lib/Analysis/SimpleSValuator.cpp - fp2-dev/platform/external/clang - Gitiles

 // SimpleSValuator.cpp - A basic SValuator ------------------------*- C++ -*--//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 //  This file defines SimpleSValuator, a basic implementation of SValuator.
 //
 //===----------------------------------------------------------------------===//

 #include "clang/Analysis/PathSensitive/SValuator.h"
 #include "clang/Analysis/PathSensitive/GRState.h"
 #include "llvm/Support/Compiler.h"

 using namespace clang;

 namespace {
 class VISIBILITY_HIDDEN SimpleSValuator : public SValuator {
 protected:
   virtual SVal EvalCastNL(NonLoc val, QualType castTy);
   virtual SVal EvalCastL(Loc val, QualType castTy);

 public:
   SimpleSValuator(ValueManager &valMgr) : SValuator(valMgr) {}
   virtual ~SimpleSValuator() {}

   virtual SVal EvalMinus(NonLoc val);
   virtual SVal EvalComplement(NonLoc val);
   virtual SVal EvalBinOpNN(const GRState *state, BinaryOperator::Opcode op,
                            NonLoc lhs, NonLoc rhs, QualType resultTy);
   virtual SVal EvalBinOpLL(BinaryOperator::Opcode op, Loc lhs, Loc rhs,
                            QualType resultTy);
   virtual SVal EvalBinOpLN(const GRState *state, BinaryOperator::Opcode op,
                            Loc lhs, NonLoc rhs, QualType resultTy);
 };
 } // end anonymous namespace

 SValuator *clang::CreateSimpleSValuator(ValueManager &valMgr) {
   return new SimpleSValuator(valMgr);
 }

 //===----------------------------------------------------------------------===//
 // Transfer function for Casts.
 //===----------------------------------------------------------------------===//

 SVal SimpleSValuator::EvalCastNL(NonLoc val, QualType castTy) {

   bool isLocType = Loc::IsLocType(castTy);

   if (nonloc::LocAsInteger *LI = dyn_cast<nonloc::LocAsInteger>(&val)) {
     if (isLocType)
       return LI->getLoc();

     ASTContext &Ctx = ValMgr.getContext();

     // FIXME: Support promotions/truncations.
     if (Ctx.getTypeSize(castTy) == Ctx.getTypeSize(Ctx.VoidPtrTy))
       return val;

     return UnknownVal();
   }

   if (const SymExpr *se = val.getAsSymbolicExpression()) {
     ASTContext &Ctx = ValMgr.getContext();
     QualType T = Ctx.getCanonicalType(se->getType(Ctx));
     if (T == Ctx.getCanonicalType(castTy))
       return val;

     // FIXME: Remove this hack when we support symbolic truncation/extension.
     // HACK: If both castTy and T are integers, ignore the cast.  This is
     // not a permanent solution.  Eventually we want to precisely handle
     // extension/truncation of symbolic integers.  This prevents us from losing
     // precision when we assign 'x = y' and 'y' is symbolic and x and y are
     // different integer types.
     if (T->isIntegerType() && castTy->isIntegerType())
       return val;

     return UnknownVal();
   }

   if (!isa<nonloc::ConcreteInt>(val))
     return UnknownVal();

   // Only handle casts from integers to integers.
   if (!isLocType && !castTy->isIntegerType())
     return UnknownVal();

   llvm::APSInt i = cast<nonloc::ConcreteInt>(val).getValue();
   i.setIsUnsigned(castTy->isUnsignedIntegerType() || Loc::IsLocType(castTy));
   i.extOrTrunc(ValMgr.getContext().getTypeSize(castTy));

   if (isLocType)
     return ValMgr.makeIntLocVal(i);
   else
     return ValMgr.makeIntVal(i);
 }

 SVal SimpleSValuator::EvalCastL(Loc val, QualType castTy) {

   // Casts from pointers -> pointers, just return the lval.
   //
   // Casts from pointers -> references, just return the lval.  These
   //   can be introduced by the frontend for corner cases, e.g
   //   casting from va_list* to __builtin_va_list&.
   //
   if (Loc::IsLocType(castTy) || castTy->isReferenceType())
     return val;

   // FIXME: Handle transparent unions where a value can be "transparently"
   //  lifted into a union type.
   if (castTy->isUnionType())
     return UnknownVal();

   assert(castTy->isIntegerType());
   unsigned BitWidth = ValMgr.getContext().getTypeSize(castTy);

   if (!isa<loc::ConcreteInt>(val))
     return ValMgr.makeLocAsInteger(val, BitWidth);

   llvm::APSInt i = cast<loc::ConcreteInt>(val).getValue();
   i.setIsUnsigned(castTy->isUnsignedIntegerType() || Loc::IsLocType(castTy));
   i.extOrTrunc(BitWidth);
   return ValMgr.makeIntVal(i);
 }

 //===----------------------------------------------------------------------===//
 // Transfer function for unary operators.
 //===----------------------------------------------------------------------===//

 SVal SimpleSValuator::EvalMinus(NonLoc val) {
   switch (val.getSubKind()) {
   case nonloc::ConcreteIntKind:
     return cast<nonloc::ConcreteInt>(val).evalMinus(ValMgr);
   default:
     return UnknownVal();
   }
 }

 SVal SimpleSValuator::EvalComplement(NonLoc X) {
   switch (X.getSubKind()) {
   case nonloc::ConcreteIntKind:
     return cast<nonloc::ConcreteInt>(X).evalComplement(ValMgr);
   default:
     return UnknownVal();
   }
 }

 //===----------------------------------------------------------------------===//
 // Transfer function for binary operators.
 //===----------------------------------------------------------------------===//

 static BinaryOperator::Opcode NegateComparison(BinaryOperator::Opcode op) {
   switch (op) {
   default:
     assert(false && "Invalid opcode.");
   case BinaryOperator::LT: return BinaryOperator::GE;
   case BinaryOperator::GT: return BinaryOperator::LE;
   case BinaryOperator::LE: return BinaryOperator::GT;
   case BinaryOperator::GE: return BinaryOperator::LT;
   case BinaryOperator::EQ: return BinaryOperator::NE;
   case BinaryOperator::NE: return BinaryOperator::EQ;
   }
 }

 // Equality operators for Locs.
 // FIXME: All this logic will be revamped when we have MemRegion::getLocation()
 // implemented.

 static SVal EvalEquality(ValueManager &ValMgr, Loc lhs, Loc rhs, bool isEqual,
                          QualType resultTy) {

   switch (lhs.getSubKind()) {
     default:
       assert(false && "EQ/NE not implemented for this Loc.");
       return UnknownVal();

     case loc::ConcreteIntKind: {
       if (SymbolRef rSym = rhs.getAsSymbol())
         return ValMgr.makeNonLoc(rSym,
                                  isEqual ? BinaryOperator::EQ
                                  : BinaryOperator::NE,
                                  cast<loc::ConcreteInt>(lhs).getValue(),
                                  resultTy);
       break;
     }
     case loc::MemRegionKind: {
       if (SymbolRef lSym = lhs.getAsLocSymbol()) {
         if (isa<loc::ConcreteInt>(rhs)) {
           return ValMgr.makeNonLoc(lSym,
                                    isEqual ? BinaryOperator::EQ
                                    : BinaryOperator::NE,
                                    cast<loc::ConcreteInt>(rhs).getValue(),
                                    resultTy);
         }
       }
       break;
     }

     case loc::GotoLabelKind:
       break;
   }

   return ValMgr.makeTruthVal(isEqual ? lhs == rhs : lhs != rhs, resultTy);
 }

 SVal SimpleSValuator::EvalBinOpNN(const GRState *state,
                                   BinaryOperator::Opcode op,
                                   NonLoc lhs, NonLoc rhs,
                                   QualType resultTy)  {
   // Handle trivial case where left-side and right-side are the same.
   if (lhs == rhs)
     switch (op) {
       default:
         break;
       case BinaryOperator::EQ:
       case BinaryOperator::LE:
       case BinaryOperator::GE:
         return ValMgr.makeTruthVal(true, resultTy);
       case BinaryOperator::LT:
       case BinaryOperator::GT:
       case BinaryOperator::NE:
         return ValMgr.makeTruthVal(false, resultTy);
     }

   while (1) {
     switch (lhs.getSubKind()) {
     default:
       return UnknownVal();
     case nonloc::LocAsIntegerKind: {
       Loc lhsL = cast<nonloc::LocAsInteger>(lhs).getLoc();
       switch (rhs.getSubKind()) {
         case nonloc::LocAsIntegerKind:
           return EvalBinOpLL(op, lhsL, cast<nonloc::LocAsInteger>(rhs).getLoc(),
                              resultTy);
         case nonloc::ConcreteIntKind: {
           // Transform the integer into a location and compare.
           ASTContext& Ctx = ValMgr.getContext();
           llvm::APSInt i = cast<nonloc::ConcreteInt>(rhs).getValue();
           i.setIsUnsigned(true);
           i.extOrTrunc(Ctx.getTypeSize(Ctx.VoidPtrTy));
           return EvalBinOpLL(op, lhsL, ValMgr.makeLoc(i), resultTy);
         }
         default:
           switch (op) {
             case BinaryOperator::EQ:
               return ValMgr.makeTruthVal(false, resultTy);
             case BinaryOperator::NE:
               return ValMgr.makeTruthVal(true, resultTy);
             default:
               // This case also handles pointer arithmetic.
               return UnknownVal();
           }
       }
     }
     case nonloc::SymExprValKind: {
       // Logical not?
       if (!(op == BinaryOperator::EQ && rhs.isZeroConstant()))
         return UnknownVal();

       const SymExpr *symExpr =
         cast<nonloc::SymExprVal>(lhs).getSymbolicExpression();

       // Only handle ($sym op constant) for now.
       if (const SymIntExpr *symIntExpr = dyn_cast<SymIntExpr>(symExpr)) {
         BinaryOperator::Opcode opc = symIntExpr->getOpcode();
         switch (opc) {
           case BinaryOperator::LAnd:
           case BinaryOperator::LOr:
             assert(false && "Logical operators handled by branching logic.");
             return UnknownVal();
           case BinaryOperator::Assign:
           case BinaryOperator::MulAssign:
           case BinaryOperator::DivAssign:
           case BinaryOperator::RemAssign:
           case BinaryOperator::AddAssign:
           case BinaryOperator::SubAssign:
           case BinaryOperator::ShlAssign:
           case BinaryOperator::ShrAssign:
           case BinaryOperator::AndAssign:
           case BinaryOperator::XorAssign:
           case BinaryOperator::OrAssign:
           case BinaryOperator::Comma:
             assert(false && "'=' and ',' operators handled by GRExprEngine.");
             return UnknownVal();
           case BinaryOperator::PtrMemD:
           case BinaryOperator::PtrMemI:
             assert(false && "Pointer arithmetic not handled here.");
             return UnknownVal();
           case BinaryOperator::Mul:
           case BinaryOperator::Div:
           case BinaryOperator::Rem:
           case BinaryOperator::Add:
           case BinaryOperator::Sub:
           case BinaryOperator::Shl:
           case BinaryOperator::Shr:
           case BinaryOperator::And:
           case BinaryOperator::Xor:
           case BinaryOperator::Or:
             // Not handled yet.
             return UnknownVal();
           case BinaryOperator::LT:
           case BinaryOperator::GT:
           case BinaryOperator::LE:
           case BinaryOperator::GE:
           case BinaryOperator::EQ:
           case BinaryOperator::NE:
             opc = NegateComparison(opc);
             assert(symIntExpr->getType(ValMgr.getContext()) == resultTy);
             return ValMgr.makeNonLoc(symIntExpr->getLHS(), opc,
                                      symIntExpr->getRHS(), resultTy);
         }
       }
     }
     case nonloc::ConcreteIntKind: {
       if (isa<nonloc::ConcreteInt>(rhs)) {
         const nonloc::ConcreteInt& lhsInt = cast<nonloc::ConcreteInt>(lhs);
         return lhsInt.evalBinOp(ValMgr, op, cast<nonloc::ConcreteInt>(rhs));
       }
       else {
         // Swap the left and right sides and flip the operator if doing so
         // allows us to better reason about the expression (this is a form
         // of expression canonicalization).
         NonLoc tmp = rhs;
         rhs = lhs;
         lhs = tmp;

         switch (op) {
           case BinaryOperator::LT: op = BinaryOperator::GT; continue;
           case BinaryOperator::GT: op = BinaryOperator::LT; continue;
           case BinaryOperator::LE: op = BinaryOperator::GE; continue;
           case BinaryOperator::GE: op = BinaryOperator::LE; continue;
           case BinaryOperator::EQ:
           case BinaryOperator::NE:
           case BinaryOperator::Add:
           case BinaryOperator::Mul:
             continue;
           default:
             return UnknownVal();
         }
       }
     }
     case nonloc::SymbolValKind: {
       nonloc::SymbolVal *slhs = cast<nonloc::SymbolVal>(&lhs);
       SymbolRef Sym = slhs->getSymbol();

       // Does the symbol simplify to a constant?  If so, "fold" the constant
       // by setting 'lhs' to a ConcreteInt and try again.
       if (Sym->getType(ValMgr.getContext())->isIntegerType())
         if (const llvm::APSInt *Constant = state->getSymVal(Sym)) {
           // The symbol evaluates to a constant. If necessary, promote the
           // folded constant (LHS) to the result type.
           BasicValueFactory &BVF = ValMgr.getBasicValueFactory();
           const llvm::APSInt &lhs_I = BVF.Convert(resultTy, *Constant);
           lhs = nonloc::ConcreteInt(lhs_I);

           // Also promote the RHS (if necessary).

           // For shifts, it necessary promote the RHS to the result type.
           if (BinaryOperator::isShiftOp(op))
             continue;

           // Other operators: do an implicit conversion.  This shouldn't be
           // necessary once we support truncation/extension of symbolic values.
           if (nonloc::ConcreteInt *rhs_I = dyn_cast<nonloc::ConcreteInt>(&rhs)){
             rhs = nonloc::ConcreteInt(BVF.Convert(resultTy, rhs_I->getValue()));
           }

           continue;
         }

       if (isa<nonloc::ConcreteInt>(rhs)) {
         return ValMgr.makeNonLoc(slhs->getSymbol(), op,
                                  cast<nonloc::ConcreteInt>(rhs).getValue(),
                                  resultTy);
       }

       return UnknownVal();
     }
     }
   }
 }

 SVal SimpleSValuator::EvalBinOpLL(BinaryOperator::Opcode op, Loc lhs, Loc rhs,
                                   QualType resultTy) {
   switch (op) {
     default:
       return UnknownVal();
     case BinaryOperator::EQ:
     case BinaryOperator::NE:
       return EvalEquality(ValMgr, lhs, rhs, op == BinaryOperator::EQ, resultTy);
     case BinaryOperator::LT:
     case BinaryOperator::GT:
       // FIXME: Generalize.  For now, just handle the trivial case where
       //  the two locations are identical.
       if (lhs == rhs)
         return ValMgr.makeTruthVal(false, resultTy);
       return UnknownVal();
   }
 }

 SVal SimpleSValuator::EvalBinOpLN(const GRState *state,
                                   BinaryOperator::Opcode op,
                                   Loc lhs, NonLoc rhs, QualType resultTy) {
   // Special case: 'rhs' is an integer that has the same width as a pointer and
   // we are using the integer location in a comparison.  Normally this cannot be
   // triggered, but transfer functions like those for OSCommpareAndSwapBarrier32
   // can generate comparisons that trigger this code.
   // FIXME: Are all locations guaranteed to have pointer width?
   if (BinaryOperator::isEqualityOp(op)) {
     if (nonloc::ConcreteInt *rhsInt = dyn_cast<nonloc::ConcreteInt>(&rhs)) {
       const llvm::APSInt *x = &rhsInt->getValue();
       ASTContext &ctx = ValMgr.getContext();
       if (ctx.getTypeSize(ctx.VoidPtrTy) == x->getBitWidth()) {
         // Convert the signedness of the integer (if necessary).
         if (x->isSigned())
           x = &ValMgr.getBasicValueFactory().getValue(*x, true);

         return EvalBinOpLL(op, lhs, loc::ConcreteInt(*x), resultTy);
       }
     }
   }

   // Delegate pointer arithmetic to the StoreManager.
   return state->getStateManager().getStoreManager().EvalBinOp(state, op, lhs,
                                                               rhs, resultTy);
 }
	// SimpleSValuator.cpp - A basic SValuator ------------------------- C++ ---//
	//
	// The LLVM Compiler Infrastructure
	//
	// This file is distributed under the University of Illinois Open Source
	// License. See LICENSE.TXT for details.
	//
	//===----------------------------------------------------------------------===//
	//
	// This file defines SimpleSValuator, a basic implementation of SValuator.
	//
	//===----------------------------------------------------------------------===//

	#include "clang/Analysis/PathSensitive/SValuator.h"
	#include "clang/Analysis/PathSensitive/GRState.h"
	#include "llvm/Support/Compiler.h"

	using namespace clang;

	namespace {
	class VISIBILITY_HIDDEN SimpleSValuator : public SValuator {
	protected:
	virtual SVal EvalCastNL(NonLoc val, QualType castTy);
	virtual SVal EvalCastL(Loc val, QualType castTy);

	public:
	SimpleSValuator(ValueManager &valMgr) : SValuator(valMgr) {}
	virtual ~SimpleSValuator() {}

	virtual SVal EvalMinus(NonLoc val);
	virtual SVal EvalComplement(NonLoc val);
	virtual SVal EvalBinOpNN(const GRState *state, BinaryOperator::Opcode op,
	NonLoc lhs, NonLoc rhs, QualType resultTy);
	virtual SVal EvalBinOpLL(BinaryOperator::Opcode op, Loc lhs, Loc rhs,
	QualType resultTy);
	virtual SVal EvalBinOpLN(const GRState *state, BinaryOperator::Opcode op,
	Loc lhs, NonLoc rhs, QualType resultTy);
	};
	} // end anonymous namespace

	SValuator *clang::CreateSimpleSValuator(ValueManager &valMgr) {
	return new SimpleSValuator(valMgr);
	}

	//===----------------------------------------------------------------------===//
	// Transfer function for Casts.
	//===----------------------------------------------------------------------===//

	SVal SimpleSValuator::EvalCastNL(NonLoc val, QualType castTy) {

	bool isLocType = Loc::IsLocType(castTy);

	if (nonloc::LocAsInteger *LI = dyn_cast<nonloc::LocAsInteger>(&val)) {
	if (isLocType)
	return LI->getLoc();

	ASTContext &Ctx = ValMgr.getContext();

	// FIXME: Support promotions/truncations.
	if (Ctx.getTypeSize(castTy) == Ctx.getTypeSize(Ctx.VoidPtrTy))
	return val;

	return UnknownVal();
	}

	if (const SymExpr *se = val.getAsSymbolicExpression()) {
	ASTContext &Ctx = ValMgr.getContext();
	QualType T = Ctx.getCanonicalType(se->getType(Ctx));
	if (T == Ctx.getCanonicalType(castTy))
	return val;

	// FIXME: Remove this hack when we support symbolic truncation/extension.
	// HACK: If both castTy and T are integers, ignore the cast. This is
	// not a permanent solution. Eventually we want to precisely handle
	// extension/truncation of symbolic integers. This prevents us from losing
	// precision when we assign 'x = y' and 'y' is symbolic and x and y are
	// different integer types.
	if (T->isIntegerType() && castTy->isIntegerType())
	return val;

	return UnknownVal();
	}

	if (!isa<nonloc::ConcreteInt>(val))
	return UnknownVal();

	// Only handle casts from integers to integers.
	if (!isLocType && !castTy->isIntegerType())
	return UnknownVal();

	llvm::APSInt i = cast<nonloc::ConcreteInt>(val).getValue();
	i.setIsUnsigned(castTy->isUnsignedIntegerType() \|\| Loc::IsLocType(castTy));
	i.extOrTrunc(ValMgr.getContext().getTypeSize(castTy));

	if (isLocType)
	return ValMgr.makeIntLocVal(i);
	else
	return ValMgr.makeIntVal(i);
	}

	SVal SimpleSValuator::EvalCastL(Loc val, QualType castTy) {

	// Casts from pointers -> pointers, just return the lval.
	//
	// Casts from pointers -> references, just return the lval. These
	// can be introduced by the frontend for corner cases, e.g
	// casting from va_list* to __builtin_va_list&.
	//
	if (Loc::IsLocType(castTy) \|\| castTy->isReferenceType())
	return val;

	// FIXME: Handle transparent unions where a value can be "transparently"
	// lifted into a union type.
	if (castTy->isUnionType())
	return UnknownVal();

	assert(castTy->isIntegerType());
	unsigned BitWidth = ValMgr.getContext().getTypeSize(castTy);

	if (!isa<loc::ConcreteInt>(val))
	return ValMgr.makeLocAsInteger(val, BitWidth);

	llvm::APSInt i = cast<loc::ConcreteInt>(val).getValue();
	i.setIsUnsigned(castTy->isUnsignedIntegerType() \|\| Loc::IsLocType(castTy));
	i.extOrTrunc(BitWidth);
	return ValMgr.makeIntVal(i);
	}

	//===----------------------------------------------------------------------===//
	// Transfer function for unary operators.
	//===----------------------------------------------------------------------===//

	SVal SimpleSValuator::EvalMinus(NonLoc val) {
	switch (val.getSubKind()) {
	case nonloc::ConcreteIntKind:
	return cast<nonloc::ConcreteInt>(val).evalMinus(ValMgr);
	default:
	return UnknownVal();
	}
	}

	SVal SimpleSValuator::EvalComplement(NonLoc X) {
	switch (X.getSubKind()) {
	case nonloc::ConcreteIntKind:
	return cast<nonloc::ConcreteInt>(X).evalComplement(ValMgr);
	default:
	return UnknownVal();
	}
	}

	//===----------------------------------------------------------------------===//
	// Transfer function for binary operators.
	//===----------------------------------------------------------------------===//

	static BinaryOperator::Opcode NegateComparison(BinaryOperator::Opcode op) {
	switch (op) {
	default:
	assert(false && "Invalid opcode.");
	case BinaryOperator::LT: return BinaryOperator::GE;
	case BinaryOperator::GT: return BinaryOperator::LE;
	case BinaryOperator::LE: return BinaryOperator::GT;
	case BinaryOperator::GE: return BinaryOperator::LT;
	case BinaryOperator::EQ: return BinaryOperator::NE;
	case BinaryOperator::NE: return BinaryOperator::EQ;
	}
	}

	// Equality operators for Locs.
	// FIXME: All this logic will be revamped when we have MemRegion::getLocation()
	// implemented.

	static SVal EvalEquality(ValueManager &ValMgr, Loc lhs, Loc rhs, bool isEqual,
	QualType resultTy) {

	switch (lhs.getSubKind()) {
	default:
	assert(false && "EQ/NE not implemented for this Loc.");
	return UnknownVal();

	case loc::ConcreteIntKind: {
	if (SymbolRef rSym = rhs.getAsSymbol())
	return ValMgr.makeNonLoc(rSym,
	isEqual ? BinaryOperator::EQ
	: BinaryOperator::NE,
	cast<loc::ConcreteInt>(lhs).getValue(),
	resultTy);
	break;
	}
	case loc::MemRegionKind: {
	if (SymbolRef lSym = lhs.getAsLocSymbol()) {
	if (isa<loc::ConcreteInt>(rhs)) {
	return ValMgr.makeNonLoc(lSym,
	isEqual ? BinaryOperator::EQ
	: BinaryOperator::NE,
	cast<loc::ConcreteInt>(rhs).getValue(),
	resultTy);
	}
	}
	break;
	}

	case loc::GotoLabelKind:
	break;
	}

	return ValMgr.makeTruthVal(isEqual ? lhs == rhs : lhs != rhs, resultTy);
	}

	SVal SimpleSValuator::EvalBinOpNN(const GRState *state,
	BinaryOperator::Opcode op,
	NonLoc lhs, NonLoc rhs,
	QualType resultTy) {
	// Handle trivial case where left-side and right-side are the same.
	if (lhs == rhs)
	switch (op) {
	default:
	break;
	case BinaryOperator::EQ:
	case BinaryOperator::LE:
	case BinaryOperator::GE:
	return ValMgr.makeTruthVal(true, resultTy);
	case BinaryOperator::LT:
	case BinaryOperator::GT:
	case BinaryOperator::NE:
	return ValMgr.makeTruthVal(false, resultTy);
	}

	while (1) {
	switch (lhs.getSubKind()) {
	default:
	return UnknownVal();
	case nonloc::LocAsIntegerKind: {
	Loc lhsL = cast<nonloc::LocAsInteger>(lhs).getLoc();
	switch (rhs.getSubKind()) {
	case nonloc::LocAsIntegerKind:
	return EvalBinOpLL(op, lhsL, cast<nonloc::LocAsInteger>(rhs).getLoc(),
	resultTy);
	case nonloc::ConcreteIntKind: {
	// Transform the integer into a location and compare.
	ASTContext& Ctx = ValMgr.getContext();
	llvm::APSInt i = cast<nonloc::ConcreteInt>(rhs).getValue();
	i.setIsUnsigned(true);
	i.extOrTrunc(Ctx.getTypeSize(Ctx.VoidPtrTy));
	return EvalBinOpLL(op, lhsL, ValMgr.makeLoc(i), resultTy);
	}
	default:
	switch (op) {
	case BinaryOperator::EQ:
	return ValMgr.makeTruthVal(false, resultTy);
	case BinaryOperator::NE:
	return ValMgr.makeTruthVal(true, resultTy);
	default:
	// This case also handles pointer arithmetic.
	return UnknownVal();
	}
	}
	}
	case nonloc::SymExprValKind: {
	// Logical not?
	if (!(op == BinaryOperator::EQ && rhs.isZeroConstant()))
	return UnknownVal();

	const SymExpr *symExpr =
	cast<nonloc::SymExprVal>(lhs).getSymbolicExpression();

	// Only handle ($sym op constant) for now.
	if (const SymIntExpr *symIntExpr = dyn_cast<SymIntExpr>(symExpr)) {
	BinaryOperator::Opcode opc = symIntExpr->getOpcode();
	switch (opc) {
	case BinaryOperator::LAnd:
	case BinaryOperator::LOr:
	assert(false && "Logical operators handled by branching logic.");
	return UnknownVal();
	case BinaryOperator::Assign:
	case BinaryOperator::MulAssign:
	case BinaryOperator::DivAssign:
	case BinaryOperator::RemAssign:
	case BinaryOperator::AddAssign:
	case BinaryOperator::SubAssign:
	case BinaryOperator::ShlAssign:
	case BinaryOperator::ShrAssign:
	case BinaryOperator::AndAssign:
	case BinaryOperator::XorAssign:
	case BinaryOperator::OrAssign:
	case BinaryOperator::Comma:
	assert(false && "'=' and ',' operators handled by GRExprEngine.");
	return UnknownVal();
	case BinaryOperator::PtrMemD:
	case BinaryOperator::PtrMemI:
	assert(false && "Pointer arithmetic not handled here.");
	return UnknownVal();
	case BinaryOperator::Mul:
	case BinaryOperator::Div:
	case BinaryOperator::Rem:
	case BinaryOperator::Add:
	case BinaryOperator::Sub:
	case BinaryOperator::Shl:
	case BinaryOperator::Shr:
	case BinaryOperator::And:
	case BinaryOperator::Xor:
	case BinaryOperator::Or:
	// Not handled yet.
	return UnknownVal();
	case BinaryOperator::LT:
	case BinaryOperator::GT:
	case BinaryOperator::LE:
	case BinaryOperator::GE:
	case BinaryOperator::EQ:
	case BinaryOperator::NE:
	opc = NegateComparison(opc);
	assert(symIntExpr->getType(ValMgr.getContext()) == resultTy);
	return ValMgr.makeNonLoc(symIntExpr->getLHS(), opc,
	symIntExpr->getRHS(), resultTy);
	}
	}
	}
	case nonloc::ConcreteIntKind: {
	if (isa<nonloc::ConcreteInt>(rhs)) {
	const nonloc::ConcreteInt& lhsInt = cast<nonloc::ConcreteInt>(lhs);
	return lhsInt.evalBinOp(ValMgr, op, cast<nonloc::ConcreteInt>(rhs));
	}
	else {
	// Swap the left and right sides and flip the operator if doing so
	// allows us to better reason about the expression (this is a form
	// of expression canonicalization).
	NonLoc tmp = rhs;
	rhs = lhs;
	lhs = tmp;

	switch (op) {
	case BinaryOperator::LT: op = BinaryOperator::GT; continue;
	case BinaryOperator::GT: op = BinaryOperator::LT; continue;
	case BinaryOperator::LE: op = BinaryOperator::GE; continue;
	case BinaryOperator::GE: op = BinaryOperator::LE; continue;
	case BinaryOperator::EQ:
	case BinaryOperator::NE:
	case BinaryOperator::Add:
	case BinaryOperator::Mul:
	continue;
	default:
	return UnknownVal();
	}
	}
	}
	case nonloc::SymbolValKind: {
	nonloc::SymbolVal *slhs = cast<nonloc::SymbolVal>(&lhs);
	SymbolRef Sym = slhs->getSymbol();

	// Does the symbol simplify to a constant? If so, "fold" the constant
	// by setting 'lhs' to a ConcreteInt and try again.
	if (Sym->getType(ValMgr.getContext())->isIntegerType())
	if (const llvm::APSInt *Constant = state->getSymVal(Sym)) {
	// The symbol evaluates to a constant. If necessary, promote the
	// folded constant (LHS) to the result type.
	BasicValueFactory &BVF = ValMgr.getBasicValueFactory();
	const llvm::APSInt &lhs_I = BVF.Convert(resultTy, *Constant);
	lhs = nonloc::ConcreteInt(lhs_I);

	// Also promote the RHS (if necessary).

	// For shifts, it necessary promote the RHS to the result type.
	if (BinaryOperator::isShiftOp(op))
	continue;

	// Other operators: do an implicit conversion. This shouldn't be
	// necessary once we support truncation/extension of symbolic values.
	if (nonloc::ConcreteInt *rhs_I = dyn_cast<nonloc::ConcreteInt>(&rhs)){
	rhs = nonloc::ConcreteInt(BVF.Convert(resultTy, rhs_I->getValue()));
	}

	continue;
	}

	if (isa<nonloc::ConcreteInt>(rhs)) {
	return ValMgr.makeNonLoc(slhs->getSymbol(), op,
	cast<nonloc::ConcreteInt>(rhs).getValue(),
	resultTy);
	}

	return UnknownVal();
	}
	}
	}
	}

	SVal SimpleSValuator::EvalBinOpLL(BinaryOperator::Opcode op, Loc lhs, Loc rhs,
	QualType resultTy) {
	switch (op) {
	default:
	return UnknownVal();
	case BinaryOperator::EQ:
	case BinaryOperator::NE:
	return EvalEquality(ValMgr, lhs, rhs, op == BinaryOperator::EQ, resultTy);
	case BinaryOperator::LT:
	case BinaryOperator::GT:
	// FIXME: Generalize. For now, just handle the trivial case where
	// the two locations are identical.
	if (lhs == rhs)
	return ValMgr.makeTruthVal(false, resultTy);
	return UnknownVal();
	}
	}

	SVal SimpleSValuator::EvalBinOpLN(const GRState *state,
	BinaryOperator::Opcode op,
	Loc lhs, NonLoc rhs, QualType resultTy) {
	// Special case: 'rhs' is an integer that has the same width as a pointer and
	// we are using the integer location in a comparison. Normally this cannot be
	// triggered, but transfer functions like those for OSCommpareAndSwapBarrier32
	// can generate comparisons that trigger this code.
	// FIXME: Are all locations guaranteed to have pointer width?
	if (BinaryOperator::isEqualityOp(op)) {
	if (nonloc::ConcreteInt *rhsInt = dyn_cast<nonloc::ConcreteInt>(&rhs)) {
	const llvm::APSInt *x = &rhsInt->getValue();
	ASTContext &ctx = ValMgr.getContext();
	if (ctx.getTypeSize(ctx.VoidPtrTy) == x->getBitWidth()) {
	// Convert the signedness of the integer (if necessary).
	if (x->isSigned())
	x = &ValMgr.getBasicValueFactory().getValue(*x, true);

	return EvalBinOpLL(op, lhs, loc::ConcreteInt(*x), resultTy);
	}
	}
	}

	// Delegate pointer arithmetic to the StoreManager.
	return state->getStateManager().getStoreManager().EvalBinOp(state, op, lhs,
	rhs, resultTy);
	}