Add the clang library to the repo (with some of my changes, too).

1 files changed, 2488 insertions, 0 deletions

diff --git a/clang/lib/AST/RecordLayoutBuilder.cpp b/clang/lib/AST/RecordLayoutBuilder.cpp
new file mode 100644
index 0000000..c2d9294
--- /dev/null
+++ b/clang/lib/AST/RecordLayoutBuilder.cpp
@@ -0,0 +1,2488 @@
+//=== RecordLayoutBuilder.cpp - Helper class for building record layouts ---==//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/AST/Attr.h"
+#include "clang/AST/CXXInheritance.h"
+#include "clang/AST/Decl.h"
+#include "clang/AST/DeclCXX.h"
+#include "clang/AST/DeclObjC.h"
+#include "clang/AST/Expr.h"
+#include "clang/AST/RecordLayout.h"
+#include "clang/Basic/TargetInfo.h"
+#include "clang/Sema/SemaDiagnostic.h"
+#include "llvm/Support/Format.h"
+#include "llvm/ADT/SmallSet.h"
+#include "llvm/Support/MathExtras.h"
+#include "llvm/Support/CrashRecoveryContext.h"
+
+using namespace clang;
+
+namespace {
+
+/// BaseSubobjectInfo - Represents a single base subobject in a complete class.
+/// For a class hierarchy like
+///
+/// class A { };
+/// class B : A { };
+/// class C : A, B { };
+///
+/// The BaseSubobjectInfo graph for C will have three BaseSubobjectInfo
+/// instances, one for B and two for A.
+///
+/// If a base is virtual, it will only have one BaseSubobjectInfo allocated.
+struct 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;
+};
+
+/// EmptySubobjectMap - Keeps track of which empty subobjects exist at different
+/// offsets while laying out a C++ class.
+class 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 SmallVector<const CXXRecordDecl *, 1> 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);
+  void UpdateEmptyFieldSubobjects(const FieldDecl *FD, CharUnits Offset);
+  
+  /// 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 && 
+           "Field offset not at char boundary!");
+
+    return Context.toCharUnitsFromBits(FieldOffset);
+  }
+
+protected:
+  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;
+
+public:
+  /// 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);
+};
+
+void EmptySubobjectMap::ComputeEmptySubobjectSizes() {
+  // Check the bases.
+  for (CXXRecordDecl::base_class_const_iterator I = Class->bases_begin(),
+       E = Class->bases_end(); I != E; ++I) {
+    const CXXRecordDecl *BaseDecl =
+      cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
+
+    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 (CXXRecordDecl::field_iterator I = Class->field_begin(),
+       E = Class->field_end(); I != E; ++I) {
+    const FieldDecl *FD = *I;
+
+    const RecordType *RT =
+      Context.getBaseElementType(FD->getType())->getAs<RecordType>();
+
+    // We only care about record types.
+    if (!RT)
+      continue;
+
+    CharUnits EmptySize;
+    const CXXRecordDecl *MemberDecl = cast<CXXRecordDecl>(RT->getDecl());
+    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;
+  }
+}
+
+bool
+EmptySubobjectMap::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 (std::find(Classes.begin(), Classes.end(), RD) == Classes.end())
+    return true;
+
+  // There is already an empty class of the same type at this offset.
+  return false;
+}
+  
+void EmptySubobjectMap::AddSubobjectAtOffset(const CXXRecordDecl *RD, 
+                                             CharUnits Offset) {
+  // We only care about empty bases.
+  if (!RD->isEmpty())
+    return;
+
+  // If we have empty structures inside an union, we can assign both
+  // the same offset. Just avoid pushing them twice in the list.
+  ClassVectorTy& Classes = EmptyClassOffsets[Offset];
+  if (std::find(Classes.begin(), Classes.end(), RD) != Classes.end())
+    return;
+  
+  Classes.push_back(RD);
+  
+  // Update the empty class offset.
+  if (Offset > MaxEmptyClassOffset)
+    MaxEmptyClassOffset = Offset;
+}
+
+bool
+EmptySubobjectMap::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 (unsigned I = 0, E = Info->Bases.size(); I != E; ++I) {
+    BaseSubobjectInfo* Base = Info->Bases[I];
+    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) {
+    const FieldDecl *FD = *I;
+    if (FD->isBitField())
+      continue;
+  
+    CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
+    if (!CanPlaceFieldSubobjectAtOffset(FD, FieldOffset))
+      return false;
+  }
+  
+  return true;
+}
+
+void 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 (unsigned I = 0, E = Info->Bases.size(); I != E; ++I) {
+    BaseSubobjectInfo* Base = Info->Bases[I];
+    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) {
+    const FieldDecl *FD = *I;
+    if (FD->isBitField())
+      continue;
+
+    CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
+    UpdateEmptyFieldSubobjects(FD, FieldOffset);
+  }
+}
+
+bool 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;
+}
+
+bool
+EmptySubobjectMap::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 (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
+       E = RD->bases_end(); I != E; ++I) {
+    if (I->isVirtual())
+      continue;
+
+    const CXXRecordDecl *BaseDecl =
+      cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
+
+    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 (CXXRecordDecl::base_class_const_iterator I = RD->vbases_begin(),
+         E = RD->vbases_end(); I != E; ++I) {
+      const CXXRecordDecl *VBaseDecl =
+        cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
+      
+      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) {
+    const FieldDecl *FD = *I;
+    if (FD->isBitField())
+      continue;
+
+    CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
+    
+    if (!CanPlaceFieldSubobjectAtOffset(FD, FieldOffset))
+      return false;
+  }
+
+  return true;
+}
+
+bool
+EmptySubobjectMap::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 RecordType *RT = T->getAs<RecordType>()) {
+    const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
+    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 = cast<CXXRecordDecl>(RT->getDecl());
+    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;
+}
+
+bool
+EmptySubobjectMap::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 base subobject map.
+  UpdateEmptyFieldSubobjects(FD, Offset);
+  return true;
+}
+
+void EmptySubobjectMap::UpdateEmptyFieldSubobjects(const CXXRecordDecl *RD, 
+                                                   const CXXRecordDecl *Class,
+                                                   CharUnits Offset) {
+  // 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 (Offset >= SizeOfLargestEmptySubobject)
+    return;
+
+  AddSubobjectAtOffset(RD, Offset);
+
+  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
+
+  // Traverse all non-virtual bases.
+  for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
+       E = RD->bases_end(); I != E; ++I) {
+    if (I->isVirtual())
+      continue;
+
+    const CXXRecordDecl *BaseDecl =
+      cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
+
+    CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(BaseDecl);
+    UpdateEmptyFieldSubobjects(BaseDecl, Class, BaseOffset);
+  }
+
+  if (RD == Class) {
+    // This is the most derived class, traverse virtual bases as well.
+    for (CXXRecordDecl::base_class_const_iterator I = RD->vbases_begin(),
+         E = RD->vbases_end(); I != E; ++I) {
+      const CXXRecordDecl *VBaseDecl =
+      cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
+      
+      CharUnits VBaseOffset = Offset + Layout.getVBaseClassOffset(VBaseDecl);
+      UpdateEmptyFieldSubobjects(VBaseDecl, Class, VBaseOffset);
+    }
+  }
+  
+  // Traverse all member variables.
+  unsigned FieldNo = 0;
+  for (CXXRecordDecl::field_iterator I = RD->field_begin(), E = RD->field_end();
+       I != E; ++I, ++FieldNo) {
+    const FieldDecl *FD = *I;
+    if (FD->isBitField())
+      continue;
+
+    CharUnits FieldOffset = Offset + getFieldOffset(Layout, FieldNo);
+
+    UpdateEmptyFieldSubobjects(FD, FieldOffset);
+  }
+}
+  
+void EmptySubobjectMap::UpdateEmptyFieldSubobjects(const FieldDecl *FD,
+                                                   CharUnits Offset) {
+  QualType T = FD->getType();
+  if (const RecordType *RT = T->getAs<RecordType>()) {
+    const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
+    UpdateEmptyFieldSubobjects(RD, RD, Offset);
+    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 = cast<CXXRecordDecl>(RT->getDecl());
+    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 (ElementOffset >= SizeOfLargestEmptySubobject)
+        return;
+
+      UpdateEmptyFieldSubobjects(RD, RD, ElementOffset);
+      ElementOffset += Layout.getSize();
+    }
+  }
+}
+
+class RecordLayoutBuilder {
+protected:
+  // 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;
+
+  /// \brief The alignment if attribute packed is not used.
+  CharUnits UnpackedAlignment;
+
+  SmallVector<uint64_t, 16> FieldOffsets;
+
+  /// \brief Whether the external AST source has provided a layout for this
+  /// record.
+  unsigned ExternalLayout : 1;
+
+  /// \brief 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 IsMsStruct : 1;
+
+  /// UnfilledBitsInLastByte - If the last field laid out was a bitfield,
+  /// this contains the number of bits in the last byte that can be used for
+  /// an adjacent bitfield if necessary.
+  unsigned char UnfilledBitsInLastByte;
+
+  /// 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;
+
+  FieldDecl *ZeroLengthBitfield;
+
+  /// 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;
+
+  /// VFPtrOffset - Virtual function table offset. Only for MS layout.
+  CharUnits VFPtrOffset;
+
+  /// VBPtrOffset - Virtual base table offset. Only for MS layout.
+  CharUnits VBPtrOffset;
+
+  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.
+  BaseOffsetsMapTy 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;
+
+  /// \brief Externally-provided size.
+  uint64_t ExternalSize;
+  
+  /// \brief Externally-provided alignment.
+  uint64_t ExternalAlign;
+  
+  /// \brief Externally-provided field offsets.
+  llvm::DenseMap<const FieldDecl *, uint64_t> ExternalFieldOffsets;
+
+  /// \brief Externally-provided direct, non-virtual base offsets.
+  llvm::DenseMap<const CXXRecordDecl *, CharUnits> ExternalBaseOffsets;
+
+  /// \brief Externally-provided virtual base offsets.
+  llvm::DenseMap<const CXXRecordDecl *, CharUnits> ExternalVirtualBaseOffsets;
+
+  RecordLayoutBuilder(const ASTContext &Context,
+                      EmptySubobjectMap *EmptySubobjects)
+    : Context(Context), EmptySubobjects(EmptySubobjects), Size(0), 
+      Alignment(CharUnits::One()), UnpackedAlignment(CharUnits::One()),
+      ExternalLayout(false), InferAlignment(false), 
+      Packed(false), IsUnion(false), IsMac68kAlign(false), IsMsStruct(false),
+      UnfilledBitsInLastByte(0), MaxFieldAlignment(CharUnits::Zero()), 
+      DataSize(0), NonVirtualSize(CharUnits::Zero()), 
+      NonVirtualAlignment(CharUnits::One()), 
+      ZeroLengthBitfield(0), PrimaryBase(0), 
+      PrimaryBaseIsVirtual(false),
+      VFPtrOffset(CharUnits::fromQuantity(-1)),
+      VBPtrOffset(CharUnits::fromQuantity(-1)),
+      FirstNearlyEmptyVBase(0) { }
+
+  /// Reset this RecordLayoutBuilder to a fresh state, using the given
+  /// alignment as the initial alignment.  This is used for the
+  /// correct layout of vb-table pointers in MSVC.
+  void resetWithTargetAlignment(CharUnits TargetAlignment) {
+    const ASTContext &Context = this->Context;
+    EmptySubobjectMap *EmptySubobjects = this->EmptySubobjects;
+    this->~RecordLayoutBuilder();
+    new (this) RecordLayoutBuilder(Context, EmptySubobjects);
+    Alignment = UnpackedAlignment = TargetAlignment;
+  }
+
+  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);
+  void LayoutWideBitField(uint64_t FieldSize, uint64_t TypeSize,
+                          bool FieldPacked, const FieldDecl *D);
+  void LayoutBitField(const FieldDecl *D);
+
+  bool isMicrosoftCXXABI() const {
+    return Context.getTargetInfo().getCXXABI() == CXXABI_Microsoft;
+  }
+
+  void MSLayoutVirtualBases(const CXXRecordDecl *RD);
+
+  /// 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);
+
+  bool needsVFTable(const CXXRecordDecl *RD) const;
+  bool hasNewVirtualFunction(const CXXRecordDecl *RD) const;
+  bool isPossiblePrimaryBase(const CXXRecordDecl *Base) const;
+
+  /// 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);
+  void UpdateAlignment(CharUnits NewAlignment) {
+    UpdateAlignment(NewAlignment, NewAlignment);
+  }
+
+  /// \brief 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);
+    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);
+    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; }
+
+  RecordLayoutBuilder(const RecordLayoutBuilder&);   // DO NOT IMPLEMENT
+  void operator=(const RecordLayoutBuilder&); // DO NOT IMPLEMENT
+public:
+  static const CXXMethodDecl *ComputeKeyFunction(const CXXRecordDecl *RD);
+};
+} // end anonymous namespace
+
+void
+RecordLayoutBuilder::SelectPrimaryVBase(const CXXRecordDecl *RD) {
+  for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
+         E = RD->bases_end(); I != E; ++I) {
+    assert(!I->getType()->isDependentType() &&
+           "Cannot layout class with dependent bases.");
+
+    const CXXRecordDecl *Base =
+      cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
+
+    // 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;
+  }
+}
+
+/// DeterminePrimaryBase - Determine the primary base of the given class.
+void RecordLayoutBuilder::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 (CXXRecordDecl::base_class_const_iterator i = RD->bases_begin(),
+         e = RD->bases_end(); i != e; ++i) {
+    // Ignore virtual bases.
+    if (i->isVirtual())
+      continue;
+
+    const CXXRecordDecl *Base =
+      cast<CXXRecordDecl>(i->getType()->getAs<RecordType>()->getDecl());
+
+    if (isPossiblePrimaryBase(Base)) {
+      // We found it.
+      PrimaryBase = Base;
+      PrimaryBaseIsVirtual = false;
+      return;
+    }
+  }
+
+  // The Microsoft ABI doesn't have primary virtual bases.
+  if (isMicrosoftCXXABI()) {
+    assert(!PrimaryBase && "Should not get here with a primary base!");
+    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!");
+}
+
+BaseSubobjectInfo *
+RecordLayoutBuilder::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!");
+      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 = 0;
+  Info->PrimaryVirtualBaseInfo = 0;
+  
+  const CXXRecordDecl *PrimaryVirtualBase = 0;
+  BaseSubobjectInfo *PrimaryVirtualBaseInfo = 0;
+
+  // 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!");
+      
+      // 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 = 0;        
+        } else {
+          // We can claim this base as our primary base.
+          Info->PrimaryVirtualBaseInfo = PrimaryVirtualBaseInfo;
+          PrimaryVirtualBaseInfo->Derived = Info;
+        }
+      }
+    }
+  }
+
+  // Now go through all direct bases.
+  for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
+       E = RD->bases_end(); I != E; ++I) {
+    bool IsVirtual = I->isVirtual();
+    
+    const CXXRecordDecl *BaseDecl =
+      cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
+    
+    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 &&
+           "Did not create a primary virtual base!");
+      
+    // Claim the primary virtual base as our primary virtual base.
+    Info->PrimaryVirtualBaseInfo = PrimaryVirtualBaseInfo;
+    PrimaryVirtualBaseInfo->Derived = Info;
+  }
+  
+  return Info;
+}
+
+void RecordLayoutBuilder::ComputeBaseSubobjectInfo(const CXXRecordDecl *RD) {
+  for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
+       E = RD->bases_end(); I != E; ++I) {
+    bool IsVirtual = I->isVirtual();
+
+    const CXXRecordDecl *BaseDecl =
+      cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
+    
+    // Compute the base subobject info for this base.
+    BaseSubobjectInfo *Info = ComputeBaseSubobjectInfo(BaseDecl, IsVirtual, 0);
+
+    if (IsVirtual) {
+      // ComputeBaseInfo has already added this base for us.
+      assert(VirtualBaseInfo.count(BaseDecl) &&
+             "Did not add virtual base!");
+    } else {
+      // Add the base info to the map of non-virtual bases.
+      assert(!NonVirtualBaseInfo.count(BaseDecl) &&
+             "Non-virtual base already exists!");
+      NonVirtualBaseInfo.insert(std::make_pair(BaseDecl, Info));
+    }
+  }
+}
+
+void
+RecordLayoutBuilder::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().RoundUpToAlignment(BaseAlign));
+  setDataSize(getSize());
+
+  // Update the alignment.
+  UpdateAlignment(BaseAlign, UnpackedBaseAlign);
+}
+
+void
+RecordLayoutBuilder::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 = 0;
+      
+      // We have a virtual primary base, insert it as an indirect primary base.
+      IndirectPrimaryBases.insert(PrimaryBase);
+
+      assert(!VisitedVirtualBases.count(PrimaryBase) &&
+             "vbase already visited!");
+      VisitedVirtualBases.insert(PrimaryBase);
+
+      LayoutVirtualBase(PrimaryBaseInfo);
+    } else {
+      BaseSubobjectInfo *PrimaryBaseInfo = 
+        NonVirtualBaseInfo.lookup(PrimaryBase);
+      assert(PrimaryBaseInfo && 
+             "Did not find base info for non-virtual primary base!");
+
+      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 (needsVFTable(RD)) {
+    assert(DataSize == 0 && "Vtable pointer must be at offset zero!");
+    CharUnits PtrWidth = 
+      Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
+    CharUnits PtrAlign = 
+      Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerAlign(0));
+    EnsureVTablePointerAlignment(PtrAlign);
+    if (isMicrosoftCXXABI())
+      VFPtrOffset = getSize();
+    setSize(getSize() + PtrWidth);
+    setDataSize(getSize());
+  }
+
+  bool HasDirectVirtualBases = false;
+  bool HasNonVirtualBaseWithVBTable = false;
+
+  // Now lay out the non-virtual bases.
+  for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
+         E = RD->bases_end(); I != E; ++I) {
+
+    // Ignore virtual bases, but remember that we saw one.
+    if (I->isVirtual()) {
+      HasDirectVirtualBases = true;
+      continue;
+    }
+
+    const CXXRecordDecl *BaseDecl =
+      cast<CXXRecordDecl>(I->getType()->castAs<RecordType>()->getDecl());
+
+    // Remember if this base has virtual bases itself.
+    if (BaseDecl->getNumVBases())
+      HasNonVirtualBaseWithVBTable = true;
+
+    // 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!");
+
+    LayoutNonVirtualBase(BaseInfo);
+  }
+
+  // In the MS ABI, add the vb-table pointer if we need one, which is
+  // whenever we have a virtual base and we can't re-use a vb-table
+  // pointer from a non-virtual base.
+  if (isMicrosoftCXXABI() &&
+      HasDirectVirtualBases && !HasNonVirtualBaseWithVBTable) {
+    CharUnits PtrWidth = 
+      Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(0));
+    CharUnits PtrAlign = 
+      Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerAlign(0));
+
+    // MSVC potentially over-aligns the vb-table pointer by giving it
+    // the max alignment of all the non-virtual objects in the class.
+    // This is completely unnecessary, but we're not here to pass
+    // judgment.
+    //
+    // Note that we've only laid out the non-virtual bases, so on the
+    // first pass Alignment won't be set correctly here, but if the
+    // vb-table doesn't end up aligned correctly we'll come through
+    // and redo the layout from scratch with the right alignment.
+    //
+    // TODO: Instead of doing this, just lay out the fields as if the
+    // vb-table were at offset zero, then retroactively bump the field
+    // offsets up.
+    PtrAlign = std::max(PtrAlign, Alignment);
+
+    EnsureVTablePointerAlignment(PtrAlign);
+    VBPtrOffset = getSize();
+    setSize(getSize() + PtrWidth);
+    setDataSize(getSize());
+  }
+}
+
+void RecordLayoutBuilder::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!");
+  Bases.insert(std::make_pair(Base->Class, Offset));
+
+  AddPrimaryVirtualBaseOffsets(Base, Offset);
+}
+
+void
+RecordLayoutBuilder::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 && 
+           "Primary virtual base is not virtual!");
+    if (Info->PrimaryVirtualBaseInfo->Derived == Info) {
+      // Add the offset.
+      assert(!VBases.count(Info->PrimaryVirtualBaseInfo->Class) && 
+             "primary vbase offset already exists!");
+      VBases.insert(std::make_pair(Info->PrimaryVirtualBaseInfo->Class,
+                                   Offset));
+
+      // 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 (unsigned I = 0, E = Info->Bases.size(); I != E; ++I) {
+    const BaseSubobjectInfo *Base = Info->Bases[I];
+    if (Base->IsVirtual)
+      continue;
+
+    CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base->Class);
+    AddPrimaryVirtualBaseOffsets(Base, BaseOffset);
+  }
+}
+
+/// needsVFTable - Return true if this class needs a vtable or vf-table
+/// when laid out as a base class.  These are treated the same because
+/// they're both always laid out at offset zero.
+///
+/// This function assumes that the class has no primary base.
+bool RecordLayoutBuilder::needsVFTable(const CXXRecordDecl *RD) const {
+  assert(!PrimaryBase);
+
+  // In the Itanium ABI, every dynamic class needs a vtable: even if
+  // this class has no virtual functions as a base class (i.e. it's
+  // non-polymorphic or only has virtual functions from virtual
+  // bases),x it still needs a vtable to locate its virtual bases.
+  if (!isMicrosoftCXXABI())
+    return RD->isDynamicClass();
+
+  // In the MS ABI, we need a vfptr if the class has virtual functions
+  // other than those declared by its virtual bases.  The AST doesn't
+  // tell us that directly, and checking manually for virtual
+  // functions that aren't overrides is expensive, but there are
+  // some important shortcuts:
+
+  //  - Non-polymorphic classes have no virtual functions at all.
+  if (!RD->isPolymorphic()) return false;
+
+  //  - Polymorphic classes with no virtual bases must either declare
+  //    virtual functions directly or inherit them, but in the latter
+  //    case we would have a primary base.
+  if (RD->getNumVBases() == 0) return true;
+
+  return hasNewVirtualFunction(RD);
+}
+
+/// hasNewVirtualFunction - Does the given polymorphic class declare a
+/// virtual function that does not override a method from any of its
+/// base classes?
+bool 
+RecordLayoutBuilder::hasNewVirtualFunction(const CXXRecordDecl *RD) const {
+  assert(RD->isPolymorphic());
+  if (!RD->getNumBases()) 
+    return true;
+
+  for (CXXRecordDecl::method_iterator method = RD->method_begin();
+       method != RD->method_end();
+       ++method) {
+    if (method->isVirtual() && !method->size_overridden_methods()) {
+      return true;
+    }
+  }
+  return false;
+}
+
+/// isPossiblePrimaryBase - Is the given base class an acceptable
+/// primary base class?
+bool 
+RecordLayoutBuilder::isPossiblePrimaryBase(const CXXRecordDecl *Base) const {
+  // In the Itanium ABI, a class can be a primary base class if it has
+  // a vtable for any reason.
+  if (!isMicrosoftCXXABI())
+    return Base->isDynamicClass();
+
+  // In the MS ABI, a class can only be a primary base class if it
+  // provides a vf-table at a static offset.  That means it has to be
+  // non-virtual base.  The existence of a separate vb-table means
+  // that it's possible to get virtual functions only from a virtual
+  // base, which we have to guard against.
+
+  // First off, it has to have virtual functions.
+  if (!Base->isPolymorphic()) return false;
+
+  // If it has no virtual bases, then everything is at a static offset.
+  if (!Base->getNumVBases()) return true;
+
+  // Okay, just ask the base class's layout.
+  return (Context.getASTRecordLayout(Base).getVFPtrOffset()
+            != CharUnits::fromQuantity(-1));
+}
+
+void
+RecordLayoutBuilder::LayoutVirtualBases(const CXXRecordDecl *RD,
+                                        const CXXRecordDecl *MostDerivedClass) {
+  const CXXRecordDecl *PrimaryBase;
+  bool PrimaryBaseIsVirtual;
+
+  if (MostDerivedClass == RD) {
+    PrimaryBase = this->PrimaryBase;
+    PrimaryBaseIsVirtual = this->PrimaryBaseIsVirtual;
+  } else {
+    const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);
+    PrimaryBase = Layout.getPrimaryBase();
+    PrimaryBaseIsVirtual = Layout.isPrimaryBaseVirtual();
+  }
+
+  for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
+         E = RD->bases_end(); I != E; ++I) {
+    assert(!I->getType()->isDependentType() &&
+           "Cannot layout class with dependent bases.");
+
+    const CXXRecordDecl *BaseDecl =
+      cast<CXXRecordDecl>(I->getType()->castAs<RecordType>()->getDecl());
+
+    if (I->isVirtual()) {
+      if (PrimaryBase != BaseDecl || !PrimaryBaseIsVirtual) {
+        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))
+            continue;
+
+          const BaseSubobjectInfo *BaseInfo = VirtualBaseInfo.lookup(BaseDecl);
+          assert(BaseInfo && "Did not find virtual base info!");
+          LayoutVirtualBase(BaseInfo);
+        }
+      }
+    }
+
+    if (!BaseDecl->getNumVBases()) {
+      // This base isn't interesting since it doesn't have any virtual bases.
+      continue;
+    }
+
+    LayoutVirtualBases(BaseDecl, MostDerivedClass);
+  }
+}
+
+void RecordLayoutBuilder::MSLayoutVirtualBases(const CXXRecordDecl *RD) {
+
+  if (!RD->getNumVBases())
+    return;
+
+  // This is substantially simplified because there are no virtual
+  // primary bases.
+  for (CXXRecordDecl::base_class_const_iterator I = RD->vbases_begin(),
+       E = RD->vbases_end(); I != E; ++I) {
+    const CXXRecordDecl *BaseDecl = I->getType()->getAsCXXRecordDecl();
+    const BaseSubobjectInfo *BaseInfo = VirtualBaseInfo.lookup(BaseDecl);
+    assert(BaseInfo && "Did not find virtual base info!");
+    
+    LayoutVirtualBase(BaseInfo);
+  }
+}
+
+void RecordLayoutBuilder::LayoutVirtualBase(const BaseSubobjectInfo *Base) {
+  assert(!Base->Derived && "Trying to lay out a primary virtual base!");
+  
+  // Layout the base.
+  CharUnits Offset = LayoutBase(Base);
+
+  // Add its base class offset.
+  assert(!VBases.count(Base->Class) && "vbase offset already exists!");
+  VBases.insert(std::make_pair(Base->Class, Offset));
+  
+  AddPrimaryVirtualBaseOffsets(Base, Offset);
+}
+
+CharUnits RecordLayoutBuilder::LayoutBase(const BaseSubobjectInfo *Base) {
+  const ASTRecordLayout &Layout = Context.getASTRecordLayout(Base->Class);
+
+  
+  CharUnits Offset;
+  
+  // Query the external layout to see if it provides an offset.
+  bool HasExternalLayout = false;
+  if (ExternalLayout) {
+    llvm::DenseMap<const CXXRecordDecl *, CharUnits>::iterator Known;
+    if (Base->IsVirtual) {
+      Known = ExternalVirtualBaseOffsets.find(Base->Class);
+      if (Known != ExternalVirtualBaseOffsets.end()) {
+        Offset = Known->second;
+        HasExternalLayout = true;
+      }
+    } else {
+      Known = ExternalBaseOffsets.find(Base->Class);
+      if (Known != ExternalBaseOffsets.end()) {
+        Offset = Known->second;
+        HasExternalLayout = true;
+      }
+    }
+  }
+  
+  // 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()));
+
+    return CharUnits::Zero();
+  }
+
+  CharUnits UnpackedBaseAlign = Layout.getNonVirtualAlign();
+  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);
+  }
+
+  if (!HasExternalLayout) {
+    // Round up the current record size to the base's alignment boundary.
+    Offset = getDataSize().RoundUpToAlignment(BaseAlign);
+
+    // Try to place the base.
+    while (!EmptySubobjects->CanPlaceBaseAtOffset(Base, Offset))
+      Offset += BaseAlign;
+  } else {
+    bool Allowed = EmptySubobjects->CanPlaceBaseAtOffset(Base, Offset);
+    (void)Allowed;
+    assert(Allowed && "Base subobject externally placed at overlapping offset");
+  }
+  
+  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, UnpackedBaseAlign);
+
+  return Offset;
+}
+
+void RecordLayoutBuilder::InitializeLayout(const Decl *D) {
+  if (const RecordDecl *RD = dyn_cast<RecordDecl>(D))
+    IsUnion = RD->isUnion();
+
+  Packed = D->hasAttr<PackedAttr>();
+  
+  IsMsStruct = D->hasAttr<MsStructAttr>();
+
+  // 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>()) {
+    IsMac68kAlign = true;
+    MaxFieldAlignment = CharUnits::fromQuantity(2);
+    Alignment = CharUnits::fromQuantity(2);
+  } else {
+    if (const MaxFieldAlignmentAttr *MFAA = D->getAttr<MaxFieldAlignmentAttr>())
+      MaxFieldAlignment = Context.toCharUnitsFromBits(MFAA->getAlignment());
+
+    if (unsigned MaxAlign = D->getMaxAlignment())
+      UpdateAlignment(Context.toCharUnitsFromBits(MaxAlign));
+  }
+  
+  // If there is an external AST source, ask it for the various offsets.
+  if (const RecordDecl *RD = dyn_cast<RecordDecl>(D))
+    if (ExternalASTSource *External = Context.getExternalSource()) {
+      ExternalLayout = External->layoutRecordType(RD, 
+                                                  ExternalSize,
+                                                  ExternalAlign,
+                                                  ExternalFieldOffsets,
+                                                  ExternalBaseOffsets,
+                                                  ExternalVirtualBaseOffsets);
+      
+      // Update based on external alignment.
+      if (ExternalLayout) {
+        if (ExternalAlign > 0) {
+          Alignment = Context.toCharUnitsFromBits(ExternalAlign);
+          UnpackedAlignment = Alignment;
+        } else {
+          // The external source didn't have alignment information; infer it.
+          InferAlignment = true;
+        }
+      }
+    }
+}
+
+void RecordLayoutBuilder::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);
+}
+
+void RecordLayoutBuilder::Layout(const CXXRecordDecl *RD) {
+  InitializeLayout(RD);
+
+  // Lay out the vtable and the non-virtual bases.
+  LayoutNonVirtualBases(RD);
+
+  LayoutFields(RD);
+
+  NonVirtualSize = Context.toCharUnitsFromBits(
+        llvm::RoundUpToAlignment(getSizeInBits(), 
+                                 Context.getTargetInfo().getCharAlign()));
+  NonVirtualAlignment = Alignment;
+
+  if (isMicrosoftCXXABI() &&
+      NonVirtualSize != NonVirtualSize.RoundUpToAlignment(Alignment)) {
+    CharUnits AlignMember = 
+      NonVirtualSize.RoundUpToAlignment(Alignment) - NonVirtualSize;
+
+    setSize(getSize() + AlignMember);
+    setDataSize(getSize());
+
+    NonVirtualSize = Context.toCharUnitsFromBits(
+                             llvm::RoundUpToAlignment(getSizeInBits(),
+                             Context.getTargetInfo().getCharAlign()));
+
+    MSLayoutVirtualBases(RD);
+
+  } else {
+    // Lay out the virtual bases and add the primary virtual base offsets.
+    LayoutVirtualBases(RD, RD);
+  }
+
+  // Finally, round the size of the total struct up to the alignment
+  // of the struct itself.
+  FinishLayout(RD);
+
+#ifndef NDEBUG
+  // Check that we have base offsets for all bases.
+  for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
+       E = RD->bases_end(); I != E; ++I) {
+    if (I->isVirtual())
+      continue;
+
+    const CXXRecordDecl *BaseDecl =
+      cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
+
+    assert(Bases.count(BaseDecl) && "Did not find base offset!");
+  }
+
+  // And all virtual bases.
+  for (CXXRecordDecl::base_class_const_iterator I = RD->vbases_begin(),
+       E = RD->vbases_end(); I != E; ++I) {
+    const CXXRecordDecl *BaseDecl =
+      cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
+
+    assert(VBases.count(BaseDecl) && "Did not find base offset!");
+  }
+#endif
+}
+
+void RecordLayoutBuilder::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.
+    setSize(SL.getDataSize());
+    setDataSize(getSize());
+  }
+
+  InitializeLayout(D);
+  // Layout each ivar sequentially.
+  for (const ObjCIvarDecl *IVD = D->all_declared_ivar_begin(); IVD;
+       IVD = IVD->getNextIvar())
+    LayoutField(IVD);
+
+  // Finally, round the size of the total struct up to the alignment of the
+  // struct itself.
+  FinishLayout(D);
+}
+
+void RecordLayoutBuilder::LayoutFields(const RecordDecl *D) {
+  // Layout each field, for now, just sequentially, respecting alignment.  In
+  // the future, this will need to be tweakable by targets.
+  const FieldDecl *LastFD = 0;
+  ZeroLengthBitfield = 0;
+  unsigned RemainingInAlignment = 0;
+  for (RecordDecl::field_iterator Field = D->field_begin(),
+       FieldEnd = D->field_end(); Field != FieldEnd; ++Field) {
+    if (IsMsStruct) {
+      FieldDecl *FD =  (*Field);
+      if (Context.ZeroBitfieldFollowsBitfield(FD, LastFD))
+        ZeroLengthBitfield = FD;
+      // Zero-length bitfields following non-bitfield members are
+      // ignored:
+      else if (Context.ZeroBitfieldFollowsNonBitfield(FD, LastFD))
+        continue;
+      // FIXME. streamline these conditions into a simple one.
+      else if (Context.BitfieldFollowsBitfield(FD, LastFD) ||
+               Context.BitfieldFollowsNonBitfield(FD, LastFD) ||
+               Context.NonBitfieldFollowsBitfield(FD, LastFD)) {
+        // 1) Adjacent bit fields are packed into the same 1-, 2-, or
+        // 4-byte allocation unit if the integral types are the same
+        // size and if the next bit field fits into the current
+        // allocation unit without crossing the boundary imposed by the
+        // common alignment requirements of the bit fields.
+        // 2) Establish a new alignment for a bitfield following
+        // a non-bitfield if size of their types differ.
+        // 3) Establish a new alignment for a non-bitfield following
+        // a bitfield if size of their types differ.
+        std::pair<uint64_t, unsigned> FieldInfo = 
+          Context.getTypeInfo(FD->getType());
+        uint64_t TypeSize = FieldInfo.first;
+        unsigned FieldAlign = FieldInfo.second;
+        // This check is needed for 'long long' in -m32 mode.
+        if (TypeSize > FieldAlign &&
+            (Context.hasSameType(FD->getType(), 
+                                Context.UnsignedLongLongTy) 
+             ||Context.hasSameType(FD->getType(), 
+                                   Context.LongLongTy)))
+          FieldAlign = TypeSize;
+        FieldInfo = Context.getTypeInfo(LastFD->getType());
+        uint64_t TypeSizeLastFD = FieldInfo.first;
+        unsigned FieldAlignLastFD = FieldInfo.second;
+        // This check is needed for 'long long' in -m32 mode.
+        if (TypeSizeLastFD > FieldAlignLastFD &&
+            (Context.hasSameType(LastFD->getType(), 
+                                Context.UnsignedLongLongTy)
+             || Context.hasSameType(LastFD->getType(), 
+                                    Context.LongLongTy)))
+          FieldAlignLastFD = TypeSizeLastFD;
+        
+        if (TypeSizeLastFD != TypeSize) {
+          if (RemainingInAlignment &&
+              LastFD && LastFD->isBitField() &&
+              LastFD->getBitWidthValue(Context)) {
+            // If previous field was a bitfield with some remaining unfilled
+            // bits, pad the field so current field starts on its type boundary.
+            uint64_t FieldOffset = 
+            getDataSizeInBits() - UnfilledBitsInLastByte;
+            uint64_t NewSizeInBits = RemainingInAlignment + FieldOffset;
+            setDataSize(llvm::RoundUpToAlignment(NewSizeInBits,
+                                                 Context.getTargetInfo().getCharAlign()));
+            setSize(std::max(getSizeInBits(), getDataSizeInBits()));
+            RemainingInAlignment = 0;
+          }
+          
+          uint64_t UnpaddedFieldOffset = 
+            getDataSizeInBits() - UnfilledBitsInLastByte;
+          FieldAlign = std::max(FieldAlign, FieldAlignLastFD);
+          
+          // The maximum field alignment overrides the aligned attribute.
+          if (!MaxFieldAlignment.isZero()) {
+            unsigned MaxFieldAlignmentInBits = 
+              Context.toBits(MaxFieldAlignment);
+            FieldAlign = std::min(FieldAlign, MaxFieldAlignmentInBits);
+          }
+          
+          uint64_t NewSizeInBits = 
+            llvm::RoundUpToAlignment(UnpaddedFieldOffset, FieldAlign);
+          setDataSize(llvm::RoundUpToAlignment(NewSizeInBits,
+                                               Context.getTargetInfo().getCharAlign()));
+          UnfilledBitsInLastByte = getDataSizeInBits() - NewSizeInBits;
+          setSize(std::max(getSizeInBits(), getDataSizeInBits()));
+        }
+        if (FD->isBitField()) {
+          uint64_t FieldSize = FD->getBitWidthValue(Context);
+          assert (FieldSize > 0 && "LayoutFields - ms_struct layout");
+          if (RemainingInAlignment < FieldSize)
+            RemainingInAlignment = TypeSize - FieldSize;
+          else
+            RemainingInAlignment -= FieldSize;
+        }
+      }
+      else if (FD->isBitField()) {
+        uint64_t FieldSize = FD->getBitWidthValue(Context);
+        std::pair<uint64_t, unsigned> FieldInfo = 
+          Context.getTypeInfo(FD->getType());
+        uint64_t TypeSize = FieldInfo.first;
+        RemainingInAlignment = TypeSize - FieldSize;
+      }
+      LastFD = FD;
+    }
+    else if (!Context.getTargetInfo().useBitFieldTypeAlignment() &&
+             Context.getTargetInfo().useZeroLengthBitfieldAlignment()) {             
+      FieldDecl *FD =  (*Field);
+      if (FD->isBitField() && FD->getBitWidthValue(Context) == 0)
+        ZeroLengthBitfield = FD;
+    }
+    LayoutField(*Field);
+  }
+  if (IsMsStruct && RemainingInAlignment &&
+      LastFD && LastFD->isBitField() && LastFD->getBitWidthValue(Context)) {
+    // If we ended a bitfield before the full length of the type then
+    // pad the struct out to the full length of the last type.
+    uint64_t FieldOffset = 
+      getDataSizeInBits() - UnfilledBitsInLastByte;
+    uint64_t NewSizeInBits = RemainingInAlignment + FieldOffset;
+    setDataSize(llvm::RoundUpToAlignment(NewSizeInBits,
+                                         Context.getTargetInfo().getCharAlign()));
+    setSize(std::max(getSizeInBits(), getDataSizeInBits()));
+  }
+}
+
+void RecordLayoutBuilder::LayoutWideBitField(uint64_t FieldSize,
+                                             uint64_t TypeSize,
+                                             bool FieldPacked,
+                                             const FieldDecl *D) {
+  assert(Context.getLangOpts().CPlusPlus &&
+         "Can only have wide bit-fields in C++!");
+
+  // 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 (unsigned I = 0, E = llvm::array_lengthof(IntegralPODTypes);
+       I != E; ++I) {
+    uint64_t Size = Context.getTypeSize(IntegralPODTypes[I]);
+
+    if (Size > FieldSize)
+      break;
+
+    Type = IntegralPODTypes[I];
+  }
+  assert(!Type.isNull() && "Did not find a type!");
+
+  CharUnits TypeAlign = Context.getTypeAlignInChars(Type);
+
+  // We're not going to use any of the unfilled bits in the last byte.
+  UnfilledBitsInLastByte = 0;
+
+  uint64_t FieldOffset;
+  uint64_t UnpaddedFieldOffset = getDataSizeInBits() - UnfilledBitsInLastByte;
+
+  if (IsUnion) {
+    setDataSize(std::max(getDataSizeInBits(), FieldSize));
+    FieldOffset = 0;
+  } else {
+    // The bitfield is allocated starting at the next offset aligned 
+    // appropriately for T', with length n bits.
+    FieldOffset = llvm::RoundUpToAlignment(getDataSizeInBits(), 
+                                           Context.toBits(TypeAlign));
+
+    uint64_t NewSizeInBits = FieldOffset + FieldSize;
+
+    setDataSize(llvm::RoundUpToAlignment(NewSizeInBits, 
+                                         Context.getTargetInfo().getCharAlign()));
+    UnfilledBitsInLastByte = 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);
+}
+
+void RecordLayoutBuilder::LayoutBitField(const FieldDecl *D) {
+  bool FieldPacked = Packed || D->hasAttr<PackedAttr>();
+  uint64_t UnpaddedFieldOffset = getDataSizeInBits() - UnfilledBitsInLastByte;
+  uint64_t FieldOffset = IsUnion ? 0 : UnpaddedFieldOffset;
+  uint64_t FieldSize = D->getBitWidthValue(Context);
+
+  std::pair<uint64_t, unsigned> FieldInfo = Context.getTypeInfo(D->getType());
+  uint64_t TypeSize = FieldInfo.first;
+  unsigned FieldAlign = FieldInfo.second;
+  
+  // This check is needed for 'long long' in -m32 mode.
+  if (IsMsStruct && (TypeSize > FieldAlign) && 
+      (Context.hasSameType(D->getType(), 
+                           Context.UnsignedLongLongTy) 
+       || Context.hasSameType(D->getType(), Context.LongLongTy)))
+    FieldAlign = TypeSize;
+
+  if (ZeroLengthBitfield) {
+    std::pair<uint64_t, unsigned> FieldInfo;
+    unsigned ZeroLengthBitfieldAlignment;
+    if (IsMsStruct) {
+      // If a zero-length bitfield is inserted after a bitfield,
+      // and the alignment of the zero-length bitfield is
+      // greater than the member that follows it, `bar', `bar' 
+      // will be aligned as the type of the zero-length bitfield.
+      if (ZeroLengthBitfield != D) {
+        FieldInfo = Context.getTypeInfo(ZeroLengthBitfield->getType());
+        ZeroLengthBitfieldAlignment = FieldInfo.second;
+        // Ignore alignment of subsequent zero-length bitfields.
+        if ((ZeroLengthBitfieldAlignment > FieldAlign) || (FieldSize == 0))
+          FieldAlign = ZeroLengthBitfieldAlignment;
+        if (FieldSize)
+          ZeroLengthBitfield = 0;
+      }
+    } else {
+      // The alignment of a zero-length bitfield affects the alignment
+      // of the next member.  The alignment is the max of the zero 
+      // length bitfield's alignment and a target specific fixed value.
+      unsigned ZeroLengthBitfieldBoundary =
+        Context.getTargetInfo().getZeroLengthBitfieldBoundary();
+      if (ZeroLengthBitfieldBoundary > FieldAlign)
+        FieldAlign = ZeroLengthBitfieldBoundary;
+    }
+  }
+
+  if (FieldSize > TypeSize) {
+    LayoutWideBitField(FieldSize, TypeSize, FieldPacked, D);
+    return;
+  }
+
+  // The align if the field is not packed. This is to check if the attribute
+  // was unnecessary (-Wpacked).
+  unsigned UnpackedFieldAlign = FieldAlign;
+  uint64_t UnpackedFieldOffset = FieldOffset;
+  if (!Context.getTargetInfo().useBitFieldTypeAlignment() && !ZeroLengthBitfield)
+    UnpackedFieldAlign = 1;
+
+  if (FieldPacked || 
+      (!Context.getTargetInfo().useBitFieldTypeAlignment() && !ZeroLengthBitfield))
+    FieldAlign = 1;
+  FieldAlign = std::max(FieldAlign, D->getMaxAlignment());
+  UnpackedFieldAlign = std::max(UnpackedFieldAlign, D->getMaxAlignment());
+
+  // The maximum field alignment overrides the aligned attribute.
+  if (!MaxFieldAlignment.isZero() && FieldSize != 0) {
+    unsigned MaxFieldAlignmentInBits = Context.toBits(MaxFieldAlignment);
+    FieldAlign = std::min(FieldAlign, MaxFieldAlignmentInBits);
+    UnpackedFieldAlign = std::min(UnpackedFieldAlign, MaxFieldAlignmentInBits);
+  }
+
+  // Check if we need to add padding to give the field the correct alignment.
+  if (FieldSize == 0 || 
+      (MaxFieldAlignment.isZero() &&
+       (FieldOffset & (FieldAlign-1)) + FieldSize > TypeSize))
+    FieldOffset = llvm::RoundUpToAlignment(FieldOffset, FieldAlign);
+
+  if (FieldSize == 0 ||
+      (MaxFieldAlignment.isZero() &&
+       (UnpackedFieldOffset & (UnpackedFieldAlign-1)) + FieldSize > TypeSize))
+    UnpackedFieldOffset = llvm::RoundUpToAlignment(UnpackedFieldOffset,
+                                                   UnpackedFieldAlign);
+
+  // Padding members don't affect overall alignment, unless zero length bitfield
+  // alignment is enabled.
+  if (!D->getIdentifier() && !Context.getTargetInfo().useZeroLengthBitfieldAlignment())
+    FieldAlign = UnpackedFieldAlign = 1;
+
+  if (!IsMsStruct)
+    ZeroLengthBitfield = 0;
+
+  if (ExternalLayout)
+    FieldOffset = updateExternalFieldOffset(D, FieldOffset);
+
+  // Place this field at the current location.
+  FieldOffsets.push_back(FieldOffset);
+
+  if (!ExternalLayout)
+    CheckFieldPadding(FieldOffset, UnpaddedFieldOffset, UnpackedFieldOffset,
+                      UnpackedFieldAlign, FieldPacked, D);
+
+  // Update DataSize to include the last byte containing (part of) the bitfield.
+  if (IsUnion) {
+    // FIXME: I think FieldSize should be TypeSize here.
+    setDataSize(std::max(getDataSizeInBits(), FieldSize));
+  } else {
+    uint64_t NewSizeInBits = FieldOffset + FieldSize;
+
+    setDataSize(llvm::RoundUpToAlignment(NewSizeInBits, 
+                                         Context.getTargetInfo().getCharAlign()));
+    UnfilledBitsInLastByte = getDataSizeInBits() - NewSizeInBits;
+  }
+
+  // Update the size.
+  setSize(std::max(getSizeInBits(), getDataSizeInBits()));
+
+  // Remember max struct/class alignment.
+  UpdateAlignment(Context.toCharUnitsFromBits(FieldAlign), 
+                  Context.toCharUnitsFromBits(UnpackedFieldAlign));
+}
+
+void RecordLayoutBuilder::LayoutField(const FieldDecl *D) {  
+  if (D->isBitField()) {
+    LayoutBitField(D);
+    return;
+  }
+
+  uint64_t UnpaddedFieldOffset = getDataSizeInBits() - UnfilledBitsInLastByte;
+
+  // Reset the unfilled bits.
+  UnfilledBitsInLastByte = 0;
+
+  bool FieldPacked = Packed || D->hasAttr<PackedAttr>();
+  CharUnits FieldOffset = 
+    IsUnion ? CharUnits::Zero() : getDataSize();
+  CharUnits FieldSize;
+  CharUnits FieldAlign;
+
+  if (D->getType()->isIncompleteArrayType()) {
+    // This is a flexible array member; we can't directly
+    // query getTypeInfo about these, so we figure it out here.
+    // Flexible array members don't have any size, but they
+    // have to be aligned appropriately for their element type.
+    FieldSize = CharUnits::Zero();
+    const ArrayType* ATy = Context.getAsArrayType(D->getType());
+    FieldAlign = Context.getTypeAlignInChars(ATy->getElementType());
+  } else if (const ReferenceType *RT = D->getType()->getAs<ReferenceType>()) {
+    unsigned AS = RT->getPointeeType().getAddressSpace();
+    FieldSize = 
+      Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerWidth(AS));
+    FieldAlign = 
+      Context.toCharUnitsFromBits(Context.getTargetInfo().getPointerAlign(AS));
+  } else {
+    std::pair<CharUnits, CharUnits> FieldInfo = 
+      Context.getTypeInfoInChars(D->getType());
+    FieldSize = FieldInfo.first;
+    FieldAlign = FieldInfo.second;
+
+    if (ZeroLengthBitfield) {
+      CharUnits ZeroLengthBitfieldBoundary = 
+        Context.toCharUnitsFromBits(
+          Context.getTargetInfo().getZeroLengthBitfieldBoundary());
+      if (ZeroLengthBitfieldBoundary == CharUnits::Zero()) {
+        // If a zero-length bitfield is inserted after a bitfield,
+        // and the alignment of the zero-length bitfield is
+        // greater than the member that follows it, `bar', `bar' 
+        // will be aligned as the type of the zero-length bitfield.
+        std::pair<CharUnits, CharUnits> FieldInfo = 
+          Context.getTypeInfoInChars(ZeroLengthBitfield->getType());
+        CharUnits ZeroLengthBitfieldAlignment = FieldInfo.second;        
+        if (ZeroLengthBitfieldAlignment > FieldAlign)
+          FieldAlign = ZeroLengthBitfieldAlignment;
+      } else if (ZeroLengthBitfieldBoundary > FieldAlign) {
+        // Align 'bar' based on a fixed alignment specified by the target.
+        assert(Context.getTargetInfo().useZeroLengthBitfieldAlignment() &&
+               "ZeroLengthBitfieldBoundary should only be used in conjunction"
+               " with useZeroLengthBitfieldAlignment.");
+        FieldAlign = ZeroLengthBitfieldBoundary;
+      }
+      ZeroLengthBitfield = 0;
+    }
+
+    if (Context.getLangOpts().MSBitfields || 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 (TypeSize > FieldAlign)
+          FieldAlign = TypeSize;
+      }
+    }
+  }
+
+  // The align if the field is not packed. This is to check if the attribute
+  // was unnecessary (-Wpacked).
+  CharUnits UnpackedFieldAlign = FieldAlign;
+  CharUnits UnpackedFieldOffset = FieldOffset;
+
+  if (FieldPacked)
+    FieldAlign = CharUnits::One();
+  CharUnits MaxAlignmentInChars = 
+    Context.toCharUnitsFromBits(D->getMaxAlignment());
+  FieldAlign = std::max(FieldAlign, MaxAlignmentInChars);
+  UnpackedFieldAlign = std::max(UnpackedFieldAlign, MaxAlignmentInChars);
+
+  // The maximum field alignment overrides the aligned attribute.
+  if (!MaxFieldAlignment.isZero()) {
+    FieldAlign = std::min(FieldAlign, MaxFieldAlignment);
+    UnpackedFieldAlign = std::min(UnpackedFieldAlign, MaxFieldAlignment);
+  }
+
+  // Round up the current record size to the field's alignment boundary.
+  FieldOffset = FieldOffset.RoundUpToAlignment(FieldAlign);
+  UnpackedFieldOffset = 
+    UnpackedFieldOffset.RoundUpToAlignment(UnpackedFieldAlign);
+
+  if (ExternalLayout) {
+    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");      
+    }
+  } 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.
+        FieldOffset += FieldAlign;
+      }
+    }
+  }
+  
+  // Place this field at the current location.
+  FieldOffsets.push_back(Context.toBits(FieldOffset));
+
+  if (!ExternalLayout)
+    CheckFieldPadding(Context.toBits(FieldOffset), UnpaddedFieldOffset, 
+                      Context.toBits(UnpackedFieldOffset),
+                      Context.toBits(UnpackedFieldAlign), FieldPacked, D);
+
+  // Reserve space for this field.
+  uint64_t FieldSizeInBits = Context.toBits(FieldSize);
+  if (IsUnion)
+    setDataSize(std::max(getDataSizeInBits(), FieldSizeInBits));
+  else
+    setDataSize(FieldOffset + FieldSize);
+
+  // Update the size.
+  setSize(std::max(getSizeInBits(), getDataSizeInBits()));
+
+  // Remember max struct/class alignment.
+  UpdateAlignment(FieldAlign, UnpackedFieldAlign);
+}
+
+void RecordLayoutBuilder::FinishLayout(const NamedDecl *D) {
+  if (ExternalLayout) {
+    setSize(ExternalSize);
+    return;
+  }
+  
+  // 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());
+  }
+
+  // MSVC doesn't round up to the alignment of the record with virtual bases.
+  if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D)) {
+    if (isMicrosoftCXXABI() && RD->getNumVBases())
+      return;
+  }
+
+  // Finally, round the size of the record up to the alignment of the
+  // record itself.
+  uint64_t UnpaddedSize = getSizeInBits() - UnfilledBitsInLastByte;
+  uint64_t UnpackedSizeInBits = 
+    llvm::RoundUpToAlignment(getSizeInBits(), 
+                             Context.toBits(UnpackedAlignment));
+  CharUnits UnpackedSize = Context.toCharUnitsFromBits(UnpackedSizeInBits);
+  setSize(llvm::RoundUpToAlignment(getSizeInBits(), Context.toBits(Alignment)));
+
+  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)*/ << (PadSize > 1); // plural or not
+    }
+
+    // Warn if we packed it unnecessarily. If the alignment is 1 byte don't
+    // bother since there won't be alignment issues.
+    if (Packed && UnpackedAlignment > CharUnits::One() && 
+        getSize() == UnpackedSize)
+      Diag(D->getLocation(), diag::warn_unnecessary_packed)
+          << Context.getTypeDeclType(RD);
+  }
+}
+
+void RecordLayoutBuilder::UpdateAlignment(CharUnits NewAlignment,
+                                          CharUnits UnpackedNewAlignment) {
+  // The alignment is not modified when using 'mac68k' alignment or when
+  // we have an externally-supplied layout that also provides overall alignment.
+  if (IsMac68kAlign || (ExternalLayout && !InferAlignment))
+    return;
+
+  if (NewAlignment > Alignment) {
+    assert(llvm::isPowerOf2_32(NewAlignment.getQuantity() && 
+           "Alignment not a power of 2"));
+    Alignment = NewAlignment;
+  }
+
+  if (UnpackedNewAlignment > UnpackedAlignment) {
+    assert(llvm::isPowerOf2_32(UnpackedNewAlignment.getQuantity() &&
+           "Alignment not a power of 2"));
+    UnpackedAlignment = UnpackedNewAlignment;
+  }
+}
+
+uint64_t
+RecordLayoutBuilder::updateExternalFieldOffset(const FieldDecl *Field, 
+                                               uint64_t ComputedOffset) {
+  assert(ExternalFieldOffsets.find(Field) != ExternalFieldOffsets.end() &&
+         "Field does not have an external offset");
+  
+  uint64_t ExternalFieldOffset = ExternalFieldOffsets[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::fromQuantity(1);
+    InferAlignment = false;
+  }
+  
+  // Use the externally-supplied field offset.
+  return ExternalFieldOffset;
+}
+
+void RecordLayoutBuilder::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)
+          << (D->getParent()->isStruct() ? 0 : 1) // struct|class
+          << Context.getTypeDeclType(D->getParent())
+          << PadSize
+          << (InBits ? 1 : 0) /*(byte|bit)*/ << (PadSize > 1) // plural or not
+          << D->getIdentifier();
+    else
+      Diag(D->getLocation(), diag::warn_padded_struct_anon_field)
+          << (D->getParent()->isStruct() ? 0 : 1) // struct|class
+          << Context.getTypeDeclType(D->getParent())
+          << PadSize
+          << (InBits ? 1 : 0) /*(byte|bit)*/ << (PadSize > 1); // plural or not
+  }
+
+  // Warn if we packed it unnecessarily. If the alignment is 1 byte don't
+  // bother since there won't be alignment issues.
+  if (isPacked && UnpackedAlign > CharBitNum && Offset == UnpackedOffset)
+    Diag(D->getLocation(), diag::warn_unnecessary_packed)
+        << D->getIdentifier();
+}
+
+const CXXMethodDecl *
+RecordLayoutBuilder::ComputeKeyFunction(const CXXRecordDecl *RD) {
+  // If a class isn't polymorphic it doesn't have a key function.
+  if (!RD->isPolymorphic())
+    return 0;
+
+  // 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->getLinkage() != ExternalLinkage)
+    return 0;
+
+  // Template instantiations don't have key functions,see Itanium C++ ABI 5.2.6.
+  // Same behavior as GCC.
+  TemplateSpecializationKind TSK = RD->getTemplateSpecializationKind();
+  if (TSK == TSK_ImplicitInstantiation ||
+      TSK == TSK_ExplicitInstantiationDefinition)
+    return 0;
+
+  for (CXXRecordDecl::method_iterator I = RD->method_begin(),
+         E = RD->method_end(); I != E; ++I) {
+    const CXXMethodDecl *MD = *I;
+
+    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())
+      continue;
+
+    if (MD->hasInlineBody())
+      continue;
+
+    // We found it.
+    return MD;
+  }
+
+  return 0;
+}
+
+DiagnosticBuilder
+RecordLayoutBuilder::Diag(SourceLocation Loc, unsigned DiagID) {
+  return Context.getDiagnostics().Report(Loc, DiagID);
+}
+
+/// getASTRecordLayout - Get or compute information about the layout of the
+/// specified record (struct/union/class), which indicates its size and field
+/// position information.
+const ASTRecordLayout &
+ASTContext::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())
+    getExternalSource()->CompleteType(const_cast<RecordDecl*>(D));
+    
+  D = D->getDefinition();
+  assert(D && "Cannot get layout of forward declarations!");
+  assert(D->isCompleteDefinition() && "Cannot layout type before complete!");
+
+  // 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;
+
+  const ASTRecordLayout *NewEntry;
+
+  if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D)) {
+    EmptySubobjectMap EmptySubobjects(*this, RD);
+    RecordLayoutBuilder Builder(*this, &EmptySubobjects);
+    Builder.Layout(RD);
+
+    // MSVC gives the vb-table pointer an alignment equal to that of
+    // the non-virtual part of the structure.  That's an inherently
+    // multi-pass operation.  If our first pass doesn't give us
+    // adequate alignment, try again with the specified minimum
+    // alignment.  This is *much* more maintainable than computing the
+    // alignment in advance in a separately-coded pass; it's also
+    // significantly more efficient in the common case where the
+    // vb-table doesn't need extra padding.
+    if (Builder.VBPtrOffset != CharUnits::fromQuantity(-1) &&
+        (Builder.VBPtrOffset % Builder.NonVirtualAlignment) != 0) {
+      Builder.resetWithTargetAlignment(Builder.NonVirtualAlignment);
+      Builder.Layout(RD);
+    }
+
+    // FIXME: This is not always correct. See the part about bitfields at
+    // http://www.codesourcery.com/public/cxx-abi/abi.html#POD for more info.
+    // FIXME: IsPODForThePurposeOfLayout should be stored in the record layout.
+    // This does not affect the calculations of MSVC layouts
+    bool IsPODForThePurposeOfLayout = 
+      (!Builder.isMicrosoftCXXABI() && cast<CXXRecordDecl>(D)->isPOD());
+
+    // FIXME: This should be done in FinalizeLayout.
+    CharUnits DataSize =
+      IsPODForThePurposeOfLayout ? Builder.getSize() : Builder.getDataSize();
+    CharUnits NonVirtualSize = 
+      IsPODForThePurposeOfLayout ? DataSize : Builder.NonVirtualSize;
+
+    NewEntry =
+      new (*this) ASTRecordLayout(*this, Builder.getSize(), 
+                                  Builder.Alignment,
+                                  Builder.VFPtrOffset,
+                                  Builder.VBPtrOffset,
+                                  DataSize, 
+                                  Builder.FieldOffsets.data(),
+                                  Builder.FieldOffsets.size(),
+                                  NonVirtualSize,
+                                  Builder.NonVirtualAlignment,
+                                  EmptySubobjects.SizeOfLargestEmptySubobject,
+                                  Builder.PrimaryBase,
+                                  Builder.PrimaryBaseIsVirtual,
+                                  Builder.Bases, Builder.VBases);
+  } else {
+    RecordLayoutBuilder Builder(*this, /*EmptySubobjects=*/0);
+    Builder.Layout(D);
+
+    NewEntry =
+      new (*this) ASTRecordLayout(*this, Builder.getSize(), 
+                                  Builder.Alignment,
+                                  Builder.getSize(),
+                                  Builder.FieldOffsets.data(),
+                                  Builder.FieldOffsets.size());
+  }
+
+  ASTRecordLayouts[D] = NewEntry;
+
+  if (getLangOpts().DumpRecordLayouts) {
+    llvm::errs() << "\n*** Dumping AST Record Layout\n";
+    DumpRecordLayout(D, llvm::errs(), getLangOpts().DumpRecordLayoutsSimple);
+  }
+
+  return *NewEntry;
+}
+
+const CXXMethodDecl *ASTContext::getKeyFunction(const CXXRecordDecl *RD) {
+  RD = cast<CXXRecordDecl>(RD->getDefinition());
+  assert(RD && "Cannot get key function for forward declarations!");
+
+  const CXXMethodDecl *&Entry = KeyFunctions[RD];
+  if (!Entry)
+    Entry = RecordLayoutBuilder::ComputeKeyFunction(RD);
+
+  return Entry;
+}
+
+static uint64_t getFieldOffset(const ASTContext &C, const FieldDecl *FD) {
+  const ASTRecordLayout &Layout = C.getASTRecordLayout(FD->getParent());
+  return Layout.getFieldOffset(FD->getFieldIndex());
+}
+
+uint64_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 (IndirectFieldDecl::chain_iterator CI = IFD->chain_begin(),
+                                           CE = IFD->chain_end();
+         CI != CE; ++CI)
+      OffsetInBits += ::getFieldOffset(*this, cast<FieldDecl>(*CI));
+  }
+
+  return OffsetInBits;
+}
+
+/// getObjCLayout - Get or compute information about the layout of the
+/// given interface.
+///
+/// \param Impl - If given, also include the layout of the interface's
+/// implementation. This may differ by including synthesized ivars.
+const ASTRecordLayout &
+ASTContext::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->isThisDeclarationADefinition() && "Invalid interface decl!");
+
+  // Look up this layout, if already laid out, return what we have.
+  ObjCContainerDecl *Key =
+    Impl ? (ObjCContainerDecl*) Impl : (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 sythesized 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, 0);
+  }
+
+  RecordLayoutBuilder Builder(*this, /*EmptySubobjects=*/0);
+  Builder.Layout(D);
+
+  const ASTRecordLayout *NewEntry =
+    new (*this) ASTRecordLayout(*this, Builder.getSize(), 
+                                Builder.Alignment,
+                                Builder.getDataSize(),
+                                Builder.FieldOffsets.data(),
+                                Builder.FieldOffsets.size());
+
+  ObjCLayouts[Key] = NewEntry;
+
+  return *NewEntry;
+}
+
+static void PrintOffset(raw_ostream &OS,
+                        CharUnits Offset, unsigned IndentLevel) {
+  OS << llvm::format("%4" PRId64 " | ", (int64_t)Offset.getQuantity());
+  OS.indent(IndentLevel * 2);
+}
+
+static void DumpCXXRecordLayout(raw_ostream &OS,
+                                const CXXRecordDecl *RD, const ASTContext &C,
+                                CharUnits Offset,
+                                unsigned IndentLevel,
+                                const char* Description,
+                                bool IncludeVirtualBases) {
+  const ASTRecordLayout &Layout = C.getASTRecordLayout(RD);
+
+  PrintOffset(OS, Offset, IndentLevel);
+  OS << C.getTypeDeclType(const_cast<CXXRecordDecl *>(RD)).getAsString();
+  if (Description)
+    OS << ' ' << Description;
+  if (RD->isEmpty())
+    OS << " (empty)";
+  OS << '\n';
+
+  IndentLevel++;
+
+  const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase();
+  bool HasVfptr = Layout.getVFPtrOffset() != CharUnits::fromQuantity(-1);
+  bool HasVbptr = Layout.getVBPtrOffset() != CharUnits::fromQuantity(-1);
+
+  // Vtable pointer.
+  if (RD->isDynamicClass() && !PrimaryBase &&
+      C.getTargetInfo().getCXXABI() != CXXABI_Microsoft) {
+    PrintOffset(OS, Offset, IndentLevel);
+    OS << '(' << *RD << " vtable pointer)\n";
+  }
+  
+  // Dump (non-virtual) bases
+  for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
+         E = RD->bases_end(); I != E; ++I) {
+    assert(!I->getType()->isDependentType() &&
+           "Cannot layout class with dependent bases.");
+    if (I->isVirtual())
+      continue;
+
+    const CXXRecordDecl *Base =
+      cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
+
+    CharUnits BaseOffset = Offset + Layout.getBaseClassOffset(Base);
+
+    DumpCXXRecordLayout(OS, Base, C, BaseOffset, IndentLevel,
+                        Base == PrimaryBase ? "(primary base)" : "(base)",
+                        /*IncludeVirtualBases=*/false);
+  }
+
+  // vfptr and vbptr (for Microsoft C++ ABI)
+  if (HasVfptr) {
+    PrintOffset(OS, Offset + Layout.getVFPtrOffset(), IndentLevel);
+    OS << '(' << *RD << " vftable pointer)\n";
+  }
+  if (HasVbptr) {
+    PrintOffset(OS, Offset + Layout.getVBPtrOffset(), IndentLevel);
+    OS << '(' << *RD << " vbtable pointer)\n";
+  }
+
+  // Dump fields.
+  uint64_t FieldNo = 0;
+  for (CXXRecordDecl::field_iterator I = RD->field_begin(),
+         E = RD->field_end(); I != E; ++I, ++FieldNo) {
+    const FieldDecl *Field = *I;
+    CharUnits FieldOffset = Offset + 
+      C.toCharUnitsFromBits(Layout.getFieldOffset(FieldNo));
+
+    if (const RecordType *RT = Field->getType()->getAs<RecordType>()) {
+      if (const CXXRecordDecl *D = dyn_cast<CXXRecordDecl>(RT->getDecl())) {
+        DumpCXXRecordLayout(OS, D, C, FieldOffset, IndentLevel,
+                            Field->getName().data(),
+                            /*IncludeVirtualBases=*/true);
+        continue;
+      }
+    }
+
+    PrintOffset(OS, FieldOffset, IndentLevel);
+    OS << Field->getType().getAsString() << ' ' << *Field << '\n';
+  }
+
+  if (!IncludeVirtualBases)
+    return;
+
+  // Dump virtual bases.
+  for (CXXRecordDecl::base_class_const_iterator I = RD->vbases_begin(),
+         E = RD->vbases_end(); I != E; ++I) {
+    assert(I->isVirtual() && "Found non-virtual class!");
+    const CXXRecordDecl *VBase =
+      cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl());
+
+    CharUnits VBaseOffset = Offset + Layout.getVBaseClassOffset(VBase);
+    DumpCXXRecordLayout(OS, VBase, C, VBaseOffset, IndentLevel,
+                        VBase == PrimaryBase ?
+                        "(primary virtual base)" : "(virtual base)",
+                        /*IncludeVirtualBases=*/false);
+  }
+
+  OS << "  sizeof=" << Layout.getSize().getQuantity();
+  OS << ", dsize=" << Layout.getDataSize().getQuantity();
+  OS << ", align=" << Layout.getAlignment().getQuantity() << '\n';
+  OS << "  nvsize=" << Layout.getNonVirtualSize().getQuantity();
+  OS << ", nvalign=" << Layout.getNonVirtualAlign().getQuantity() << '\n';
+  OS << '\n';
+}
+
+void ASTContext::DumpRecordLayout(const RecordDecl *RD,
+                                  raw_ostream &OS,
+                                  bool Simple) const {
+  const ASTRecordLayout &Info = getASTRecordLayout(RD);
+
+  if (const CXXRecordDecl *CXXRD = dyn_cast<CXXRecordDecl>(RD))
+    if (!Simple)
+      return DumpCXXRecordLayout(OS, CXXRD, *this, CharUnits(), 0, 0,
+                                 /*IncludeVirtualBases=*/true);
+
+  OS << "Type: " << getTypeDeclType(RD).getAsString() << "\n";
+  if (!Simple) {
+    OS << "Record: ";
+    RD->dump();
+  }
+  OS << "\nLayout: ";
+  OS << "<ASTRecordLayout\n";
+  OS << "  Size:" << toBits(Info.getSize()) << "\n";
+  OS << "  DataSize:" << toBits(Info.getDataSize()) << "\n";
+  OS << "  Alignment:" << toBits(Info.getAlignment()) << "\n";
+  OS << "  FieldOffsets: [";
+  for (unsigned i = 0, e = Info.getFieldCount(); i != e; ++i) {
+    if (i) OS << ", ";
+    OS << Info.getFieldOffset(i);
+  }
+  OS << "]>\n";
+}