clang/lib/CodeGen/CGRecordLayoutBuilder.cpp - toolchain/llvm-project - Gitiles

 //===--- CGRecordLayoutBuilder.cpp - Record builder helper ------*- C++ -*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This is a helper class used to build CGRecordLayout objects and LLVM types.
 //
 //===----------------------------------------------------------------------===//

 #include "CGRecordLayoutBuilder.h"

 #include "clang/AST/ASTContext.h"
 #include "clang/AST/Attr.h"
 #include "clang/AST/DeclCXX.h"
 #include "clang/AST/Expr.h"
 #include "clang/AST/RecordLayout.h"
 #include "CodeGenTypes.h"
 #include "llvm/DerivedTypes.h"
 #include "llvm/Target/TargetData.h"


 using namespace clang;
 using namespace CodeGen;

 void CGRecordLayoutBuilder::Layout(const RecordDecl *D) {
   Alignment = Types.getContext().getASTRecordLayout(D).getAlignment() / 8;
   Packed = D->hasAttr<PackedAttr>();

   if (D->isUnion()) {
     LayoutUnion(D);
     return;
   }

   if (LayoutFields(D))
     return;

   // We weren't able to layout the struct. Try again with a packed struct
   Packed = true;
   AlignmentAsLLVMStruct = 1;
   NextFieldOffsetInBytes = 0;
   FieldTypes.clear();
   LLVMFields.clear();
   LLVMBitFields.clear();

   LayoutFields(D);
 }

 void CGRecordLayoutBuilder::LayoutBitField(const FieldDecl *D,
                                            uint64_t FieldOffset) {
   uint64_t FieldSize =
     D->getBitWidth()->EvaluateAsInt(Types.getContext()).getZExtValue();

   if (FieldSize == 0)
     return;

   uint64_t NextFieldOffset = NextFieldOffsetInBytes * 8;
   unsigned NumBytesToAppend;

   if (FieldOffset < NextFieldOffset) {
     assert(BitsAvailableInLastField && "Bitfield size mismatch!");
     assert(NextFieldOffsetInBytes && "Must have laid out at least one byte!");

     // The bitfield begins in the previous bit-field.
     NumBytesToAppend =
       llvm::RoundUpToAlignment(FieldSize - BitsAvailableInLastField, 8) / 8;
   } else {
     assert(FieldOffset % 8 == 0 && "Field offset not aligned correctly");

     // Append padding if necessary.
     AppendBytes((FieldOffset - NextFieldOffset) / 8);

     NumBytesToAppend =
       llvm::RoundUpToAlignment(FieldSize, 8) / 8;

     assert(NumBytesToAppend && "No bytes to append!");
   }

   const llvm::Type *Ty = Types.ConvertTypeForMemRecursive(D->getType());
   uint64_t TypeSizeInBits = getTypeSizeInBytes(Ty) * 8;

   LLVMBitFields.push_back(LLVMBitFieldInfo(D, FieldOffset / TypeSizeInBits,
                                            FieldOffset % TypeSizeInBits,
                                            FieldSize));

   AppendBytes(NumBytesToAppend);

   AlignmentAsLLVMStruct = std::max(AlignmentAsLLVMStruct, getTypeAlignment(Ty));

   BitsAvailableInLastField =
     NextFieldOffsetInBytes * 8 - (FieldOffset + FieldSize);
 }

 bool CGRecordLayoutBuilder::LayoutField(const FieldDecl *D,
                                         uint64_t FieldOffset) {
   // If the field is packed, then we need a packed struct.
   if (!Packed && D->hasAttr<PackedAttr>())
     return false;

   if (D->isBitField()) {
     // We must use packed structs for unnamed bit fields since they
     // don't affect the struct alignment.
     if (!Packed && !D->getDeclName())
       return false;

     LayoutBitField(D, FieldOffset);
     return true;
   }

   assert(FieldOffset % 8 == 0 && "FieldOffset is not on a byte boundary!");
   uint64_t FieldOffsetInBytes = FieldOffset / 8;

   const llvm::Type *Ty = Types.ConvertTypeForMemRecursive(D->getType());
   unsigned TypeAlignment = getTypeAlignment(Ty);

   // If the type alignment is larger then the struct alignment, we must use
   // a packed struct.
   if (TypeAlignment > Alignment) {
     assert(!Packed && "Alignment is wrong even with packed struct!");
     return false;
   }

   if (const RecordType *RT = D->getType()->getAs<RecordType>()) {
     const RecordDecl *RD = cast<RecordDecl>(RT->getDecl());
     if (const PragmaPackAttr *PPA = RD->getAttr<PragmaPackAttr>()) {
       if (PPA->getAlignment() != TypeAlignment * 8 && !Packed)
         return false;
     }
   }

   // Round up the field offset to the alignment of the field type.
   uint64_t AlignedNextFieldOffsetInBytes =
     llvm::RoundUpToAlignment(NextFieldOffsetInBytes, TypeAlignment);

   if (FieldOffsetInBytes < AlignedNextFieldOffsetInBytes) {
     assert(!Packed && "Could not place field even with packed struct!");
     return false;
   }

   if (AlignedNextFieldOffsetInBytes < FieldOffsetInBytes) {
     // Even with alignment, the field offset is not at the right place,
     // insert padding.
     uint64_t PaddingInBytes = FieldOffsetInBytes - NextFieldOffsetInBytes;

     AppendBytes(PaddingInBytes);
   }

   // Now append the field.
   LLVMFields.push_back(LLVMFieldInfo(D, FieldTypes.size()));
   AppendField(FieldOffsetInBytes, Ty);

   return true;
 }

 void CGRecordLayoutBuilder::LayoutUnion(const RecordDecl *D) {
   assert(D->isUnion() && "Can't call LayoutUnion on a non-union record!");

   const ASTRecordLayout &Layout = Types.getContext().getASTRecordLayout(D);

   const llvm::Type *Ty = 0;
   uint64_t Size = 0;
   unsigned Align = 0;

   unsigned FieldNo = 0;
   for (RecordDecl::field_iterator Field = D->field_begin(),
        FieldEnd = D->field_end(); Field != FieldEnd; ++Field, ++FieldNo) {
     assert(Layout.getFieldOffset(FieldNo) == 0 &&
           "Union field offset did not start at the beginning of record!");

     if (Field->isBitField()) {
       uint64_t FieldSize =
         Field->getBitWidth()->EvaluateAsInt(Types.getContext()).getZExtValue();

       // Ignore zero sized bit fields.
       if (FieldSize == 0)
         continue;

       // Add the bit field info.
       Types.addBitFieldInfo(*Field, 0, 0, FieldSize);
     } else
       Types.addFieldInfo(*Field, 0);

     const llvm::Type *FieldTy =
       Types.ConvertTypeForMemRecursive(Field->getType());
     unsigned FieldAlign = Types.getTargetData().getABITypeAlignment(FieldTy);
     uint64_t FieldSize = Types.getTargetData().getTypeAllocSize(FieldTy);

     if (FieldAlign < Align)
       continue;

     if (FieldAlign > Align || FieldSize > Size) {
       Ty = FieldTy;
       Align = FieldAlign;
       Size = FieldSize;
     }
   }

   // Now add our field.
   if (Ty) {
     AppendField(0, Ty);

     if (getTypeAlignment(Ty) > Layout.getAlignment() / 8) {
       // We need a packed struct.
       Packed = true;
       Align = 1;
     }
   }
   if (!Align) {
     assert((D->field_begin() == D->field_end()) && "LayoutUnion - Align 0");
     Align = 1;
   }

   // Append tail padding.
   if (Layout.getSize() / 8 > Size)
     AppendPadding(Layout.getSize() / 8, Align);
 }

 bool CGRecordLayoutBuilder::LayoutFields(const RecordDecl *D) {
   assert(!D->isUnion() && "Can't call LayoutFields on a union!");
   assert(Alignment && "Did not set alignment!");

   const ASTRecordLayout &Layout = Types.getContext().getASTRecordLayout(D);

   unsigned FieldNo = 0;

   for (RecordDecl::field_iterator Field = D->field_begin(),
        FieldEnd = D->field_end(); Field != FieldEnd; ++Field, ++FieldNo) {
     if (!LayoutField(*Field, Layout.getFieldOffset(FieldNo))) {
       assert(!Packed &&
              "Could not layout fields even with a packed LLVM struct!");
       return false;
     }
   }

   // Append tail padding if necessary.
   AppendTailPadding(Layout.getSize());

   return true;
 }

 void CGRecordLayoutBuilder::AppendTailPadding(uint64_t RecordSize) {
   assert(RecordSize % 8 == 0 && "Invalid record size!");

   uint64_t RecordSizeInBytes = RecordSize / 8;
   assert(NextFieldOffsetInBytes <= RecordSizeInBytes && "Size mismatch!");

   unsigned NumPadBytes = RecordSizeInBytes - NextFieldOffsetInBytes;
   AppendBytes(NumPadBytes);
 }

 void CGRecordLayoutBuilder::AppendField(uint64_t FieldOffsetInBytes,
                                         const llvm::Type *FieldTy) {
   AlignmentAsLLVMStruct = std::max(AlignmentAsLLVMStruct,
                                    getTypeAlignment(FieldTy));

   uint64_t FieldSizeInBytes = getTypeSizeInBytes(FieldTy);

   FieldTypes.push_back(FieldTy);

   NextFieldOffsetInBytes = FieldOffsetInBytes + FieldSizeInBytes;
   BitsAvailableInLastField = 0;
 }

 void
 CGRecordLayoutBuilder::AppendPadding(uint64_t FieldOffsetInBytes,
                                      const llvm::Type *FieldTy) {
   AppendPadding(FieldOffsetInBytes, getTypeAlignment(FieldTy));
 }

 void CGRecordLayoutBuilder::AppendPadding(uint64_t FieldOffsetInBytes,
                                           unsigned FieldAlignment) {
   assert(NextFieldOffsetInBytes <= FieldOffsetInBytes &&
          "Incorrect field layout!");

   // Round up the field offset to the alignment of the field type.
   uint64_t AlignedNextFieldOffsetInBytes =
     llvm::RoundUpToAlignment(NextFieldOffsetInBytes, FieldAlignment);

   if (AlignedNextFieldOffsetInBytes < FieldOffsetInBytes) {
     // Even with alignment, the field offset is not at the right place,
     // insert padding.
     uint64_t PaddingInBytes = FieldOffsetInBytes - NextFieldOffsetInBytes;

     AppendBytes(PaddingInBytes);
   }
 }

 void CGRecordLayoutBuilder::AppendBytes(uint64_t NumBytes) {
   if (NumBytes == 0)
     return;

   const llvm::Type *Ty = llvm::Type::getInt8Ty(Types.getLLVMContext());
   if (NumBytes > 1)
     Ty = llvm::ArrayType::get(Ty, NumBytes);

   // Append the padding field
   AppendField(NextFieldOffsetInBytes, Ty);
 }

 unsigned CGRecordLayoutBuilder::getTypeAlignment(const llvm::Type *Ty) const {
   if (Packed)
     return 1;

   return Types.getTargetData().getABITypeAlignment(Ty);
 }

 uint64_t CGRecordLayoutBuilder::getTypeSizeInBytes(const llvm::Type *Ty) const {
   return Types.getTargetData().getTypeAllocSize(Ty);
 }

 void CGRecordLayoutBuilder::CheckForMemberPointer(const FieldDecl *FD) {
   // This record already contains a member pointer.
   if (ContainsMemberPointer)
     return;

   // Can only have member pointers if we're compiling C++.
   if (!Types.getContext().getLangOptions().CPlusPlus)
     return;

   QualType Ty = FD->getType();

   if (Ty->isMemberPointerType()) {
     // We have a member pointer!
     ContainsMemberPointer = true;
     return;
   }

 }

 static const CXXMethodDecl *GetKeyFunction(const RecordDecl *D) {
   const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D);
   if (!RD || !RD->isDynamicClass())
     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;

     const FunctionDecl *fn;
     if (MD->getBody(fn) && !fn->isOutOfLine())
       continue;

     // We found it.
     return MD;
   }

   return 0;
 }

 CGRecordLayout *
 CGRecordLayoutBuilder::ComputeLayout(CodeGenTypes &Types,
                                      const RecordDecl *D) {
   CGRecordLayoutBuilder Builder(Types);

   Builder.Layout(D);

   const llvm::Type *Ty = llvm::StructType::get(Types.getLLVMContext(),
                                                Builder.FieldTypes,
                                                Builder.Packed);
   assert(Types.getContext().getASTRecordLayout(D).getSize() / 8 ==
          Types.getTargetData().getTypeAllocSize(Ty) &&
          "Type size mismatch!");

   // Add all the field numbers.
   for (unsigned i = 0, e = Builder.LLVMFields.size(); i != e; ++i) {
     const FieldDecl *FD = Builder.LLVMFields[i].first;
     unsigned FieldNo = Builder.LLVMFields[i].second;

     Types.addFieldInfo(FD, FieldNo);
   }

   // Add bitfield info.
   for (unsigned i = 0, e = Builder.LLVMBitFields.size(); i != e; ++i) {
     const LLVMBitFieldInfo &Info = Builder.LLVMBitFields[i];

     Types.addBitFieldInfo(Info.FD, Info.FieldNo, Info.Start, Info.Size);
   }

   const CXXMethodDecl *KeyFunction = GetKeyFunction(D);

   return new CGRecordLayout(Ty, Builder.ContainsMemberPointer, KeyFunction);
 }
	//===--- CGRecordLayoutBuilder.cpp - Record builder helper ------- C++ --===//
	//
	// The LLVM Compiler Infrastructure
	//
	// This file is distributed under the University of Illinois Open Source
	// License. See LICENSE.TXT for details.
	//
	//===----------------------------------------------------------------------===//
	//
	// This is a helper class used to build CGRecordLayout objects and LLVM types.
	//
	//===----------------------------------------------------------------------===//

	#include "CGRecordLayoutBuilder.h"

	#include "clang/AST/ASTContext.h"
	#include "clang/AST/Attr.h"
	#include "clang/AST/DeclCXX.h"
	#include "clang/AST/Expr.h"
	#include "clang/AST/RecordLayout.h"
	#include "CodeGenTypes.h"
	#include "llvm/DerivedTypes.h"
	#include "llvm/Target/TargetData.h"


	using namespace clang;
	using namespace CodeGen;

	void CGRecordLayoutBuilder::Layout(const RecordDecl *D) {
	Alignment = Types.getContext().getASTRecordLayout(D).getAlignment() / 8;
	Packed = D->hasAttr<PackedAttr>();

	if (D->isUnion()) {
	LayoutUnion(D);
	return;
	}

	if (LayoutFields(D))
	return;

	// We weren't able to layout the struct. Try again with a packed struct
	Packed = true;
	AlignmentAsLLVMStruct = 1;
	NextFieldOffsetInBytes = 0;
	FieldTypes.clear();
	LLVMFields.clear();
	LLVMBitFields.clear();

	LayoutFields(D);
	}

	void CGRecordLayoutBuilder::LayoutBitField(const FieldDecl *D,
	uint64_t FieldOffset) {
	uint64_t FieldSize =
	D->getBitWidth()->EvaluateAsInt(Types.getContext()).getZExtValue();

	if (FieldSize == 0)
	return;

	uint64_t NextFieldOffset = NextFieldOffsetInBytes * 8;
	unsigned NumBytesToAppend;

	if (FieldOffset < NextFieldOffset) {
	assert(BitsAvailableInLastField && "Bitfield size mismatch!");
	assert(NextFieldOffsetInBytes && "Must have laid out at least one byte!");

	// The bitfield begins in the previous bit-field.
	NumBytesToAppend =
	llvm::RoundUpToAlignment(FieldSize - BitsAvailableInLastField, 8) / 8;
	} else {
	assert(FieldOffset % 8 == 0 && "Field offset not aligned correctly");

	// Append padding if necessary.
	AppendBytes((FieldOffset - NextFieldOffset) / 8);

	NumBytesToAppend =
	llvm::RoundUpToAlignment(FieldSize, 8) / 8;

	assert(NumBytesToAppend && "No bytes to append!");
	}

	const llvm::Type *Ty = Types.ConvertTypeForMemRecursive(D->getType());
	uint64_t TypeSizeInBits = getTypeSizeInBytes(Ty) * 8;

	LLVMBitFields.push_back(LLVMBitFieldInfo(D, FieldOffset / TypeSizeInBits,
	FieldOffset % TypeSizeInBits,
	FieldSize));

	AppendBytes(NumBytesToAppend);

	AlignmentAsLLVMStruct = std::max(AlignmentAsLLVMStruct, getTypeAlignment(Ty));

	BitsAvailableInLastField =
	NextFieldOffsetInBytes * 8 - (FieldOffset + FieldSize);
	}

	bool CGRecordLayoutBuilder::LayoutField(const FieldDecl *D,
	uint64_t FieldOffset) {
	// If the field is packed, then we need a packed struct.
	if (!Packed && D->hasAttr<PackedAttr>())
	return false;

	if (D->isBitField()) {
	// We must use packed structs for unnamed bit fields since they
	// don't affect the struct alignment.
	if (!Packed && !D->getDeclName())
	return false;

	LayoutBitField(D, FieldOffset);
	return true;
	}

	assert(FieldOffset % 8 == 0 && "FieldOffset is not on a byte boundary!");
	uint64_t FieldOffsetInBytes = FieldOffset / 8;

	const llvm::Type *Ty = Types.ConvertTypeForMemRecursive(D->getType());
	unsigned TypeAlignment = getTypeAlignment(Ty);

	// If the type alignment is larger then the struct alignment, we must use
	// a packed struct.
	if (TypeAlignment > Alignment) {
	assert(!Packed && "Alignment is wrong even with packed struct!");
	return false;
	}

	if (const RecordType *RT = D->getType()->getAs<RecordType>()) {
	const RecordDecl *RD = cast<RecordDecl>(RT->getDecl());
	if (const PragmaPackAttr *PPA = RD->getAttr<PragmaPackAttr>()) {
	if (PPA->getAlignment() != TypeAlignment * 8 && !Packed)
	return false;
	}
	}

	// Round up the field offset to the alignment of the field type.
	uint64_t AlignedNextFieldOffsetInBytes =
	llvm::RoundUpToAlignment(NextFieldOffsetInBytes, TypeAlignment);

	if (FieldOffsetInBytes < AlignedNextFieldOffsetInBytes) {
	assert(!Packed && "Could not place field even with packed struct!");
	return false;
	}

	if (AlignedNextFieldOffsetInBytes < FieldOffsetInBytes) {
	// Even with alignment, the field offset is not at the right place,
	// insert padding.
	uint64_t PaddingInBytes = FieldOffsetInBytes - NextFieldOffsetInBytes;

	AppendBytes(PaddingInBytes);
	}

	// Now append the field.
	LLVMFields.push_back(LLVMFieldInfo(D, FieldTypes.size()));
	AppendField(FieldOffsetInBytes, Ty);

	return true;
	}

	void CGRecordLayoutBuilder::LayoutUnion(const RecordDecl *D) {
	assert(D->isUnion() && "Can't call LayoutUnion on a non-union record!");

	const ASTRecordLayout &Layout = Types.getContext().getASTRecordLayout(D);

	const llvm::Type *Ty = 0;
	uint64_t Size = 0;
	unsigned Align = 0;

	unsigned FieldNo = 0;
	for (RecordDecl::field_iterator Field = D->field_begin(),
	FieldEnd = D->field_end(); Field != FieldEnd; ++Field, ++FieldNo) {
	assert(Layout.getFieldOffset(FieldNo) == 0 &&
	"Union field offset did not start at the beginning of record!");

	if (Field->isBitField()) {
	uint64_t FieldSize =
	Field->getBitWidth()->EvaluateAsInt(Types.getContext()).getZExtValue();

	// Ignore zero sized bit fields.
	if (FieldSize == 0)
	continue;

	// Add the bit field info.
	Types.addBitFieldInfo(*Field, 0, 0, FieldSize);
	} else
	Types.addFieldInfo(*Field, 0);

	const llvm::Type *FieldTy =
	Types.ConvertTypeForMemRecursive(Field->getType());
	unsigned FieldAlign = Types.getTargetData().getABITypeAlignment(FieldTy);
	uint64_t FieldSize = Types.getTargetData().getTypeAllocSize(FieldTy);

	if (FieldAlign < Align)
	continue;

	if (FieldAlign > Align \|\| FieldSize > Size) {
	Ty = FieldTy;
	Align = FieldAlign;
	Size = FieldSize;
	}
	}

	// Now add our field.
	if (Ty) {
	AppendField(0, Ty);

	if (getTypeAlignment(Ty) > Layout.getAlignment() / 8) {
	// We need a packed struct.
	Packed = true;
	Align = 1;
	}
	}
	if (!Align) {
	assert((D->field_begin() == D->field_end()) && "LayoutUnion - Align 0");
	Align = 1;
	}

	// Append tail padding.
	if (Layout.getSize() / 8 > Size)
	AppendPadding(Layout.getSize() / 8, Align);
	}

	bool CGRecordLayoutBuilder::LayoutFields(const RecordDecl *D) {
	assert(!D->isUnion() && "Can't call LayoutFields on a union!");
	assert(Alignment && "Did not set alignment!");

	const ASTRecordLayout &Layout = Types.getContext().getASTRecordLayout(D);

	unsigned FieldNo = 0;

	for (RecordDecl::field_iterator Field = D->field_begin(),
	FieldEnd = D->field_end(); Field != FieldEnd; ++Field, ++FieldNo) {
	if (!LayoutField(*Field, Layout.getFieldOffset(FieldNo))) {
	assert(!Packed &&
	"Could not layout fields even with a packed LLVM struct!");
	return false;
	}
	}

	// Append tail padding if necessary.
	AppendTailPadding(Layout.getSize());

	return true;
	}

	void CGRecordLayoutBuilder::AppendTailPadding(uint64_t RecordSize) {
	assert(RecordSize % 8 == 0 && "Invalid record size!");

	uint64_t RecordSizeInBytes = RecordSize / 8;
	assert(NextFieldOffsetInBytes <= RecordSizeInBytes && "Size mismatch!");

	unsigned NumPadBytes = RecordSizeInBytes - NextFieldOffsetInBytes;
	AppendBytes(NumPadBytes);
	}

	void CGRecordLayoutBuilder::AppendField(uint64_t FieldOffsetInBytes,
	const llvm::Type *FieldTy) {
	AlignmentAsLLVMStruct = std::max(AlignmentAsLLVMStruct,
	getTypeAlignment(FieldTy));

	uint64_t FieldSizeInBytes = getTypeSizeInBytes(FieldTy);

	FieldTypes.push_back(FieldTy);

	NextFieldOffsetInBytes = FieldOffsetInBytes + FieldSizeInBytes;
	BitsAvailableInLastField = 0;
	}

	void
	CGRecordLayoutBuilder::AppendPadding(uint64_t FieldOffsetInBytes,
	const llvm::Type *FieldTy) {
	AppendPadding(FieldOffsetInBytes, getTypeAlignment(FieldTy));
	}

	void CGRecordLayoutBuilder::AppendPadding(uint64_t FieldOffsetInBytes,
	unsigned FieldAlignment) {
	assert(NextFieldOffsetInBytes <= FieldOffsetInBytes &&
	"Incorrect field layout!");

	// Round up the field offset to the alignment of the field type.
	uint64_t AlignedNextFieldOffsetInBytes =
	llvm::RoundUpToAlignment(NextFieldOffsetInBytes, FieldAlignment);

	if (AlignedNextFieldOffsetInBytes < FieldOffsetInBytes) {
	// Even with alignment, the field offset is not at the right place,
	// insert padding.
	uint64_t PaddingInBytes = FieldOffsetInBytes - NextFieldOffsetInBytes;

	AppendBytes(PaddingInBytes);
	}
	}

	void CGRecordLayoutBuilder::AppendBytes(uint64_t NumBytes) {
	if (NumBytes == 0)
	return;

	const llvm::Type *Ty = llvm::Type::getInt8Ty(Types.getLLVMContext());
	if (NumBytes > 1)
	Ty = llvm::ArrayType::get(Ty, NumBytes);

	// Append the padding field
	AppendField(NextFieldOffsetInBytes, Ty);
	}

	unsigned CGRecordLayoutBuilder::getTypeAlignment(const llvm::Type *Ty) const {
	if (Packed)
	return 1;

	return Types.getTargetData().getABITypeAlignment(Ty);
	}

	uint64_t CGRecordLayoutBuilder::getTypeSizeInBytes(const llvm::Type *Ty) const {
	return Types.getTargetData().getTypeAllocSize(Ty);
	}

	void CGRecordLayoutBuilder::CheckForMemberPointer(const FieldDecl *FD) {
	// This record already contains a member pointer.
	if (ContainsMemberPointer)
	return;

	// Can only have member pointers if we're compiling C++.
	if (!Types.getContext().getLangOptions().CPlusPlus)
	return;

	QualType Ty = FD->getType();

	if (Ty->isMemberPointerType()) {
	// We have a member pointer!
	ContainsMemberPointer = true;
	return;
	}

	}

	static const CXXMethodDecl GetKeyFunction(const RecordDecl D) {
	const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D);
	if (!RD \|\| !RD->isDynamicClass())
	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;

	const FunctionDecl *fn;
	if (MD->getBody(fn) && !fn->isOutOfLine())
	continue;

	// We found it.
	return MD;
	}

	return 0;
	}

	CGRecordLayout *
	CGRecordLayoutBuilder::ComputeLayout(CodeGenTypes &Types,
	const RecordDecl *D) {
	CGRecordLayoutBuilder Builder(Types);

	Builder.Layout(D);

	const llvm::Type *Ty = llvm::StructType::get(Types.getLLVMContext(),
	Builder.FieldTypes,
	Builder.Packed);
	assert(Types.getContext().getASTRecordLayout(D).getSize() / 8 ==
	Types.getTargetData().getTypeAllocSize(Ty) &&
	"Type size mismatch!");

	// Add all the field numbers.
	for (unsigned i = 0, e = Builder.LLVMFields.size(); i != e; ++i) {
	const FieldDecl *FD = Builder.LLVMFields[i].first;
	unsigned FieldNo = Builder.LLVMFields[i].second;

	Types.addFieldInfo(FD, FieldNo);
	}

	// Add bitfield info.
	for (unsigned i = 0, e = Builder.LLVMBitFields.size(); i != e; ++i) {
	const LLVMBitFieldInfo &Info = Builder.LLVMBitFields[i];

	Types.addBitFieldInfo(Info.FD, Info.FieldNo, Info.Start, Info.Size);
	}

	const CXXMethodDecl *KeyFunction = GetKeyFunction(D);

	return new CGRecordLayout(Ty, Builder.ContainsMemberPointer, KeyFunction);
	}