNewAlignment;
}

if (PreferredNewAlignment > PreferredAlignment) {
  assert(llvm::isPowerOf2_64(PreferredNewAlignment.getQuantity()) &&((void)0)
         "Alignment not a power of 2")((void)0);
  PreferredAlignment = PreferredNewAlignment;
}
2186}

2188uint64_t
2189ItaniumRecordLayoutBuilder::updateExternalFieldOffset(const FieldDecl *Field,
                                                    uint64_t ComputedOffset) {
uint64_t ExternalFieldOffset = External.getExternalFieldOffset(Field);

if (InferAlignment && ExternalFieldOffset < ComputedOffset) {
  // The externally-supplied field offset is before the field offset we
  // computed. Assume that the structure is packed.
  Alignment = CharUnits::One();
  PreferredAlignment = CharUnits::One();
  InferAlignment = false;
}

// Use the externally-supplied field offset.
return ExternalFieldOffset;
2203}

2205/// Get diagnostic %select index for tag kind for
2206/// field padding diagnostic message.
2207/// WARNING: Indexes apply to particular diagnostics only!
2208///
2209/// \returns diagnostic %select index.
2210static unsigned getPaddingDiagFromTagKind(TagTypeKind Tag) {
switch (Tag) {
case TTK_Struct: return 0;
case TTK_Interface: return 1;
case TTK_Class: return 2;
default: llvm_unreachable("Invalid tag kind for field padding diagnostic!")__builtin_unreachable();
}
2217}

2219void ItaniumRecordLayoutBuilder::CheckFieldPadding(
  uint64_t Offset, uint64_t UnpaddedOffset, uint64_t UnpackedOffset,
  unsigned UnpackedAlign, bool isPacked, const FieldDecl *D) {
// We let objc ivars without warning, objc interfaces generally are not used
// for padding tricks.
if (isa<ObjCIvarDecl>(D))
  return;

// Don't warn about structs created without a SourceLocation.  This can
// be done by clients of the AST, such as codegen.
if (D->getLocation().isInvalid())
  return;

unsigned CharBitNum = Context.getTargetInfo().getCharWidth();

// Warn if padding was introduced to the struct/class.
if (!IsUnion && Offset > UnpaddedOffset) {
  unsigned PadSize = Offset - UnpaddedOffset;
  bool InBits = true;
  if (PadSize % CharBitNum == 0) {
    PadSize = PadSize / CharBitNum;
    InBits = false;
  }
  if (D->getIdentifier())
    Diag(D->getLocation(), diag::warn_padded_struct_field)
        << getPaddingDiagFromTagKind(D->getParent()->getTagKind())
        << Context.getTypeDeclType(D->getParent())
        << PadSize
        << (InBits ? 1 : 0) // (byte|bit)
        << D->getIdentifier();
  else
    Diag(D->getLocation(), diag::warn_padded_struct_anon_field)
        << getPaddingDiagFromTagKind(D->getParent()->getTagKind())
        << Context.getTypeDeclType(D->getParent())
        << PadSize
        << (InBits ? 1 : 0); // (byte|bit)
}
if (isPacked && Offset != UnpackedOffset) {
 HasPackedField = true;
}
2259}

2261static const CXXMethodDecl *computeKeyFunction(ASTContext &Context,
                                             const CXXRecordDecl *RD) {
// If a class isn't polymorphic it doesn't have a key function.
if (!RD->isPolymorphic())
  return nullptr;

// A class that is not externally visible doesn't have a key function. (Or
// at least, there's no point to assigning a key function to such a class;
// this doesn't affect the ABI.)
if (!RD->isExternallyVisible())
  return nullptr;

// Template instantiations don't have key functions per Itanium C++ ABI 5.2.6.
// Same behavior as GCC.
TemplateSpecializationKind TSK = RD->getTemplateSpecializationKind();
if (TSK == TSK_ImplicitInstantiation ||
    TSK == TSK_ExplicitInstantiationDeclaration ||
    TSK == TSK_ExplicitInstantiationDefinition)
  return nullptr;

bool allowInlineFunctions =
  Context.getTargetInfo().getCXXABI().canKeyFunctionBeInline();

for (const CXXMethodDecl *MD : RD->methods()) {
  if (!MD->isVirtual())
    continue;

  if (MD->isPure())
    continue;

  // Ignore implicit member functions, they are always marked as inline, but
  // they don't have a body until they're defined.
  if (MD->isImplicit())
    continue;

  if (MD->isInlineSpecified() || MD->isConstexpr())
    continue;

  if (MD->hasInlineBody())
    continue;

  // Ignore inline deleted or defaulted functions.
  if (!MD->isUserProvided())
    continue;

  // In certain ABIs, ignore functions with out-of-line inline definitions.
  if (!allowInlineFunctions) {
    const FunctionDecl *Def;
    if (MD->hasBody(Def) && Def->isInlineSpecified())
      continue;
  }

  if (Context.getLangOpts().CUDA) {
    // While compiler may see key method in this TU, during CUDA
    // compilation we should ignore methods that are not accessible
    // on this side of compilation.
    if (Context.getLangOpts().CUDAIsDevice) {
      // In device mode ignore methods without __device__ attribute.
      if (!MD->hasAttr<CUDADeviceAttr>())
        continue;
    } else {
      // In host mode ignore __device__-only methods.
      if (!MD->hasAttr<CUDAHostAttr>() && MD->hasAttr<CUDADeviceAttr>())
        continue;
    }
  }

  // If the key function is dllimport but the class isn't, then the class has
  // no key function. The DLL that exports the key function won't export the
  // vtable in this case.
  if (MD->hasAttr<DLLImportAttr>() && !RD->hasAttr<DLLImportAttr>() &&
      !Context.getTargetInfo().hasPS4DLLImportExport())
    return nullptr;

  // We found it.
  return MD;
}

return nullptr;
2340}

2342DiagnosticBuilder ItaniumRecordLayoutBuilder::Diag(SourceLocation Loc,
                                                 unsigned DiagID) {
return Context.getDiagnostics().Report(Loc, DiagID);
2345}

2347/// Does the target C++ ABI require us to skip over the tail-padding
2348/// of the given class (considering it as a base class) when allocating
2349/// objects?
2350static bool mustSkipTailPadding(TargetCXXABI ABI, const CXXRecordDecl *RD) {
switch (ABI.getTailPaddingUseRules()) {
case TargetCXXABI::AlwaysUseTailPadding:
  return false;

case TargetCXXABI::UseTailPaddingUnlessPOD03:
  // FIXME: To the extent that this is meant to cover the Itanium ABI
  // rules, we should implement the restrictions about over-sized
  // bitfields:
  //
  // http://itanium-cxx-abi.github.io/cxx-abi/abi.html#POD :
  //   In general, a type is considered a POD for the purposes of
  //   layout if it is a POD type (in the sense of ISO C++
  //   [basic.types]). However, a POD-struct or POD-union (in the
  //   sense of ISO C++ [class]) with a bitfield member whose
  //   declared width is wider than the declared type of the
  //   bitfield is not a POD for the purpose of layout.  Similarly,
  //   an array type is not a POD for the purpose of layout if the
  //   element type of the array is not a POD for the purpose of
  //   layout.
  //
  //   Where references to the ISO C++ are made in this paragraph,
  //   the Technical Corrigendum 1 version of the standard is
  //   intended.
  return RD->isPOD();

case TargetCXXABI::UseTailPaddingUnlessPOD11:
  // This is equivalent to RD->getTypeForDecl().isCXX11PODType(),
  // but with a lot of abstraction penalty stripped off.  This does
  // assume that these properties are set correctly even in C++98
  // mode; fortunately, that is true because we want to assign
  // consistently semantics to the type-traits intrinsics (or at
  // least as many of them as possible).
  return RD->isTrivial() && RD->isCXX11StandardLayout();
}

llvm_unreachable("bad tail-padding use kind")__builtin_unreachable();
2387}

2389static bool isMsLayout(const ASTContext &Context) {
return Context.getTargetInfo().getCXXABI().isMicrosoft();
2391}

2393// This section contains an implementation of struct layout that is, up to the
2394// included tests, compatible with cl.exe (2013).  The layout produced is
2395// significantly different than those produced by the Itanium ABI.  Here we note
2396// the most important differences.
2397//
2398// * The alignment of bitfields in unions is ignored when computing the
2399//   alignment of the union.
2400// * The existence of zero-width bitfield that occurs after anything other than
2401//   a non-zero length bitfield is ignored.
2402// * There is no explicit primary base for the purposes of layout.  All bases
2403//   with vfptrs are laid out first, followed by all bases without vfptrs.
2404// * The Itanium equivalent vtable pointers are split into a vfptr (virtual
2405//   function pointer) and a vbptr (virtual base pointer).  They can each be
2406//   shared with a, non-virtual bases. These bases need not be the same.  vfptrs
2407//   always occur at offset 0.  vbptrs can occur at an arbitrary offset and are
2408//   placed after the lexicographically last non-virtual base.  This placement
2409//   is always before fields but can be in the middle of the non-virtual bases
2410//   due to the two-pass layout scheme for non-virtual-bases.
2411// * Virtual bases sometimes require a 'vtordisp' field that is laid out before
2412//   the virtual base and is used in conjunction with virtual overrides during
2413//   construction and destruction.  This is always a 4 byte value and is used as
2414//   an alternative to constructor vtables.
2415// * vtordisps are allocated in a block of memory with size and alignment equal
2416//   to the alignment of the completed structure (before applying __declspec(
2417//   align())).  The vtordisp always occur at the end of the allocation block,
2418//   immediately prior to the virtual base.
2419// * vfptrs are injected after all bases and fields have been laid out.  In
2420//   order to guarantee proper alignment of all fields, the vfptr injection
2421//   pushes all bases and fields back by the alignment imposed by those bases
2422//   and fields.  This can potentially add a significant amount of padding.
2423//   vfptrs are always injected at offset 0.
2424// * vbptrs are injected after all bases and fields have been laid out.  In
2425//   order to guarantee proper alignment of all fields, the vfptr injection
2426//   pushes all bases and fields back by the alignment imposed by those bases
2427//   and fields.  This can potentially add a significant amount of padding.
2428//   vbptrs are injected immediately after the last non-virtual base as
2429//   lexicographically ordered in the code.  If this site isn't pointer aligned
2430//   the vbptr is placed at the next properly aligned location.  Enough padding
2431//   is added to guarantee a fit.
2432// * The last zero sized non-virtual base can be placed at the end of the
2433//   struct (potentially aliasing another object), or may alias with the first
2434//   field, even if they are of the same type.
2435// * The last zero size virtual base may be placed at the end of the struct
2436//   potentially aliasing another object.
2437// * The ABI attempts to avoid aliasing of zero sized bases by adding padding
2438//   between bases or vbases with specific properties.  The criteria for
2439//   additional padding between two bases is that the first base is zero sized
2440//   or ends with a zero sized subobject and the second base is zero sized or
2441//   trails with a zero sized base or field (sharing of vfptrs can reorder the
2442//   layout of the so the leading base is not always the first one declared).
2443//   This rule does take into account fields that are not records, so padding
2444//   will occur even if the last field is, e.g. an int. The padding added for
2445//   bases is 1 byte.  The padding added between vbases depends on the alignment
2446//   of the object but is at least 4 bytes (in both 32 and 64 bit modes).
2447// * There is no concept of non-virtual alignment, non-virtual alignment and
2448//   alignment are always identical.
2449// * There is a distinction between alignment and required alignment.
2450//   __declspec(align) changes the required alignment of a struct.  This
2451//   alignment is _always_ obeyed, even in the presence of #pragma pack. A
2452//   record inherits required alignment from all of its fields and bases.
2453// * __declspec(align) on bitfields has the effect of changing the bitfield's
2454//   alignment instead of its required alignment.  This is the only known way
2455//   to make the alignment of a struct bigger than 8.  Interestingly enough
2456//   this alignment is also immune to the effects of #pragma pack and can be
2457//   used to create structures with large alignment under #pragma pack.
2458//   However, because it does not impact required alignment, such a structure,
2459//   when used as a field or base, will not be aligned if #pragma pack is
2460//   still active at the time of use.
2461//
2462// Known incompatibilities:
2463// * all: #pragma pack between fields in a record
2464// * 2010 and back: If the last field in a record is a bitfield, every object
2465//   laid out after the record will have extra padding inserted before it.  The
2466//   extra padding will have size equal to the size of the storage class of the
2467//   bitfield.  0 sized bitfields don't exhibit this behavior and the extra
2468//   padding can be avoided by adding a 0 sized bitfield after the non-zero-
2469//   sized bitfield.
2470// * 2012 and back: In 64-bit mode, if the alignment of a record is 16 or
2471//   greater due to __declspec(align()) then a second layout phase occurs after
2472//   The locations of the vf and vb pointers are known.  This layout phase
2473//   suffers from the "last field is a bitfield" bug in 2010 and results in
2474//   _every_ field getting padding put in front of it, potentially including the
2475//   vfptr, leaving the vfprt at a non-zero location which results in a fault if
2476//   anything tries to read the vftbl.  The second layout phase also treats
2477//   bitfields as separate entities and gives them each storage rather than
2478//   packing them.  Additionally, because this phase appears to perform a
2479//   (an unstable) sort on the members before laying them out and because merged
2480//   bitfields have the same address, the bitfields end up in whatever order
2481//   the sort left them in, a behavior we could never hope to replicate.

2483namespace {
2484struct MicrosoftRecordLayoutBuilder {
struct ElementInfo {
  CharUnits Size;
  CharUnits Alignment;
};
typedef llvm::DenseMap<const CXXRecordDecl *, CharUnits> BaseOffsetsMapTy;
MicrosoftRecordLayoutBuilder(const ASTContext &Context) : Context(Context) {}
2491private:
MicrosoftRecordLayoutBuilder(const MicrosoftRecordLayoutBuilder &) = delete;
void operator=(const MicrosoftRecordLayoutBuilder &) = delete;
2494public:
void layout(const RecordDecl *RD);
void cxxLayout(const CXXRecordDecl *RD);
/// Initializes size and alignment and honors some flags.
void initializeLayout(const RecordDecl *RD);
/// Initialized C++ layout, compute alignment and virtual alignment and
/// existence of vfptrs and vbptrs.  Alignment is needed before the vfptr is
/// laid out.
void initializeCXXLayout(const CXXRecordDecl *RD);
void layoutNonVirtualBases(const CXXRecordDecl *RD);
void layoutNonVirtualBase(const CXXRecordDecl *RD,
                          const CXXRecordDecl *BaseDecl,
                          const ASTRecordLayout &BaseLayout,
                          const ASTRecordLayout *&PreviousBaseLayout);
void injectVFPtr(const CXXRecordDecl *RD);
void injectVBPtr(const CXXRecordDecl *RD);
/// Lays out the fields of the record.  Also rounds size up to
/// alignment.
void layoutFields(const RecordDecl *RD);
void layoutField(const FieldDecl *FD);
void layoutBitField(const FieldDecl *FD);
/// Lays out a single zero-width bit-field in the record and handles
/// special cases associated with zero-width bit-fields.
void layoutZeroWidthBitField(const FieldDecl *FD);
void layoutVirtualBases(const CXXRecordDecl *RD);
void finalizeLayout(const RecordDecl *RD);
/// Gets the size and alignment of a base taking pragma pack and
/// __declspec(align) into account.
ElementInfo getAdjustedElementInfo(const ASTRecordLayout &Layout);
/// Gets the size and alignment of a field taking pragma  pack and
/// __declspec(align) into account.  It also updates RequiredAlignment as a
/// side effect because it is most convenient to do so here.
ElementInfo getAdjustedElementInfo(const FieldDecl *FD);
/// Places a field at an offset in CharUnits.
void placeFieldAtOffset(CharUnits FieldOffset) {
  FieldOffsets.push_back(Context.toBits(FieldOffset));
}
/// Places a bitfield at a bit offset.
void placeFieldAtBitOffset(uint64_t FieldOffset) {
  FieldOffsets.push_back(FieldOffset);
}
/// Compute the set of virtual bases for which vtordisps are required.
void computeVtorDispSet(
    llvm::SmallPtrSetImpl<const CXXRecordDecl *> &HasVtorDispSet,
    const CXXRecordDecl *RD) const;
const ASTContext &Context;
/// The size of the record being laid out.
CharUnits Size;
/// The non-virtual size of the record layout.
CharUnits NonVirtualSize;
/// The data size of the record layout.
CharUnits DataSize;
/// The current alignment of the record layout.
CharUnits Alignment;
/// The maximum allowed field alignment. This is set by #pragma pack.
CharUnits MaxFieldAlignment;
/// The alignment that this record must obey.  This is imposed by
/// __declspec(align()) on the record itself or one of its fields or bases.
CharUnits RequiredAlignment;
/// The size of the allocation of the currently active bitfield.
/// This value isn't meaningful unless LastFieldIsNonZeroWidthBitfield
/// is true.
CharUnits CurrentBitfieldSize;
/// Offset to the virtual base table pointer (if one exists).
CharUnits VBPtrOffset;
/// Minimum record size possible.
CharUnits MinEmptyStructSize;
/// The size and alignment info of a pointer.
ElementInfo PointerInfo;
/// The primary base class (if one exists).
const CXXRecordDecl *PrimaryBase;
/// The class we share our vb-pointer with.
const CXXRecordDecl *SharedVBPtrBase;
/// The collection of field offsets.
SmallVector<uint64_t, 16> FieldOffsets;
/// Base classes and their offsets in the record.
BaseOffsetsMapTy Bases;
/// virtual base classes and their offsets in the record.
ASTRecordLayout::VBaseOffsetsMapTy VBases;
/// The number of remaining bits in our last bitfield allocation.
/// This value isn't meaningful unless LastFieldIsNonZeroWidthBitfield is
/// true.
unsigned RemainingBitsInField;
bool IsUnion : 1;
/// True if the last field laid out was a bitfield and was not 0
/// width.
bool LastFieldIsNonZeroWidthBitfield : 1;
/// True if the class has its own vftable pointer.
bool HasOwnVFPtr : 1;
/// True if the class has a vbtable pointer.
bool HasVBPtr : 1;
/// True if the last sub-object within the type is zero sized or the
/// object itself is zero sized.  This *does not* count members that are not
/// records.  Only used for MS-ABI.
bool EndsWithZeroSizedObject : 1;
/// True if this class is zero sized or first base is zero sized or
/// has this property.  Only used for MS-ABI.
bool LeadsWithZeroSizedBase : 1;

/// True if the external AST source provided a layout for this record.
bool UseExternalLayout : 1;

/// The layout provided by the external AST source. Only active if
/// UseExternalLayout is true.
ExternalLayout External;
2599};
2600} // namespace

2602MicrosoftRecordLayoutBuilder::ElementInfo
2603MicrosoftRecordLayoutBuilder::getAdjustedElementInfo(
  const ASTRecordLayout &Layout) {
ElementInfo Info;
Info.Alignment = Layout.getAlignment();
// Respect pragma pack.
if (!MaxFieldAlignment.isZero())
  Info.Alignment = std::min(Info.Alignment, MaxFieldAlignment);
// Track zero-sized subobjects here where it's already available.
EndsWithZeroSizedObject = Layout.endsWithZeroSizedObject();
// Respect required alignment, this is necessary because we may have adjusted
// the alignment in the case of pragam pack.  Note that the required alignment
// doesn't actually apply to the struct alignment at this point.
Alignment = std::max(Alignment, Info.Alignment);
RequiredAlignment = std::max(RequiredAlignment, Layout.getRequiredAlignment());
Info.Alignment = std::max(Info.Alignment, Layout.getRequiredAlignment());
Info.Size = Layout.getNonVirtualSize();
return Info;
2620}

2622MicrosoftRecordLayoutBuilder::ElementInfo
2623MicrosoftRecordLayoutBuilder::getAdjustedElementInfo(
  const FieldDecl *FD) {
// Get the alignment of the field type's natural alignment, ignore any
// alignment attributes.
auto TInfo =
    Context.getTypeInfoInChars(FD->getType()->getUnqualifiedDesugaredType());
ElementInfo Info{TInfo.Width, TInfo.Align};
// Respect align attributes on the field.
CharUnits FieldRequiredAlignment =
    Context.toCharUnitsFromBits(FD->getMaxAlignment());
// Respect align attributes on the type.
if (Context.isAlignmentRequired(FD->getType()))
  FieldRequiredAlignment = std::max(
      Context.getTypeAlignInChars(FD->getType()), FieldRequiredAlignment);
// Respect attributes applied to subobjects of the field.
if (FD->isBitField())
  // For some reason __declspec align impacts alignment rather than required
  // alignment when it is applied to bitfields.
  Info.Alignment = std::max(Info.Alignment, FieldRequiredAlignment);
else {
  if (auto RT =
          FD->getType()->getBaseElementTypeUnsafe()->getAs<RecordType>()) {
    auto const &Layout = Context.getASTRecordLayout(RT->getDecl());
    EndsWithZeroSizedObject = Layout.endsWithZeroSizedObject();
    FieldRequiredAlignment = std::max(FieldRequiredAlignment,
                                      Layout.getRequiredAlignment());
  }
  // Capture required alignment as a side-effect.
  RequiredAlignment = std::max(RequiredAlignment, FieldRequiredAlignment);
}
// Respect pragma pack, attribute pack and declspec align
if (!MaxFieldAlignment.isZero())
  Info.Alignment = std::min(Info.Alignment, MaxFieldAlignment);
if (FD->hasAttr<PackedAttr>())
  Info.Alignment = CharUnits::One();
Info.Alignment = std::max(Info.Alignment, FieldRequiredAlignment);
return Info;
2660}

2662void MicrosoftRecordLayoutBuilder::layout(const RecordDecl *RD) {
// For C record layout, zero-sized records always have size 4.
MinEmptyStructSize = CharUnits::fromQuantity(4);
initializeLayout(RD);
layoutFields(RD);
DataSize = Size = Size.alignTo(Alignment);
RequiredAlignment = std::max(
    RequiredAlignment, Context.toCharUnitsFromBits(RD->getMaxAlignment()));
finalizeLayout(RD);
2671}

2673void MicrosoftRecordLayoutBuilder::cxxLayout(const CXXRecordDecl *RD) {
// The C++ standard says that empty structs have size 1.
MinEmptyStructSize = CharUnits::One();
initializeLayout(RD);
initializeCXXLayout(RD);
layoutNonVirtualBases(RD);
layoutFields(RD);
injectVBPtr(RD);
injectVFPtr(RD);
if (HasOwnVFPtr || (HasVBPtr && !SharedVBPtrBase))
  Alignment = std::max(Alignment, PointerInfo.Alignment);
auto RoundingAlignment = Alignment;
if (!MaxFieldAlignment.isZero())
  RoundingAlignment = std::min(RoundingAlignment, MaxFieldAlignment);
if (!UseExternalLayout)
  Size = Size.alignTo(RoundingAlignment);
NonVirtualSize = Size;
RequiredAlignment = std::max(
    RequiredAlignment, Context.toCharUnitsFromBits(RD->getMaxAlignment()));
layoutVirtualBases(RD);
finalizeLayout(RD);
2694}

2696void MicrosoftRecordLayoutBuilder::initializeLayout(const RecordDecl *RD) {
IsUnion = RD->isUnion();
Size = CharUnits::Zero();
Alignment = CharUnits::One();
// In 64-bit mode we always perform an alignment step after laying out vbases.
// In 32-bit mode we do not.  The check to see if we need to perform alignment
// checks the RequiredAlignment field and performs alignment if it isn't 0.
RequiredAlignment = Context.getTargetInfo().getTriple().isArch64Bit()
                        ? CharUnits::One()
                        : CharUnits::Zero();
// Compute the maximum field alignment.
MaxFieldAlignment = CharUnits::Zero();
// Honor the default struct packing maximum alignment flag.
if (unsigned DefaultMaxFieldAlignment = Context.getLangOpts().PackStruct)
    MaxFieldAlignment = CharUnits::fromQuantity(DefaultMaxFieldAlignment);
// Honor the packing attribute.  The MS-ABI ignores pragma pack if its larger
// than the pointer size.
if (const MaxFieldAlignmentAttr *MFAA = RD->getAttr<MaxFieldAlignmentAttr>()){
  unsigned PackedAlignment = MFAA->getAlignment();
  if (PackedAlignment <= Context.getTargetInfo().getPointerWidth(0))
    MaxFieldAlignment = Context.toCharUnitsFromBits(PackedAlignment);
}
// Packed attribute forces max field alignment to be 1.
if (RD->hasAttr<PackedAttr>())
  MaxFieldAlignment = CharUnits::One();

// Try to respect the external layout if present.
UseExternalLayout = false;
if (ExternalASTSource *Source = Context.getExternalSource())
  UseExternalLayout = Source->layoutRecordType(
      RD, External.Size, External.Align, External.FieldOffsets,
      External.BaseOffsets, External.VirtualBaseOffsets);
2728}

2730void
2731MicrosoftRecordLayoutBuilder::initializeCXXLayout(const CXXRecordDecl *RD) {
EndsWithZeroSizedObject = false;
LeadsWithZeroSizedBase = false;
HasOwnVFPtr = false;
HasVBPtr = false;
PrimaryBase = nullptr;
SharedVBPtrBase = nullptr;
// Calculate pointer size and alignment.  These are used for vfptr and vbprt
// injection.
PointerInfo.Size =
    Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
PointerInfo.Alignment =
    Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerAlign(0));
// Respect pragma pack.
if (!MaxFieldAlignment.isZero())
  PointerInfo.Alignment = std::min(PointerInfo.Alignment, MaxFieldAlignment);
2747}

2749void
2750MicrosoftRecordLayoutBuilder::layoutNonVirtualBases(const CXXRecordDecl *RD) {
// The MS-ABI lays out all bases that contain leading vfptrs before it lays
// out any bases that do not contain vfptrs.  We implement this as two passes
// over the bases.  This approach guarantees that the primary base is laid out
// first.  We use these passes to calculate some additional aggregated
// information about the bases, such as required alignment and the presence of
// zero sized members.
const ASTRecordLayout *PreviousBaseLayout = nullptr;
bool HasPolymorphicBaseClass = false;
// Iterate through the bases and lay out the non-virtual ones.
for (const CXXBaseSpecifier &Base : RD->bases()) {
  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
  HasPolymorphicBaseClass |= BaseDecl->isPolymorphic();
  const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
  // Mark and skip virtual bases.
  if (Base.isVirtual()) {
    HasVBPtr = true;
    continue;
  }
  // Check for a base to share a VBPtr with.
  if (!SharedVBPtrBase && BaseLayout.hasVBPtr()) {
    SharedVBPtrBase = BaseDecl;
    HasVBPtr = true;
  }
  // Only lay out bases with extendable VFPtrs on the first pass.
  if (!BaseLayout.hasExtendableVFPtr())
    continue;
  // If we don't have a primary base, this one qualifies.
  if (!PrimaryBase) {
    PrimaryBase = BaseDecl;
    LeadsWithZeroSizedBase = BaseLayout.leadsWithZeroSizedBase();
  }
  // Lay out the base.
  layoutNonVirtualBase(RD, BaseDecl, BaseLayout, PreviousBaseLayout);
}
// Figure out if we need a fresh VFPtr for this class.
if (RD->isPolymorphic()) {
  if (!HasPolymorphicBaseClass)
    // This class introduces polymorphism, so we need a vftable to store the
    // RTTI information.
    HasOwnVFPtr = true;
  else if (!PrimaryBase) {
    // We have a polymorphic base class but can't extend its vftable. Add a
    // new vfptr if we would use any vftable slots.
    for (CXXMethodDecl *M : RD->methods()) {
      if (MicrosoftVTableContext::hasVtableSlot(M) &&
          M->size_overridden_methods() == 0) {
        HasOwnVFPtr = true;
        break;
      }
    }
  }
}
// If we don't have a primary base then we have a leading object that could
// itself lead with a zero-sized object, something we track.
bool CheckLeadingLayout = !PrimaryBase;
// Iterate through the bases and lay out the non-virtual ones.
for (const CXXBaseSpecifier &Base : RD->bases()) {
  if (Base.isVirtual())
    continue;
  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
  const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
  // Only lay out bases without extendable VFPtrs on the second pass.
  if (BaseLayout.hasExtendableVFPtr()) {
    VBPtrOffset = Bases[BaseDecl] + BaseLayout.getNonVirtualSize();
    continue;
  }
  // If this is the first layout, check to see if it leads with a zero sized
  // object.  If it does, so do we.
  if (CheckLeadingLayout) {
    CheckLeadingLayout = false;
    LeadsWithZeroSizedBase = BaseLayout.leadsWithZeroSizedBase();
  }
  // Lay out the base.
  layoutNonVirtualBase(RD, BaseDecl, BaseLayout, PreviousBaseLayout);
  VBPtrOffset = Bases[BaseDecl] + BaseLayout.getNonVirtualSize();
}
// Set our VBPtroffset if we know it at this point.
if (!HasVBPtr)
  VBPtrOffset = CharUnits::fromQuantity(-1);
else if (SharedVBPtrBase) {
  const ASTRecordLayout &Layout = Context.getASTRecordLayout(SharedVBPtrBase);
  VBPtrOffset = Bases[SharedVBPtrBase] + Layout.getVBPtrOffset();
}
2834}

2836static bool recordUsesEBO(const RecordDecl *RD) {
if (!isa<CXXRecordDecl>(RD))
  return false;
if (RD->hasAttr<EmptyBasesAttr>())
  return true;
if (auto *LVA = RD->getAttr<LayoutVersionAttr>())
  // TODO: Double check with the next version of MSVC.
  if (LVA->getVersion() <= LangOptions::MSVC2015)
    return false;
// TODO: Some later version of MSVC will change the default behavior of the
// compiler to enable EBO by default.  When this happens, we will need an
// additional isCompatibleWithMSVC check.
return false;
2849}

2851void MicrosoftRecordLayoutBuilder::layoutNonVirtualBase(
  const CXXRecordDecl *RD,
  const CXXRecordDecl *BaseDecl,
  const ASTRecordLayout &BaseLayout,
  const ASTRecordLayout *&PreviousBaseLayout) {
// Insert padding between two bases if the left first one is zero sized or
// contains a zero sized subobject and the right is zero sized or one leads
// with a zero sized base.
bool MDCUsesEBO = recordUsesEBO(RD);
if (PreviousBaseLayout && PreviousBaseLayout->endsWithZeroSizedObject() &&
    BaseLayout.leadsWithZeroSizedBase() && !MDCUsesEBO)
  Size++;
ElementInfo Info = getAdjustedElementInfo(BaseLayout);
CharUnits BaseOffset;

// Respect the external AST source base offset, if present.
bool FoundBase = false;
if (UseExternalLayout) {
  FoundBase = External.getExternalNVBaseOffset(BaseDecl, BaseOffset);
  if (FoundBase) {
    assert(BaseOffset >= Size && "base offset already allocated")((void)0);
    Size = BaseOffset;
  }
}

if (!FoundBase) {
  if (MDCUsesEBO && BaseDecl->isEmpty()) {
    assert(BaseLayout.getNonVirtualSize() == CharUnits::Zero())((void)0);
    BaseOffset = CharUnits::Zero();
  } else {
    // Otherwise, lay the base out at the end of the MDC.
    BaseOffset = Size = Size.alignTo(Info.Alignment);
  }
}
Bases.insert(std::make_pair(BaseDecl, BaseOffset));
Size += BaseLayout.getNonVirtualSize();
PreviousBaseLayout = &BaseLayout;
2888}

2890void MicrosoftRecordLayoutBuilder::layoutFields(const RecordDecl *RD) {
LastFieldIsNonZeroWidthBitfield = false;
for (const FieldDecl *Field : RD->fields())
  layoutField(Field);
2894}

2896void MicrosoftRecordLayoutBuilder::layoutField(const FieldDecl *FD) {
if (FD->isBitField()) {
  layoutBitField(FD);
  return;
}
LastFieldIsNonZeroWidthBitfield = false;
ElementInfo Info = getAdjustedElementInfo(FD);
Alignment = std::max(Alignment, Info.Alignment);
CharUnits FieldOffset;
if (UseExternalLayout)
  FieldOffset =
      Context.toCharUnitsFromBits(External.getExternalFieldOffset(FD));
else if (IsUnion)
  FieldOffset = CharUnits::Zero();
else
  FieldOffset = Size.alignTo(Info.Alignment);
placeFieldAtOffset(FieldOffset);
Size = std::max(Size, FieldOffset + Info.Size);
2914}

2916void MicrosoftRecordLayoutBuilder::layoutBitField(const FieldDecl *FD) {
unsigned Width = FD->getBitWidthValue(Context);
if (Width == 0) {
  layoutZeroWidthBitField(FD);
  return;
}
ElementInfo Info = getAdjustedElementInfo(FD);
// Clamp the bitfield to a containable size for the sake of being able
// to lay them out.  Sema will throw an error.
if (Width > Context.toBits(Info.Size))
  Width = Context.toBits(Info.Size);
// Check to see if this bitfield fits into an existing allocation.  Note:
// MSVC refuses to pack bitfields of formal types with different sizes
// into the same allocation.
if (!UseExternalLayout && !IsUnion && LastFieldIsNonZeroWidthBitfield &&
    CurrentBitfieldSize == Info.Size && Width <= RemainingBitsInField) {
  placeFieldAtBitOffset(Context.toBits(Size) - RemainingBitsInField);
  RemainingBitsInField -= Width;
  return;
}
LastFieldIsNonZeroWidthBitfield = true;
CurrentBitfieldSize = Info.Size;
if (UseExternalLayout) {
  auto FieldBitOffset = External.getExternalFieldOffset(FD);
  placeFieldAtBitOffset(FieldBitOffset);
  auto NewSize = Context.toCharUnitsFromBits(
      llvm::alignDown(FieldBitOffset, Context.toBits(Info.Alignment)) +
      Context.toBits(Info.Size));
  Size = std::max(Size, NewSize);
  Alignment = std::max(Alignment, Info.Alignment);
} else if (IsUnion) {
  placeFieldAtOffset(CharUnits::Zero());
  Size = std::max(Size, Info.Size);
  // TODO: Add a Sema warning that MS ignores bitfield alignment in unions.
} else {
  // Allocate a new block of memory and place the bitfield in it.
  CharUnits FieldOffset = Size.alignTo(Info.Alignment);
  placeFieldAtOffset(FieldOffset);
  Size = FieldOffset + Info.Size;
  Alignment = std::max(Alignment, Info.Alignment);
  RemainingBitsInField = Context.toBits(Info.Size) - Width;
}
2958}

2960void
2961MicrosoftRecordLayoutBuilder::layoutZeroWidthBitField(const FieldDecl *FD) {
// Zero-width bitfields are ignored unless they follow a non-zero-width
// bitfield.
if (!LastFieldIsNonZeroWidthBitfield) {
  placeFieldAtOffset(IsUnion ? CharUnits::Zero() : Size);
  // TODO: Add a Sema warning that MS ignores alignment for zero
  // sized bitfields that occur after zero-size bitfields or non-bitfields.
  return;
}
LastFieldIsNonZeroWidthBitfield = false;
ElementInfo Info = getAdjustedElementInfo(FD);
if (IsUnion) {
  placeFieldAtOffset(CharUnits::Zero());
  Size = std::max(Size, Info.Size);
  // TODO: Add a Sema warning that MS ignores bitfield alignment in unions.
} else {
  // Round up the current record size to the field's alignment boundary.
  CharUnits FieldOffset = Size.alignTo(Info.Alignment);
  placeFieldAtOffset(FieldOffset);
  Size = FieldOffset;
  Alignment = std::max(Alignment, Info.Alignment);
}
2983}

2985void MicrosoftRecordLayoutBuilder::injectVBPtr(const CXXRecordDecl *RD) {
if (!HasVBPtr || SharedVBPtrBase)
  return;
// Inject the VBPointer at the injection site.
CharUnits InjectionSite = VBPtrOffset;
// But before we do, make sure it's properly aligned.
VBPtrOffset = VBPtrOffset.alignTo(PointerInfo.Alignment);
// Determine where the first field should be laid out after the vbptr.
CharUnits FieldStart = VBPtrOffset + PointerInfo.Size;
// Shift everything after the vbptr down, unless we're using an external
// layout.
if (UseExternalLayout) {
  // It is possible that there were no fields or bases located after vbptr,
  // so the size was not adjusted before.
  if (Size < FieldStart)
    Size = FieldStart;
  return;
}
// Make sure that the amount we push the fields back by is a multiple of the
// alignment.
CharUnits Offset = (FieldStart - InjectionSite)
                       .alignTo(std::max(RequiredAlignment, Alignment));
Size += Offset;
for (uint64_t &FieldOffset : FieldOffsets)
  FieldOffset += Context.toBits(Offset);
for (BaseOffsetsMapTy::value_type &Base : Bases)
  if (Base.second >= InjectionSite)
    Base.second += Offset;
3013}

3015void MicrosoftRecordLayoutBuilder::injectVFPtr(const CXXRecordDecl *RD) {
if (!HasOwnVFPtr)
  return;
// Make sure that the amount we push the struct back by is a multiple of the
// alignment.
CharUnits Offset =
    PointerInfo.Size.alignTo(std::max(RequiredAlignment, Alignment));
// Push back the vbptr, but increase the size of the object and push back
// regular fields by the offset only if not using external record layout.
if (HasVBPtr)
  VBPtrOffset += Offset;

if (UseExternalLayout) {
  // The class may have no bases or fields, but still have a vfptr
  // (e.g. it's an interface class). The size was not correctly set before
  // in this case.
  if (FieldOffsets.empty() && Bases.empty())
    Size += Offset;
  return;
}

Size += Offset;

// If we're using an external layout, the fields offsets have already
// accounted for this adjustment.
for (uint64_t &FieldOffset : FieldOffsets)
  FieldOffset += Context.toBits(Offset);
for (BaseOffsetsMapTy::value_type &Base : Bases)
  Base.second += Offset;
3044}

3046void MicrosoftRecordLayoutBuilder::layoutVirtualBases(const CXXRecordDecl *RD) {
if (!HasVBPtr)
  return;
// Vtordisps are always 4 bytes (even in 64-bit mode)
CharUnits VtorDispSize = CharUnits::fromQuantity(4);
CharUnits VtorDispAlignment = VtorDispSize;
// vtordisps respect pragma pack.
if (!MaxFieldAlignment.isZero())
  VtorDispAlignment = std::min(VtorDispAlignment, MaxFieldAlignment);
// The alignment of the vtordisp is at least the required alignment of the
// entire record.  This requirement may be present to support vtordisp
// injection.
for (const CXXBaseSpecifier &VBase : RD->vbases()) {
  const CXXRecordDecl *BaseDecl = VBase.getType()->getAsCXXRecordDecl();
  const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
  RequiredAlignment =
      std::max(RequiredAlignment, BaseLayout.getRequiredAlignment());
}
VtorDispAlignment = std::max(VtorDispAlignment, RequiredAlignment);
// Compute the vtordisp set.
llvm::SmallPtrSet<const CXXRecordDecl *, 2> HasVtorDispSet;
computeVtorDispSet(HasVtorDispSet, RD);
// Iterate through the virtual bases and lay them out.
const ASTRecordLayout *PreviousBaseLayout = nullptr;
for (const CXXBaseSpecifier &VBase : RD->vbases()) {
  const CXXRecordDecl *BaseDecl = VBase.getType()->getAsCXXRecordDecl();
  const ASTRecordLayout &BaseLayout = Context.getASTRecordLayout(BaseDecl);
  bool HasVtordisp = HasVtorDispSet.count(BaseDecl) > 0;
  // Insert padding between two bases if the left first one is zero sized or
  // contains a zero sized subobject and the right is zero sized or one leads
  // with a zero sized base.  The padding between virtual bases is 4
  // bytes (in both 32 and 64 bits modes) and always involves rounding up to
  // the required alignment, we don't know why.
  if ((PreviousBaseLayout && PreviousBaseLayout->endsWithZeroSizedObject() &&
       BaseLayout.leadsWithZeroSizedBase() && !recordUsesEBO(RD)) ||
      HasVtordisp) {
    Size = Size.alignTo(VtorDispAlignment) + VtorDispSize;
    Alignment = std::max(VtorDispAlignment, Alignment);
  }
  // Insert the virtual base.
  ElementInfo Info = getAdjustedElementInfo(BaseLayout);
  CharUnits BaseOffset;

  // Respect the external AST source base offset, if present.
  if (UseExternalLayout) {
    if (!External.getExternalVBaseOffset(BaseDecl, BaseOffset))
      BaseOffset = Size;
  } else
    BaseOffset = Size.alignTo(Info.Alignment);

  assert(BaseOffset >= Size && "base offset already allocated")((void)0);

  VBases.insert(std::make_pair(BaseDecl,
      ASTRecordLayout::VBaseInfo(BaseOffset, HasVtordisp)));
  Size = BaseOffset + BaseLayout.getNonVirtualSize();
  PreviousBaseLayout = &BaseLayout;
}
3103}

3105void MicrosoftRecordLayoutBuilder::finalizeLayout(const RecordDecl *RD) {
// Respect required alignment.  Note that in 32-bit mode Required alignment
// may be 0 and cause size not to be updated.
DataSize = Size;
if (!RequiredAlignment.isZero()) {
  Alignment = std::max(Alignment, RequiredAlignment);
  auto RoundingAlignment = Alignment;
  if (!MaxFieldAlignment.isZero())
    RoundingAlignment = std::min(RoundingAlignment, MaxFieldAlignment);
  RoundingAlignment = std::max(RoundingAlignment, RequiredAlignment);
  Size = Size.alignTo(RoundingAlignment);
}
if (Size.isZero()) {
  if (!recordUsesEBO(RD) || !cast<CXXRecordDecl>(RD)->isEmpty()) {
    EndsWithZeroSizedObject = true;
    LeadsWithZeroSizedBase = true;
  }
  // Zero-sized structures have size equal to their alignment if a
  // __declspec(align) came into play.
  if (RequiredAlignment >= MinEmptyStructSize)
    Size = Alignment;
  else
    Size = MinEmptyStructSize;
}

if (UseExternalLayout) {
  Size = Context.toCharUnitsFromBits(External.Size);
  if (External.Align)
    Alignment = Context.toCharUnitsFromBits(External.Align);
}
3135}

3137// Recursively walks the non-virtual bases of a class and determines if any of
3138// them are in the bases with overridden methods set.
3139static bool
3140RequiresVtordisp(const llvm::SmallPtrSetImpl<const CXXRecordDecl *> &
                   BasesWithOverriddenMethods,
               const CXXRecordDecl *RD) {
if (BasesWithOverriddenMethods.count(RD))
  return true;
// If any of a virtual bases non-virtual bases (recursively) requires a
// vtordisp than so does this virtual base.
for (const CXXBaseSpecifier &Base : RD->bases())
  if (!Base.isVirtual() &&
      RequiresVtordisp(BasesWithOverriddenMethods,
                       Base.getType()->getAsCXXRecordDecl()))
    return true;
return false;
3153}

3155void MicrosoftRecordLayoutBuilder::computeVtorDispSet(
  llvm::SmallPtrSetImpl<const CXXRecordDecl *> &HasVtordispSet,
  const CXXRecordDecl *RD) const {
// /vd2 or #pragma vtordisp(2): Always use vtordisps for virtual bases with
// vftables.
if (RD->getMSVtorDispMode() == MSVtorDispMode::ForVFTable) {
  for (const CXXBaseSpecifier &Base : RD->vbases()) {
    const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
    const ASTRecordLayout &Layout = Context.getASTRecordLayout(BaseDecl);
    if (Layout.hasExtendableVFPtr())
      HasVtordispSet.insert(BaseDecl);
  }
  return;
}

// If any of our bases need a vtordisp for this type, so do we.  Check our
// direct bases for vtordisp requirements.
for (const CXXBaseSpecifier &Base : RD->bases()) {
  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
  const ASTRecordLayout &Layout = Context.getASTRecordLayout(BaseDecl);
  for (const auto &bi : Layout.getVBaseOffsetsMap())
    if (bi.second.hasVtorDisp())
      HasVtordispSet.insert(bi.first);
}
// We don't introduce any additional vtordisps if either:
// * A user declared constructor or destructor aren't declared.
// * #pragma vtordisp(0) or the /vd0 flag are in use.
if ((!RD->hasUserDeclaredConstructor() && !RD->hasUserDeclaredDestructor()) ||
    RD->getMSVtorDispMode() == MSVtorDispMode::Never)
  return;
// /vd1 or #pragma vtordisp(1): Try to guess based on whether we think it's
// possible for a partially constructed object with virtual base overrides to
// escape a non-trivial constructor.
assert(RD->getMSVtorDispMode() == MSVtorDispMode::ForVBaseOverride)((void)0);
// Compute a set of base classes which define methods we override.  A virtual
// base in this set will require a vtordisp.  A virtual base that transitively
// contains one of these bases as a non-virtual base will also require a
// vtordisp.
llvm::SmallPtrSet<const CXXMethodDecl *, 8> Work;
llvm::SmallPtrSet<const CXXRecordDecl *, 2> BasesWithOverriddenMethods;
// Seed the working set with our non-destructor, non-pure virtual methods.
for (const CXXMethodDecl *MD : RD->methods())
  if (MicrosoftVTableContext::hasVtableSlot(MD) &&
      !isa<CXXDestructorDecl>(MD) && !MD->isPure())
    Work.insert(MD);
while (!Work.empty()) {
  const CXXMethodDecl *MD = *Work.begin();
  auto MethodRange = MD->overridden_methods();
  // If a virtual method has no-overrides it lives in its parent's vtable.
  if (MethodRange.begin() == MethodRange.end())
    BasesWithOverriddenMethods.insert(MD->getParent());
  else
    Work.insert(MethodRange.begin(), MethodRange.end());
  // We've finished processing this element, remove it from the working set.
  Work.erase(MD);
}
// For each of our virtual bases, check if it is in the set of overridden
// bases or if it transitively contains a non-virtual base that is.
for (const CXXBaseSpecifier &Base : RD->vbases()) {
  const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
  if (!HasVtordispSet.count(BaseDecl) &&
      RequiresVtordisp(BasesWithOverriddenMethods, BaseDecl))
    HasVtordispSet.insert(BaseDecl);
}
3219}

3221/// getASTRecordLayout - Get or compute information about the layout of the
3222/// specified record (struct/union/class), which indicates its size and field
3223/// position information.
3224const ASTRecordLayout &
3225ASTContext::getASTRecordLayout(const RecordDecl *D) const {
// These asserts test different things.  A record has a definition
// as soon as we begin to parse the definition.  That definition is
// not a complete definition (which is what isDefinition() tests)
// until we *finish* parsing the definition.

if (D->hasExternalLexicalStorage() && !D->getDefinition())
4
←
Assuming the condition is false→
  getExternalSource()->CompleteType(const_cast<RecordDecl*>(D));

D = D->getDefinition();
assert(D && "Cannot get layout of forward declarations!")((void)0);
assert(!D->isInvalidDecl() && "Cannot get layout of invalid decl!")((void)0);
assert(D->isCompleteDefinition() && "Cannot layout type before complete!")((void)0);

// Look up this layout, if already laid out, return what we have.
// Note that we can't save a reference to the entry because this function
// is recursive.
const ASTRecordLayout *Entry = ASTRecordLayouts[D];
if (Entry) return *Entry;
5
←
Assuming 'Entry' is null→
6
←
Taking false branch→

const ASTRecordLayout *NewEntry = nullptr;

if (isMsLayout(*this)) {
7
←
Taking false branch→
  MicrosoftRecordLayoutBuilder Builder(*this);
  if (const auto *RD = dyn_cast<CXXRecordDecl>(D)) {
    Builder.cxxLayout(RD);
    NewEntry = new (*this) ASTRecordLayout(
        *this, Builder.Size, Builder.Alignment, Builder.Alignment,
        Builder.Alignment, Builder.RequiredAlignment, Builder.HasOwnVFPtr,
        Builder.HasOwnVFPtr || Builder.PrimaryBase, Builder.VBPtrOffset,
        Builder.DataSize, Builder.FieldOffsets, Builder.NonVirtualSize,
        Builder.Alignment, Builder.Alignment, CharUnits::Zero(),
        Builder.PrimaryBase, false, Builder.SharedVBPtrBase,
        Builder.EndsWithZeroSizedObject, Builder.LeadsWithZeroSizedBase,
        Builder.Bases, Builder.VBases);
  } else {
    Builder.layout(D);
    NewEntry = new (*this) ASTRecordLayout(
        *this, Builder.Size, Builder.Alignment, Builder.Alignment,
        Builder.Alignment, Builder.RequiredAlignment, Builder.Size,
        Builder.FieldOffsets);
  }
} else {
  if (const auto *RD8.1
'RD' is non-null
 = dyn_cast<CXXRecordDecl>(D)) {
8
←
Assuming 'D' is a 'CXXRecordDecl'→
9
←
Taking true branch→
    EmptySubobjectMap EmptySubobjects(*this, RD);
    ItaniumRecordLayoutBuilder Builder(*this, &EmptySubobjects);
    Builder.Layout(RD);
10
←
Calling 'ItaniumRecordLayoutBuilder::Layout'→

    // In certain situations, we are allowed to lay out objects in the
    // tail-padding of base classes.  This is ABI-dependent.
    // FIXME: this should be stored in the record layout.
    bool skipTailPadding =
        mustSkipTailPadding(getTargetInfo().getCXXABI(), RD);

    // FIXME: This should be done in FinalizeLayout.
    CharUnits DataSize =
        skipTailPadding ? Builder.getSize() : Builder.getDataSize();
    CharUnits NonVirtualSize =
        skipTailPadding ? DataSize : Builder.NonVirtualSize;
    NewEntry = new (*this) ASTRecordLayout(
        *this, Builder.getSize(), Builder.Alignment,
        Builder.PreferredAlignment, Builder.UnadjustedAlignment,
        /*RequiredAlignment : used by MS-ABI)*/
        Builder.Alignment, Builder.HasOwnVFPtr, RD->isDynamicClass(),
        CharUnits::fromQuantity(-1), DataSize, Builder.FieldOffsets,
        NonVirtualSize, Builder.NonVirtualAlignment,
        Builder.PreferredNVAlignment,
        EmptySubobjects.SizeOfLargestEmptySubobject, Builder.PrimaryBase,
        Builder.PrimaryBaseIsVirtual, nullptr, false, false, Builder.Bases,
        Builder.VBases);
  } else {
    ItaniumRecordLayoutBuilder Builder(*this, /*EmptySubobjects=*/nullptr);
    Builder.Layout(D);

    NewEntry = new (*this) ASTRecordLayout(
        *this, Builder.getSize(), Builder.Alignment,
        Builder.PreferredAlignment, Builder.UnadjustedAlignment,
        /*RequiredAlignment : used by MS-ABI)*/
        Builder.Alignment, Builder.getSize(), Builder.FieldOffsets);
  }
}

ASTRecordLayouts[D] = NewEntry;

if (getLangOpts().DumpRecordLayouts) {
  llvm::outs() << "\n*** Dumping AST Record Layout\n";
  DumpRecordLayout(D, llvm::outs(), getLangOpts().DumpRecordLayoutsSimple);
}

return *NewEntry;
3315}

3317const CXXMethodDecl *ASTContext::getCurrentKeyFunction(const CXXRecordDecl *RD) {
if (!getTargetInfo().getCXXABI().hasKeyFunctions())
  return nullptr;

assert(RD->getDefinition() && "Cannot get key function for forward decl!")((void)0);
RD = RD->getDefinition();

// Beware:
//  1) computing the key function might trigger deserialization, which might
//     invalidate iterators into KeyFunctions
//  2) 'get' on the LazyDeclPtr might also trigger deserialization and
//     invalidate the LazyDeclPtr within the map itself
LazyDeclPtr Entry = KeyFunctions[RD];
const Decl *Result =
    Entry ? Entry.get(getExternalSource()) : computeKeyFunction(*this, RD);

// Store it back if it changed.
if (Entry.isOffset() || Entry.isValid() != bool(Result))
  KeyFunctions[RD] = const_cast<Decl*>(Result);

return cast_or_null<CXXMethodDecl>(Result);
3338}

3340void ASTContext::setNonKeyFunction(const CXXMethodDecl *Method) {
assert(Method == Method->getFirstDecl() &&((void)0)
       "not working with method declaration from class definition")((void)0);

// Look up the cache entry.  Since we're working with the first
// declaration, its parent must be the class definition, which is
// the correct key for the KeyFunctions hash.
const auto &Map = KeyFunctions;
auto I = Map.find(Method->getParent());

// If it's not cached, there's nothing to do.
if (I == Map.end()) return;

// If it is cached, check whether it's the target method, and if so,
// remove it from the cache. Note, the call to 'get' might invalidate
// the iterator and the LazyDeclPtr object within the map.
LazyDeclPtr Ptr = I->second;
if (Ptr.get(getExternalSource()) == Method) {
  // FIXME: remember that we did this for module / chained PCH state?
  KeyFunctions.erase(Method->getParent());
}
3361}

3363static uint64_t getFieldOffset(const ASTContext &C, const FieldDecl *FD) {
const ASTRecordLayout &Layout = C.getASTRecordLayout(FD->getParent());
return Layout.getFieldOffset(FD->getFieldIndex());
3366}

3368uint64_t ASTContext::getFieldOffset(const ValueDecl *VD) const {
uint64_t OffsetInBits;
if (const FieldDecl *FD = dyn_cast<FieldDecl>(VD)) {
  OffsetInBits = ::getFieldOffset(*this, FD);
} else {
  const IndirectFieldDecl *IFD = cast<IndirectFieldDecl>(VD);

  OffsetInBits = 0;
  for (const NamedDecl *ND : IFD->chain())
    OffsetInBits += ::getFieldOffset(*this, cast<FieldDecl>(ND));
}

return OffsetInBits;
3381}

3383uint64_t ASTContext::lookupFieldBitOffset(const ObjCInterfaceDecl *OID,
                                        const ObjCImplementationDecl *ID,
                                        const ObjCIvarDecl *Ivar) const {
const ObjCInterfaceDecl *Container = Ivar->getContainingInterface();

// FIXME: We should eliminate the need to have ObjCImplementationDecl passed
// in here; it should never be necessary because that should be the lexical
// decl context for the ivar.

// If we know have an implementation (and the ivar is in it) then
// look up in the implementation layout.
const ASTRecordLayout *RL;
if (ID && declaresSameEntity(ID->getClassInterface(), Container))
  RL = &getASTObjCImplementationLayout(ID);
else
  RL = &getASTObjCInterfaceLayout(Container);

// Compute field index.
//
// FIXME: The index here is closely tied to how ASTContext::getObjCLayout is
// implemented. This should be fixed to get the information from the layout
// directly.
unsigned Index = 0;

for (const ObjCIvarDecl *IVD = Container->all_declared_ivar_begin();
     IVD; IVD = IVD->getNextIvar()) {
  if (Ivar == IVD)
    break;
  ++Index;
}
assert(Index < RL->getFieldCount() && "Ivar is not inside record layout!")((void)0);

return RL->getFieldOffset(Index);
3416}

3418/// getObjCLayout - Get or compute information about the layout of the
3419/// given interface.
3420///
3421/// \param Impl - If given, also include the layout of the interface's
3422/// implementation. This may differ by including synthesized ivars.
3423const ASTRecordLayout &
3424ASTContext::getObjCLayout(const ObjCInterfaceDecl *D,
                        const ObjCImplementationDecl *Impl) const {
// Retrieve the definition
if (D->hasExternalLexicalStorage() && !D->getDefinition())
  getExternalSource()->CompleteType(const_cast<ObjCInterfaceDecl*>(D));
D = D->getDefinition();
assert(D && !D->isInvalidDecl() && D->isThisDeclarationADefinition() &&((void)0)
       "Invalid interface decl!")((void)0);

// Look up this layout, if already laid out, return what we have.
const ObjCContainerDecl *Key =
  Impl ? (const ObjCContainerDecl*) Impl : (const ObjCContainerDecl*) D;
if (const ASTRecordLayout *Entry = ObjCLayouts[Key])
  return *Entry;

// Add in synthesized ivar count if laying out an implementation.
if (Impl) {
  unsigned SynthCount = CountNonClassIvars(D);
  // If there aren't any synthesized ivars then reuse the interface
  // entry. Note we can't cache this because we simply free all
  // entries later; however we shouldn't look up implementations
  // frequently.
  if (SynthCount == 0)
    return getObjCLayout(D, nullptr);
}

ItaniumRecordLayoutBuilder Builder(*this, /*EmptySubobjects=*/nullptr);
Builder.Layout(D);

const ASTRecordLayout *NewEntry = new (*this) ASTRecordLayout(
    *this, Builder.getSize(), Builder.Alignment, Builder.PreferredAlignment,
    Builder.UnadjustedAlignment,
    /*RequiredAlignment : used by MS-ABI)*/
    Builder.Alignment, Builder.getDataSize(), Builder.FieldOffsets);

ObjCLayouts[Key] = NewEntry;

return *NewEntry;
3462}

3464static void PrintOffset(raw_ostream &OS,
                      CharUnits Offset, unsigned IndentLevel) {
OS << llvm::format("%10" PRId64"lld" " | ", (int64_t)Offset.getQuantity());
OS.indent(IndentLevel * 2);
3468}

3470static void PrintBitFieldOffset(raw_ostream &OS, CharUnits Offset,
                              unsigned Begin, unsigned Width,
                              unsigned IndentLevel) {
llvm::SmallString<10> Buffer;
{
  llvm::raw_svector_ostream BufferOS(Buffer);
  BufferOS << Offset.getQuantity() << ':';
  if (Width == 0) {
    BufferOS << '-';
  } else {
    BufferOS << Begin << '-' << (Begin + Width - 1);
  }
}

OS << llvm::right_justify(Buffer, 10) << " | ";
OS.indent(IndentLevel * 2);
3486}

3488static void PrintIndentNoOffset(raw_ostream &OS, unsigned IndentLevel) {
OS << "           | ";
OS.indent(IndentLevel * 2);
3491}

3493static void DumpRecordLayout(raw_ostream &OS, const RecordDecl *RD,
                           const ASTContext &C,
                           CharUnits Offset,
                           unsigned IndentLevel,
                           const char* Description,
                           bool PrintSizeInfo,
                           bool IncludeVirtualBases) {
const ASTRecordLayout &Layout = C.getASTRecordLayout(RD);
auto CXXRD = dyn_cast<CXXRecordDecl>(RD);

PrintOffset(OS, Offset, IndentLevel);
OS << C.getTypeDeclType(const_cast<RecordDecl*>(RD)).getAsString();
if (Description)
  OS << ' ' << Description;
if (CXXRD && CXXRD->isEmpty())
  OS << " (empty)";
OS << '\n';

IndentLevel++;

// Dump bases.
if (CXXRD) {
  const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
  bool HasOwnVFPtr = Layout.hasOwnVFPtr();
  bool HasOwnVBPtr = Layout.hasOwnVBPtr();

  // Vtable pointer.
  if (CXXRD->isDynamicClass() && !PrimaryBase && !isMsLayout(C)) {
    PrintOffset(OS, Offset, IndentLevel);
    OS << '(' << *RD << " vtable pointer)\n";
  } else if (HasOwnVFPtr) {
    PrintOffset(OS, Offset, IndentLevel);
    // vfptr (for Microsoft C++ ABI)
    OS << '(' << *RD << " vftable pointer)\n";
  }

  // Collect nvbases.
  SmallVector<const CXXRecordDecl *, 4> Bases;
  for (const CXXBaseSpecifier &Base : CXXRD->bases()) {
    assert(!Base.getType()->isDependentType() &&((void)0)
           "Cannot layout class with dependent bases.")((void)0);
    if (!Base.isVirtual())
      Bases.push_back(Base.getType()->getAsCXXRecordDecl());
  }

  // Sort nvbases by offset.
  llvm::stable_sort(
      Bases, [&](const CXXRecordDecl *L, const CXXRecordDecl *R) {
        return Layout.getBaseClassOffset(L) < Layout.getBaseClassOffset(R);
      });

  // Dump (non-virtual) bases
  for (const CXXRecordDecl *Base : Bases) {
    CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base);
    DumpRecordLayout(OS, Base, C, BaseOffset, IndentLevel,
                     Base == PrimaryBase ? "(primary base)" : "(base)",
                     /*PrintSizeInfo=*/false,
                     /*IncludeVirtualBases=*/false);
  }

  // vbptr (for Microsoft C++ ABI)
  if (HasOwnVBPtr) {
    PrintOffset(OS, Offset + Layout.getVBPtrOffset(), IndentLevel);
    OS << '(' << *RD << " vbtable pointer)\n";
  }
}

// Dump fields.
uint64_t FieldNo = 0;
for (RecordDecl::field_iterator I = RD->field_begin(),
       E = RD->field_end(); I != E; ++I, ++FieldNo) {
  const FieldDecl &Field = **I;
  uint64_t LocalFieldOffsetInBits = Layout.getFieldOffset(FieldNo);
  CharUnits FieldOffset =
    Offset + C.toCharUnitsFromBits(LocalFieldOffsetInBits);

  // Recursively dump fields of record type.
  if (auto RT = Field.getType()->getAs<RecordType>()) {
    DumpRecordLayout(OS, RT->getDecl(), C, FieldOffset, IndentLevel,
                     Field.getName().data(),
                     /*PrintSizeInfo=*/false,
                     /*IncludeVirtualBases=*/true);
    continue;
  }

  if (Field.isBitField()) {
    uint64_t LocalFieldByteOffsetInBits = C.toBits(FieldOffset - Offset);
    unsigned Begin = LocalFieldOffsetInBits - LocalFieldByteOffsetInBits;
    unsigned Width = Field.getBitWidthValue(C);
    PrintBitFieldOffset(OS, FieldOffset, Begin, Width, IndentLevel);
  } else {
    PrintOffset(OS, FieldOffset, IndentLevel);
  }
  const QualType &FieldType = C.getLangOpts().DumpRecordLayoutsCanonical
                                  ? Field.getType().getCanonicalType()
                                  : Field.getType();
  OS << FieldType.getAsString() << ' ' << Field << '\n';
}

// Dump virtual bases.
if (CXXRD && IncludeVirtualBases) {
  const ASTRecordLayout::VBaseOffsetsMapTy &VtorDisps =
    Layout.getVBaseOffsetsMap();

  for (const CXXBaseSpecifier &Base : CXXRD->vbases()) {
    assert(Base.isVirtual() && "Found non-virtual class!")((void)0);
    const CXXRecordDecl *VBase = Base.getType()->getAsCXXRecordDecl();

    CharUnits VBaseOffset = Offset + Layout.getVBaseClassOffset(VBase);

    if (VtorDisps.find(VBase)->second.hasVtorDisp()) {
      PrintOffset(OS, VBaseOffset - CharUnits::fromQuantity(4), IndentLevel);
      OS << "(vtordisp for vbase " << *VBase << ")\n";
    }

    DumpRecordLayout(OS, VBase, C, VBaseOffset, IndentLevel,
                     VBase == Layout.getPrimaryBase() ?
                       "(primary virtual base)" : "(virtual base)",
                     /*PrintSizeInfo=*/false,
                     /*IncludeVirtualBases=*/false);
  }
}

if (!PrintSizeInfo) return;

PrintIndentNoOffset(OS, IndentLevel - 1);
OS << "[sizeof=" << Layout.getSize().getQuantity();
if (CXXRD && !isMsLayout(C))
  OS << ", dsize=" << Layout.getDataSize().getQuantity();
OS << ", align=" << Layout.getAlignment().getQuantity();
if (C.getTargetInfo().defaultsToAIXPowerAlignment())
  OS << ", preferredalign=" << Layout.getPreferredAlignment().getQuantity();

if (CXXRD) {
  OS << ",\n";
  PrintIndentNoOffset(OS, IndentLevel - 1);
  OS << " nvsize=" << Layout.getNonVirtualSize().getQuantity();
  OS << ", nvalign=" << Layout.getNonVirtualAlignment().getQuantity();
  if (C.getTargetInfo().defaultsToAIXPowerAlignment())
    OS << ", preferrednvalign="
       << Layout.getPreferredNVAlignment().getQuantity();
}
OS << "]\n";
3636}

3638void ASTContext::DumpRecordLayout(const RecordDecl *RD, raw_ostream &OS,
                                bool Simple) const {
if (!Simple) {
1
Assuming 'Simple' is true→
2
←
Taking false branch→
  ::DumpRecordLayout(OS, RD, *this, CharUnits(), 0, nullptr,
                     /*PrintSizeInfo*/ true,
                     /*IncludeVirtualBases=*/true);
  return;
}

// The "simple" format is designed to be parsed by the
// layout-override testing code.  There shouldn't be any external
// uses of this format --- when LLDB overrides a layout, it sets up
// the data structures directly --- so feel free to adjust this as
// you like as long as you also update the rudimentary parser for it
// in libFrontend.

const ASTRecordLayout &Info = getASTRecordLayout(RD);
3
←
Calling 'ASTContext::getASTRecordLayout'→
OS << "Type: " << getTypeDeclType(RD).getAsString() << "\n";
OS << "\nLayout: ";
OS << "<ASTRecordLayout\n";
OS << "  Size:" << toBits(Info.getSize()) << "\n";
if (!isMsLayout(*this))
  OS << "  DataSize:" << toBits(Info.getDataSize()) << "\n";
OS << "  Alignment:" << toBits(Info.getAlignment()) << "\n";
if (Target->defaultsToAIXPowerAlignment())
  OS << "  PreferredAlignment:" << toBits(Info.getPreferredAlignment())
     << "\n";
OS << "  FieldOffsets: [";
for (unsigned i = 0, e = Info.getFieldCount(); i != e; ++i) {
  if (i)
    OS << ", ";
  OS << Info.getFieldOffset(i);
}
OS << "]>\n";
3672}