lib/CodeGen/CGExprAgg.cpp - platform/external/clang - Gitiles

 //===--- CGExprAgg.cpp - Emit LLVM Code from Aggregate Expressions --------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This contains code to emit Aggregate Expr nodes as LLVM code.
 //
 //===----------------------------------------------------------------------===//

 #include "CodeGenFunction.h"
 #include "CodeGenModule.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/StmtVisitor.h"
 #include "llvm/Constants.h"
 #include "llvm/Function.h"
 #include "llvm/GlobalVariable.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Intrinsics.h"
 using namespace clang;
 using namespace CodeGen;

 //===----------------------------------------------------------------------===//
 //                        Aggregate Expression Emitter
 //===----------------------------------------------------------------------===//

 namespace  {
 class VISIBILITY_HIDDEN AggExprEmitter : public StmtVisitor<AggExprEmitter> {
   CodeGenFunction &CGF;
   llvm::IRBuilder<> &Builder;
   llvm::Value *DestPtr;
   bool VolatileDest;
 public:
   AggExprEmitter(CodeGenFunction &cgf, llvm::Value *destPtr, bool volatileDest)
     : CGF(cgf), Builder(CGF.Builder),
       DestPtr(destPtr), VolatileDest(volatileDest) {
   }

   //===--------------------------------------------------------------------===//
   //                               Utilities
   //===--------------------------------------------------------------------===//

   /// EmitAggLoadOfLValue - Given an expression with aggregate type that
   /// represents a value lvalue, this method emits the address of the lvalue,
   /// then loads the result into DestPtr.
   void EmitAggLoadOfLValue(const Expr *E);

   void EmitAggregateCopy(llvm::Value *DestPtr, llvm::Value *SrcPtr,
                          QualType EltTy);

   void EmitAggregateClear(llvm::Value *DestPtr, QualType Ty);

   void EmitNonConstInit(InitListExpr *E);

   //===--------------------------------------------------------------------===//
   //                            Visitor Methods
   //===--------------------------------------------------------------------===//

   void VisitStmt(Stmt *S) {
     CGF.ErrorUnsupported(S, "aggregate expression");
   }
   void VisitParenExpr(ParenExpr *PE) { Visit(PE->getSubExpr()); }

   // l-values.
   void VisitDeclRefExpr(DeclRefExpr *DRE) { EmitAggLoadOfLValue(DRE); }
   void VisitMemberExpr(MemberExpr *ME) { EmitAggLoadOfLValue(ME); }
   void VisitUnaryDeref(UnaryOperator *E) { EmitAggLoadOfLValue(E); }
   void VisitStringLiteral(StringLiteral *E) { EmitAggLoadOfLValue(E); }
   void VisitCompoundLiteralExpr(CompoundLiteralExpr *E)
       { EmitAggLoadOfLValue(E); }

   void VisitArraySubscriptExpr(ArraySubscriptExpr *E) {
     EmitAggLoadOfLValue(E);
   }

   // Operators.
   //  case Expr::UnaryOperatorClass:
   //  case Expr::CastExprClass:
   void VisitImplicitCastExpr(ImplicitCastExpr *E);
   void VisitCallExpr(const CallExpr *E);
   void VisitStmtExpr(const StmtExpr *E);
   void VisitBinaryOperator(const BinaryOperator *BO);
   void VisitBinAssign(const BinaryOperator *E);
   void VisitOverloadExpr(const OverloadExpr *E);
   void VisitBinComma(const BinaryOperator *E);

   void VisitObjCMessageExpr(ObjCMessageExpr *E);


   void VisitConditionalOperator(const ConditionalOperator *CO);
   void VisitInitListExpr(InitListExpr *E);
   void VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) {
     Visit(DAE->getExpr());
   }
   void VisitVAArgExpr(VAArgExpr *E);

   void EmitInitializationToLValue(Expr *E, LValue Address);
   void EmitNullInitializationToLValue(LValue Address, QualType T);
   //  case Expr::ChooseExprClass:

 };
 }  // end anonymous namespace.

 //===----------------------------------------------------------------------===//
 //                                Utilities
 //===----------------------------------------------------------------------===//

 void AggExprEmitter::EmitAggregateClear(llvm::Value *DestPtr, QualType Ty) {
   assert(!Ty->isAnyComplexType() && "Shouldn't happen for complex");

   // Aggregate assignment turns into llvm.memset.
   const llvm::Type *BP = llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
   if (DestPtr->getType() != BP)
     DestPtr = Builder.CreateBitCast(DestPtr, BP, "tmp");

   // Get size and alignment info for this aggregate.
   std::pair<uint64_t, unsigned> TypeInfo = CGF.getContext().getTypeInfo(Ty);

   // FIXME: Handle variable sized types.
   const llvm::Type *IntPtr = llvm::IntegerType::get(CGF.LLVMPointerWidth);

   llvm::Value *MemSetOps[4] = {
     DestPtr,
     llvm::ConstantInt::getNullValue(llvm::Type::Int8Ty),
     // TypeInfo.first describes size in bits.
     llvm::ConstantInt::get(IntPtr, TypeInfo.first/8),
     llvm::ConstantInt::get(llvm::Type::Int32Ty, TypeInfo.second/8)
   };

   Builder.CreateCall(CGF.CGM.getMemSetFn(), MemSetOps, MemSetOps+4);
 }

 void AggExprEmitter::EmitAggregateCopy(llvm::Value *DestPtr,
                                        llvm::Value *SrcPtr, QualType Ty) {
   assert(!Ty->isAnyComplexType() && "Shouldn't happen for complex");

   // Aggregate assignment turns into llvm.memmove.
   const llvm::Type *BP = llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
   if (DestPtr->getType() != BP)
     DestPtr = Builder.CreateBitCast(DestPtr, BP, "tmp");
   if (SrcPtr->getType() != BP)
     SrcPtr = Builder.CreateBitCast(SrcPtr, BP, "tmp");

   // Get size and alignment info for this aggregate.
   std::pair<uint64_t, unsigned> TypeInfo = CGF.getContext().getTypeInfo(Ty);

   // FIXME: Handle variable sized types.
   const llvm::Type *IntPtr = llvm::IntegerType::get(CGF.LLVMPointerWidth);

   llvm::Value *MemMoveOps[4] = {
     DestPtr, SrcPtr,
     // TypeInfo.first describes size in bits.
     llvm::ConstantInt::get(IntPtr, TypeInfo.first/8),
     llvm::ConstantInt::get(llvm::Type::Int32Ty, TypeInfo.second/8)
   };

   Builder.CreateCall(CGF.CGM.getMemMoveFn(), MemMoveOps, MemMoveOps+4);
 }


 /// EmitAggLoadOfLValue - Given an expression with aggregate type that
 /// represents a value lvalue, this method emits the address of the lvalue,
 /// then loads the result into DestPtr.
 void AggExprEmitter::EmitAggLoadOfLValue(const Expr *E) {
   LValue LV = CGF.EmitLValue(E);
   assert(LV.isSimple() && "Can't have aggregate bitfield, vector, etc");
   llvm::Value *SrcPtr = LV.getAddress();

   // If the result is ignored, don't copy from the value.
   if (DestPtr == 0)
     // FIXME: If the source is volatile, we must read from it.
     return;

   EmitAggregateCopy(DestPtr, SrcPtr, E->getType());
 }

 //===----------------------------------------------------------------------===//
 //                            Visitor Methods
 //===----------------------------------------------------------------------===//

 void AggExprEmitter::VisitImplicitCastExpr(ImplicitCastExpr *E) {
   assert(CGF.getContext().typesAreCompatible(
                           E->getSubExpr()->getType().getUnqualifiedType(),
                           E->getType().getUnqualifiedType()) &&
          "Implicit cast types must be compatible");
   Visit(E->getSubExpr());
 }

 void AggExprEmitter::VisitCallExpr(const CallExpr *E) {
   RValue RV = CGF.EmitCallExpr(E);
   assert(RV.isAggregate() && "Return value must be aggregate value!");

   // If the result is ignored, don't copy from the value.
   if (DestPtr == 0)
     // FIXME: If the source is volatile, we must read from it.
     return;

   EmitAggregateCopy(DestPtr, RV.getAggregateAddr(), E->getType());
 }

 void AggExprEmitter::VisitObjCMessageExpr(ObjCMessageExpr *E) {
   RValue RV = RValue::getAggregate(CGF.EmitObjCMessageExpr(E));

   // If the result is ignored, don't copy from the value.
   if (DestPtr == 0)
     return;

   EmitAggregateCopy(DestPtr, RV.getAggregateAddr(), E->getType());
 }

 void AggExprEmitter::VisitOverloadExpr(const OverloadExpr *E) {
   RValue RV = CGF.EmitCallExpr(E->getFn(), E->arg_begin(),
                                E->arg_end(CGF.getContext()));

   assert(RV.isAggregate() && "Return value must be aggregate value!");

   // If the result is ignored, don't copy from the value.
   if (DestPtr == 0)
     // FIXME: If the source is volatile, we must read from it.
     return;

   EmitAggregateCopy(DestPtr, RV.getAggregateAddr(), E->getType());
 }

 void AggExprEmitter::VisitBinComma(const BinaryOperator *E) {
   CGF.EmitAnyExpr(E->getLHS());
   CGF.EmitAggExpr(E->getRHS(), DestPtr, false);
 }

 void AggExprEmitter::VisitStmtExpr(const StmtExpr *E) {
   CGF.EmitCompoundStmt(*E->getSubStmt(), true, DestPtr, VolatileDest);
 }

 void AggExprEmitter::VisitBinaryOperator(const BinaryOperator *E) {
   CGF.ErrorUnsupported(E, "aggregate binary expression");
 }

 void AggExprEmitter::VisitBinAssign(const BinaryOperator *E) {
   // For an assignment to work, the value on the right has
   // to be compatible with the value on the left.
   assert(CGF.getContext().typesAreCompatible(
              E->getLHS()->getType().getUnqualifiedType(),
              E->getRHS()->getType().getUnqualifiedType())
          && "Invalid assignment");
   LValue LHS = CGF.EmitLValue(E->getLHS());

   // Codegen the RHS so that it stores directly into the LHS.
   CGF.EmitAggExpr(E->getRHS(), LHS.getAddress(), false /*FIXME: VOLATILE LHS*/);

   if (DestPtr == 0)
     return;

   // If the result of the assignment is used, copy the RHS there also.
   EmitAggregateCopy(DestPtr, LHS.getAddress(), E->getType());
 }

 void AggExprEmitter::VisitConditionalOperator(const ConditionalOperator *E) {
   llvm::BasicBlock *LHSBlock = llvm::BasicBlock::Create("cond.?");
   llvm::BasicBlock *RHSBlock = llvm::BasicBlock::Create("cond.:");
   llvm::BasicBlock *ContBlock = llvm::BasicBlock::Create("cond.cont");

   llvm::Value *Cond = CGF.EvaluateExprAsBool(E->getCond());
   Builder.CreateCondBr(Cond, LHSBlock, RHSBlock);

   CGF.EmitBlock(LHSBlock);

   // Handle the GNU extension for missing LHS.
   assert(E->getLHS() && "Must have LHS for aggregate value");

   Visit(E->getLHS());
   Builder.CreateBr(ContBlock);
   LHSBlock = Builder.GetInsertBlock();

   CGF.EmitBlock(RHSBlock);

   Visit(E->getRHS());
   Builder.CreateBr(ContBlock);
   RHSBlock = Builder.GetInsertBlock();

   CGF.EmitBlock(ContBlock);
 }

 void AggExprEmitter::VisitVAArgExpr(VAArgExpr *VE) {
   llvm::Value *ArgValue = CGF.EmitLValue(VE->getSubExpr()).getAddress();
   llvm::Value *V = Builder.CreateVAArg(ArgValue, CGF.ConvertType(VE->getType()));
   if (DestPtr)
     // FIXME: volatility
     Builder.CreateStore(V, DestPtr);
 }

 void AggExprEmitter::EmitNonConstInit(InitListExpr *E) {

   const llvm::PointerType *APType =
     cast<llvm::PointerType>(DestPtr->getType());
   const llvm::Type *DestType = APType->getElementType();

   if (const llvm::ArrayType *AType = dyn_cast<llvm::ArrayType>(DestType)) {
     unsigned NumInitElements = E->getNumInits();

     unsigned i;
     for (i = 0; i != NumInitElements; ++i) {
       llvm::Value *NextVal = Builder.CreateStructGEP(DestPtr, i, ".array");
       Expr *Init = E->getInit(i);
       if (isa<InitListExpr>(Init))
         CGF.EmitAggExpr(Init, NextVal, VolatileDest);
       else
         // FIXME: volatility
         Builder.CreateStore(CGF.EmitScalarExpr(Init), NextVal);
     }

     // Emit remaining default initializers
     unsigned NumArrayElements = AType->getNumElements();
     QualType QType = E->getInit(0)->getType();
     const llvm::Type *EType = AType->getElementType();
     for (/*Do not initialize i*/; i < NumArrayElements; ++i) {
       llvm::Value *NextVal = Builder.CreateStructGEP(DestPtr, i, ".array");
       if (EType->isSingleValueType())
         // FIXME: volatility
         Builder.CreateStore(llvm::Constant::getNullValue(EType), NextVal);
       else
         EmitAggregateClear(NextVal, QType);
     }
   } else
     assert(false && "Invalid initializer");
 }

 void AggExprEmitter::EmitInitializationToLValue(Expr* E, LValue LV) {
   // FIXME: Are initializers affected by volatile?
   if (E->getType()->isComplexType()) {
     CGF.EmitComplexExprIntoAddr(E, LV.getAddress(), false);
   } else if (CGF.hasAggregateLLVMType(E->getType())) {
     CGF.EmitAnyExpr(E, LV.getAddress(), false);
   } else {
     CGF.EmitStoreThroughLValue(CGF.EmitAnyExpr(E), LV, E->getType());
   }
 }

 void AggExprEmitter::EmitNullInitializationToLValue(LValue LV, QualType T) {
   if (!CGF.hasAggregateLLVMType(T)) {
     // For non-aggregates, we can store zero
     llvm::Value *Null = llvm::Constant::getNullValue(CGF.ConvertType(T));
     CGF.EmitStoreThroughLValue(RValue::get(Null), LV, T);
   } else {
     // Otherwise, just memset the whole thing to zero.  This is legal
     // because in LLVM, all default initializers are guaranteed to have a
     // bit pattern of all zeros.
     // There's a potential optimization opportunity in combining
     // memsets; that would be easy for arrays, but relatively
     // difficult for structures with the current code.
     llvm::Value *MemSet = CGF.CGM.getIntrinsic(llvm::Intrinsic::memset_i64);
     uint64_t Size = CGF.getContext().getTypeSize(T);

     const llvm::Type *BP = llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
     llvm::Value* DestPtr = Builder.CreateBitCast(LV.getAddress(), BP, "tmp");
     Builder.CreateCall4(MemSet, DestPtr,
                         llvm::ConstantInt::get(llvm::Type::Int8Ty, 0),
                         llvm::ConstantInt::get(llvm::Type::Int64Ty, Size/8),
                         llvm::ConstantInt::get(llvm::Type::Int32Ty, 0));
   }
 }

 void AggExprEmitter::VisitInitListExpr(InitListExpr *E) {
   if (E->isConstantExpr(CGF.getContext(), 0)) {
     // FIXME: call into const expr emitter so that we can emit
     // a memcpy instead of storing the individual members.
     // This is purely for perf; both codepaths lead to equivalent
     // (although not necessarily identical) code.
     // It's worth noting that LLVM keeps on getting smarter, though,
     // so it might not be worth bothering.
   }

   // Handle initialization of an array.
   if (E->getType()->isArrayType()) {
     const llvm::PointerType *APType =
       cast<llvm::PointerType>(DestPtr->getType());
     const llvm::ArrayType *AType =
       cast<llvm::ArrayType>(APType->getElementType());

     uint64_t NumInitElements = E->getNumInits();

     if (E->getNumInits() > 0) {
       QualType T1 = E->getType();
       QualType T2 = E->getInit(0)->getType();
       if (CGF.getContext().getCanonicalType(T1).getUnqualifiedType() ==
           CGF.getContext().getCanonicalType(T2).getUnqualifiedType()) {
         EmitAggLoadOfLValue(E->getInit(0));
         return;
       }
     }

     uint64_t NumArrayElements = AType->getNumElements();
     QualType ElementType = CGF.getContext().getCanonicalType(E->getType());
     ElementType =CGF.getContext().getAsArrayType(ElementType)->getElementType();

     unsigned CVRqualifier = ElementType.getCVRQualifiers();

     for (uint64_t i = 0; i != NumArrayElements; ++i) {
       llvm::Value *NextVal = Builder.CreateStructGEP(DestPtr, i, ".array");
       if (i < NumInitElements)
         EmitInitializationToLValue(E->getInit(i),
                                    LValue::MakeAddr(NextVal, CVRqualifier));
       else
         EmitNullInitializationToLValue(LValue::MakeAddr(NextVal, CVRqualifier),
                                        ElementType);
     }
     return;
   }

   assert(E->getType()->isRecordType() && "Only support structs/unions here!");

   // Do struct initialization; this code just sets each individual member
   // to the approprate value.  This makes bitfield support automatic;
   // the disadvantage is that the generated code is more difficult for
   // the optimizer, especially with bitfields.
   unsigned NumInitElements = E->getNumInits();
   RecordDecl *SD = E->getType()->getAsRecordType()->getDecl();
   unsigned NumMembers = SD->getNumMembers() - SD->hasFlexibleArrayMember();
   unsigned CurInitVal = 0;
   bool isUnion = E->getType()->isUnionType();

   // Here we iterate over the fields; this makes it simpler to both
   // default-initialize fields and skip over unnamed fields.
   for (unsigned CurFieldNo = 0; CurFieldNo != NumMembers; ++CurFieldNo) {
     FieldDecl *CurField = SD->getMember(CurFieldNo);
     if (CurField->getIdentifier() == 0) {
       // Initializers can't initialize unnamed fields, e.g. "int : 20;"
       continue;
     }
     // FIXME: volatility
     LValue FieldLoc = CGF.EmitLValueForField(DestPtr, CurField, isUnion,0);
     if (CurInitVal < NumInitElements) {
       // Store the initializer into the field
       // This will probably have to get a bit smarter when we support
       // designators in initializers
       EmitInitializationToLValue(E->getInit(CurInitVal++), FieldLoc);
     } else {
       // We're out of initalizers; default-initialize to null
       EmitNullInitializationToLValue(FieldLoc, CurField->getType());
     }

     // Unions only initialize one field.
     // (things can get weird with designators, but they aren't
     // supported yet.)
     if (E->getType()->isUnionType())
       break;
   }
 }

 //===----------------------------------------------------------------------===//
 //                        Entry Points into this File
 //===----------------------------------------------------------------------===//

 /// EmitAggExpr - Emit the computation of the specified expression of
 /// aggregate type.  The result is computed into DestPtr.  Note that if
 /// DestPtr is null, the value of the aggregate expression is not needed.
 void CodeGenFunction::EmitAggExpr(const Expr *E, llvm::Value *DestPtr,
                                   bool VolatileDest) {
   assert(E && hasAggregateLLVMType(E->getType()) &&
          "Invalid aggregate expression to emit");

   AggExprEmitter(*this, DestPtr, VolatileDest).Visit(const_cast<Expr*>(E));
 }
	//===--- CGExprAgg.cpp - Emit LLVM Code from Aggregate Expressions --------===//
	//
	// The LLVM Compiler Infrastructure
	//
	// This file is distributed under the University of Illinois Open Source
	// License. See LICENSE.TXT for details.
	//
	//===----------------------------------------------------------------------===//
	//
	// This contains code to emit Aggregate Expr nodes as LLVM code.
	//
	//===----------------------------------------------------------------------===//

	#include "CodeGenFunction.h"
	#include "CodeGenModule.h"
	#include "clang/AST/ASTContext.h"
	#include "clang/AST/StmtVisitor.h"
	#include "llvm/Constants.h"
	#include "llvm/Function.h"
	#include "llvm/GlobalVariable.h"
	#include "llvm/Support/Compiler.h"
	#include "llvm/Intrinsics.h"
	using namespace clang;
	using namespace CodeGen;

	//===----------------------------------------------------------------------===//
	// Aggregate Expression Emitter
	//===----------------------------------------------------------------------===//

	namespace {
	class VISIBILITY_HIDDEN AggExprEmitter : public StmtVisitor<AggExprEmitter> {
	CodeGenFunction &CGF;
	llvm::IRBuilder<> &Builder;
	llvm::Value *DestPtr;
	bool VolatileDest;
	public:
	AggExprEmitter(CodeGenFunction &cgf, llvm::Value *destPtr, bool volatileDest)
	: CGF(cgf), Builder(CGF.Builder),
	DestPtr(destPtr), VolatileDest(volatileDest) {
	}

	//===--------------------------------------------------------------------===//
	// Utilities
	//===--------------------------------------------------------------------===//

	/// EmitAggLoadOfLValue - Given an expression with aggregate type that
	/// represents a value lvalue, this method emits the address of the lvalue,
	/// then loads the result into DestPtr.
	void EmitAggLoadOfLValue(const Expr *E);

	void EmitAggregateCopy(llvm::Value DestPtr, llvm::Value SrcPtr,
	QualType EltTy);

	void EmitAggregateClear(llvm::Value *DestPtr, QualType Ty);

	void EmitNonConstInit(InitListExpr *E);

	//===--------------------------------------------------------------------===//
	// Visitor Methods
	//===--------------------------------------------------------------------===//

	void VisitStmt(Stmt *S) {
	CGF.ErrorUnsupported(S, "aggregate expression");
	}
	void VisitParenExpr(ParenExpr *PE) { Visit(PE->getSubExpr()); }

	// l-values.
	void VisitDeclRefExpr(DeclRefExpr *DRE) { EmitAggLoadOfLValue(DRE); }
	void VisitMemberExpr(MemberExpr *ME) { EmitAggLoadOfLValue(ME); }
	void VisitUnaryDeref(UnaryOperator *E) { EmitAggLoadOfLValue(E); }
	void VisitStringLiteral(StringLiteral *E) { EmitAggLoadOfLValue(E); }
	void VisitCompoundLiteralExpr(CompoundLiteralExpr *E)
	{ EmitAggLoadOfLValue(E); }

	void VisitArraySubscriptExpr(ArraySubscriptExpr *E) {
	EmitAggLoadOfLValue(E);
	}

	// Operators.
	// case Expr::UnaryOperatorClass:
	// case Expr::CastExprClass:
	void VisitImplicitCastExpr(ImplicitCastExpr *E);
	void VisitCallExpr(const CallExpr *E);
	void VisitStmtExpr(const StmtExpr *E);
	void VisitBinaryOperator(const BinaryOperator *BO);
	void VisitBinAssign(const BinaryOperator *E);
	void VisitOverloadExpr(const OverloadExpr *E);
	void VisitBinComma(const BinaryOperator *E);

	void VisitObjCMessageExpr(ObjCMessageExpr *E);


	void VisitConditionalOperator(const ConditionalOperator *CO);
	void VisitInitListExpr(InitListExpr *E);
	void VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) {
	Visit(DAE->getExpr());
	}
	void VisitVAArgExpr(VAArgExpr *E);

	void EmitInitializationToLValue(Expr *E, LValue Address);
	void EmitNullInitializationToLValue(LValue Address, QualType T);
	// case Expr::ChooseExprClass:

	};
	} // end anonymous namespace.

	//===----------------------------------------------------------------------===//
	// Utilities
	//===----------------------------------------------------------------------===//

	void AggExprEmitter::EmitAggregateClear(llvm::Value *DestPtr, QualType Ty) {
	assert(!Ty->isAnyComplexType() && "Shouldn't happen for complex");

	// Aggregate assignment turns into llvm.memset.
	const llvm::Type *BP = llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
	if (DestPtr->getType() != BP)
	DestPtr = Builder.CreateBitCast(DestPtr, BP, "tmp");

	// Get size and alignment info for this aggregate.
	std::pair<uint64_t, unsigned> TypeInfo = CGF.getContext().getTypeInfo(Ty);

	// FIXME: Handle variable sized types.
	const llvm::Type *IntPtr = llvm::IntegerType::get(CGF.LLVMPointerWidth);

	llvm::Value *MemSetOps[4] = {
	DestPtr,
	llvm::ConstantInt::getNullValue(llvm::Type::Int8Ty),
	// TypeInfo.first describes size in bits.
	llvm::ConstantInt::get(IntPtr, TypeInfo.first/8),
	llvm::ConstantInt::get(llvm::Type::Int32Ty, TypeInfo.second/8)
	};

	Builder.CreateCall(CGF.CGM.getMemSetFn(), MemSetOps, MemSetOps+4);
	}

	void AggExprEmitter::EmitAggregateCopy(llvm::Value *DestPtr,
	llvm::Value *SrcPtr, QualType Ty) {
	assert(!Ty->isAnyComplexType() && "Shouldn't happen for complex");

	// Aggregate assignment turns into llvm.memmove.
	const llvm::Type *BP = llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
	if (DestPtr->getType() != BP)
	DestPtr = Builder.CreateBitCast(DestPtr, BP, "tmp");
	if (SrcPtr->getType() != BP)
	SrcPtr = Builder.CreateBitCast(SrcPtr, BP, "tmp");

	// Get size and alignment info for this aggregate.
	std::pair<uint64_t, unsigned> TypeInfo = CGF.getContext().getTypeInfo(Ty);

	// FIXME: Handle variable sized types.
	const llvm::Type *IntPtr = llvm::IntegerType::get(CGF.LLVMPointerWidth);

	llvm::Value *MemMoveOps[4] = {
	DestPtr, SrcPtr,
	// TypeInfo.first describes size in bits.
	llvm::ConstantInt::get(IntPtr, TypeInfo.first/8),
	llvm::ConstantInt::get(llvm::Type::Int32Ty, TypeInfo.second/8)
	};

	Builder.CreateCall(CGF.CGM.getMemMoveFn(), MemMoveOps, MemMoveOps+4);
	}


	/// EmitAggLoadOfLValue - Given an expression with aggregate type that
	/// represents a value lvalue, this method emits the address of the lvalue,
	/// then loads the result into DestPtr.
	void AggExprEmitter::EmitAggLoadOfLValue(const Expr *E) {
	LValue LV = CGF.EmitLValue(E);
	assert(LV.isSimple() && "Can't have aggregate bitfield, vector, etc");
	llvm::Value *SrcPtr = LV.getAddress();

	// If the result is ignored, don't copy from the value.
	if (DestPtr == 0)
	// FIXME: If the source is volatile, we must read from it.
	return;

	EmitAggregateCopy(DestPtr, SrcPtr, E->getType());
	}

	//===----------------------------------------------------------------------===//
	// Visitor Methods
	//===----------------------------------------------------------------------===//

	void AggExprEmitter::VisitImplicitCastExpr(ImplicitCastExpr *E) {
	assert(CGF.getContext().typesAreCompatible(
	E->getSubExpr()->getType().getUnqualifiedType(),
	E->getType().getUnqualifiedType()) &&
	"Implicit cast types must be compatible");
	Visit(E->getSubExpr());
	}

	void AggExprEmitter::VisitCallExpr(const CallExpr *E) {
	RValue RV = CGF.EmitCallExpr(E);
	assert(RV.isAggregate() && "Return value must be aggregate value!");

	// If the result is ignored, don't copy from the value.
	if (DestPtr == 0)
	// FIXME: If the source is volatile, we must read from it.
	return;

	EmitAggregateCopy(DestPtr, RV.getAggregateAddr(), E->getType());
	}

	void AggExprEmitter::VisitObjCMessageExpr(ObjCMessageExpr *E) {
	RValue RV = RValue::getAggregate(CGF.EmitObjCMessageExpr(E));

	// If the result is ignored, don't copy from the value.
	if (DestPtr == 0)
	return;

	EmitAggregateCopy(DestPtr, RV.getAggregateAddr(), E->getType());
	}

	void AggExprEmitter::VisitOverloadExpr(const OverloadExpr *E) {
	RValue RV = CGF.EmitCallExpr(E->getFn(), E->arg_begin(),
	E->arg_end(CGF.getContext()));

	assert(RV.isAggregate() && "Return value must be aggregate value!");

	// If the result is ignored, don't copy from the value.
	if (DestPtr == 0)
	// FIXME: If the source is volatile, we must read from it.
	return;

	EmitAggregateCopy(DestPtr, RV.getAggregateAddr(), E->getType());
	}

	void AggExprEmitter::VisitBinComma(const BinaryOperator *E) {
	CGF.EmitAnyExpr(E->getLHS());
	CGF.EmitAggExpr(E->getRHS(), DestPtr, false);
	}

	void AggExprEmitter::VisitStmtExpr(const StmtExpr *E) {
	CGF.EmitCompoundStmt(*E->getSubStmt(), true, DestPtr, VolatileDest);
	}

	void AggExprEmitter::VisitBinaryOperator(const BinaryOperator *E) {
	CGF.ErrorUnsupported(E, "aggregate binary expression");
	}

	void AggExprEmitter::VisitBinAssign(const BinaryOperator *E) {
	// For an assignment to work, the value on the right has
	// to be compatible with the value on the left.
	assert(CGF.getContext().typesAreCompatible(
	E->getLHS()->getType().getUnqualifiedType(),
	E->getRHS()->getType().getUnqualifiedType())
	&& "Invalid assignment");
	LValue LHS = CGF.EmitLValue(E->getLHS());

	// Codegen the RHS so that it stores directly into the LHS.
	CGF.EmitAggExpr(E->getRHS(), LHS.getAddress(), false /FIXME: VOLATILE LHS/);

	if (DestPtr == 0)
	return;

	// If the result of the assignment is used, copy the RHS there also.
	EmitAggregateCopy(DestPtr, LHS.getAddress(), E->getType());
	}

	void AggExprEmitter::VisitConditionalOperator(const ConditionalOperator *E) {
	llvm::BasicBlock *LHSBlock = llvm::BasicBlock::Create("cond.?");
	llvm::BasicBlock *RHSBlock = llvm::BasicBlock::Create("cond.:");
	llvm::BasicBlock *ContBlock = llvm::BasicBlock::Create("cond.cont");

	llvm::Value *Cond = CGF.EvaluateExprAsBool(E->getCond());
	Builder.CreateCondBr(Cond, LHSBlock, RHSBlock);

	CGF.EmitBlock(LHSBlock);

	// Handle the GNU extension for missing LHS.
	assert(E->getLHS() && "Must have LHS for aggregate value");

	Visit(E->getLHS());
	Builder.CreateBr(ContBlock);
	LHSBlock = Builder.GetInsertBlock();

	CGF.EmitBlock(RHSBlock);

	Visit(E->getRHS());
	Builder.CreateBr(ContBlock);
	RHSBlock = Builder.GetInsertBlock();

	CGF.EmitBlock(ContBlock);
	}

	void AggExprEmitter::VisitVAArgExpr(VAArgExpr *VE) {
	llvm::Value *ArgValue = CGF.EmitLValue(VE->getSubExpr()).getAddress();
	llvm::Value *V = Builder.CreateVAArg(ArgValue, CGF.ConvertType(VE->getType()));
	if (DestPtr)
	// FIXME: volatility
	Builder.CreateStore(V, DestPtr);
	}

	void AggExprEmitter::EmitNonConstInit(InitListExpr *E) {

	const llvm::PointerType *APType =
	cast<llvm::PointerType>(DestPtr->getType());
	const llvm::Type *DestType = APType->getElementType();

	if (const llvm::ArrayType *AType = dyn_cast<llvm::ArrayType>(DestType)) {
	unsigned NumInitElements = E->getNumInits();

	unsigned i;
	for (i = 0; i != NumInitElements; ++i) {
	llvm::Value *NextVal = Builder.CreateStructGEP(DestPtr, i, ".array");
	Expr *Init = E->getInit(i);
	if (isa<InitListExpr>(Init))
	CGF.EmitAggExpr(Init, NextVal, VolatileDest);
	else
	// FIXME: volatility
	Builder.CreateStore(CGF.EmitScalarExpr(Init), NextVal);
	}

	// Emit remaining default initializers
	unsigned NumArrayElements = AType->getNumElements();
	QualType QType = E->getInit(0)->getType();
	const llvm::Type *EType = AType->getElementType();
	for (/Do not initialize i/; i < NumArrayElements; ++i) {
	llvm::Value *NextVal = Builder.CreateStructGEP(DestPtr, i, ".array");
	if (EType->isSingleValueType())
	// FIXME: volatility
	Builder.CreateStore(llvm::Constant::getNullValue(EType), NextVal);
	else
	EmitAggregateClear(NextVal, QType);
	}
	} else
	assert(false && "Invalid initializer");
	}

	void AggExprEmitter::EmitInitializationToLValue(Expr* E, LValue LV) {
	// FIXME: Are initializers affected by volatile?
	if (E->getType()->isComplexType()) {
	CGF.EmitComplexExprIntoAddr(E, LV.getAddress(), false);
	} else if (CGF.hasAggregateLLVMType(E->getType())) {
	CGF.EmitAnyExpr(E, LV.getAddress(), false);
	} else {
	CGF.EmitStoreThroughLValue(CGF.EmitAnyExpr(E), LV, E->getType());
	}
	}

	void AggExprEmitter::EmitNullInitializationToLValue(LValue LV, QualType T) {
	if (!CGF.hasAggregateLLVMType(T)) {
	// For non-aggregates, we can store zero
	llvm::Value *Null = llvm::Constant::getNullValue(CGF.ConvertType(T));
	CGF.EmitStoreThroughLValue(RValue::get(Null), LV, T);
	} else {
	// Otherwise, just memset the whole thing to zero. This is legal
	// because in LLVM, all default initializers are guaranteed to have a
	// bit pattern of all zeros.
	// There's a potential optimization opportunity in combining
	// memsets; that would be easy for arrays, but relatively
	// difficult for structures with the current code.
	llvm::Value *MemSet = CGF.CGM.getIntrinsic(llvm::Intrinsic::memset_i64);
	uint64_t Size = CGF.getContext().getTypeSize(T);

	const llvm::Type *BP = llvm::PointerType::getUnqual(llvm::Type::Int8Ty);
	llvm::Value* DestPtr = Builder.CreateBitCast(LV.getAddress(), BP, "tmp");
	Builder.CreateCall4(MemSet, DestPtr,
	llvm::ConstantInt::get(llvm::Type::Int8Ty, 0),
	llvm::ConstantInt::get(llvm::Type::Int64Ty, Size/8),
	llvm::ConstantInt::get(llvm::Type::Int32Ty, 0));
	}
	}

	void AggExprEmitter::VisitInitListExpr(InitListExpr *E) {
	if (E->isConstantExpr(CGF.getContext(), 0)) {
	// FIXME: call into const expr emitter so that we can emit
	// a memcpy instead of storing the individual members.
	// This is purely for perf; both codepaths lead to equivalent
	// (although not necessarily identical) code.
	// It's worth noting that LLVM keeps on getting smarter, though,
	// so it might not be worth bothering.
	}

	// Handle initialization of an array.
	if (E->getType()->isArrayType()) {
	const llvm::PointerType *APType =
	cast<llvm::PointerType>(DestPtr->getType());
	const llvm::ArrayType *AType =
	cast<llvm::ArrayType>(APType->getElementType());

	uint64_t NumInitElements = E->getNumInits();

	if (E->getNumInits() > 0) {
	QualType T1 = E->getType();
	QualType T2 = E->getInit(0)->getType();
	if (CGF.getContext().getCanonicalType(T1).getUnqualifiedType() ==
	CGF.getContext().getCanonicalType(T2).getUnqualifiedType()) {
	EmitAggLoadOfLValue(E->getInit(0));
	return;
	}
	}

	uint64_t NumArrayElements = AType->getNumElements();
	QualType ElementType = CGF.getContext().getCanonicalType(E->getType());
	ElementType =CGF.getContext().getAsArrayType(ElementType)->getElementType();

	unsigned CVRqualifier = ElementType.getCVRQualifiers();

	for (uint64_t i = 0; i != NumArrayElements; ++i) {
	llvm::Value *NextVal = Builder.CreateStructGEP(DestPtr, i, ".array");
	if (i < NumInitElements)
	EmitInitializationToLValue(E->getInit(i),
	LValue::MakeAddr(NextVal, CVRqualifier));
	else
	EmitNullInitializationToLValue(LValue::MakeAddr(NextVal, CVRqualifier),
	ElementType);
	}
	return;
	}

	assert(E->getType()->isRecordType() && "Only support structs/unions here!");

	// Do struct initialization; this code just sets each individual member
	// to the approprate value. This makes bitfield support automatic;
	// the disadvantage is that the generated code is more difficult for
	// the optimizer, especially with bitfields.
	unsigned NumInitElements = E->getNumInits();
	RecordDecl *SD = E->getType()->getAsRecordType()->getDecl();
	unsigned NumMembers = SD->getNumMembers() - SD->hasFlexibleArrayMember();
	unsigned CurInitVal = 0;
	bool isUnion = E->getType()->isUnionType();

	// Here we iterate over the fields; this makes it simpler to both
	// default-initialize fields and skip over unnamed fields.
	for (unsigned CurFieldNo = 0; CurFieldNo != NumMembers; ++CurFieldNo) {
	FieldDecl *CurField = SD->getMember(CurFieldNo);
	if (CurField->getIdentifier() == 0) {
	// Initializers can't initialize unnamed fields, e.g. "int : 20;"
	continue;
	}
	// FIXME: volatility
	LValue FieldLoc = CGF.EmitLValueForField(DestPtr, CurField, isUnion,0);
	if (CurInitVal < NumInitElements) {
	// Store the initializer into the field
	// This will probably have to get a bit smarter when we support
	// designators in initializers
	EmitInitializationToLValue(E->getInit(CurInitVal++), FieldLoc);
	} else {
	// We're out of initalizers; default-initialize to null
	EmitNullInitializationToLValue(FieldLoc, CurField->getType());
	}

	// Unions only initialize one field.
	// (things can get weird with designators, but they aren't
	// supported yet.)
	if (E->getType()->isUnionType())
	break;
	}
	}

	//===----------------------------------------------------------------------===//
	// Entry Points into this File
	//===----------------------------------------------------------------------===//

	/// EmitAggExpr - Emit the computation of the specified expression of
	/// aggregate type. The result is computed into DestPtr. Note that if
	/// DestPtr is null, the value of the aggregate expression is not needed.
	void CodeGenFunction::EmitAggExpr(const Expr E, llvm::Value DestPtr,
	bool VolatileDest) {
	assert(E && hasAggregateLLVMType(E->getType()) &&
	"Invalid aggregate expression to emit");

	AggExprEmitter(this, DestPtr, VolatileDest).Visit(const_cast<Expr>(E));
	}