internal static Statement GenerateForLoop(Variable loopVariable, Expression lowerBound, Expression upperBound, Statement body)
{
Block bodyAsBlock = body as Block ?? new Block(new StatementList(body));
Block init = new Block(new StatementList(2));
Block increment = new Block(new StatementList(1));
Block test = new Block(new StatementList(new Branch(
new BinaryExpression(loopVariable, upperBound, NodeType.Lt), bodyAsBlock))); //, false, true, false)));
init.Statements.Add(new AssignmentStatement(loopVariable, lowerBound));
init.Statements.Add(new Branch(null, test));
increment.Statements.Add(new AssignmentStatement(loopVariable, new BinaryExpression(loopVariable, Literal.Int32One, NodeType.Add)));
Block forLoop = new Block(new StatementList(4));
forLoop.Statements.Add(init);
forLoop.Statements.Add(bodyAsBlock);
forLoop.Statements.Add(increment);
forLoop.Statements.Add(test);
return forLoop;
}
public void SetToFalse(Variable v) {
this.egraph[v] = this.False;
}
public static string Name(Variable v)
{
Identifier name = v.Name;
string nstr = (name == null)?"":name.Name;
return String.Format("{0}({1})", nstr, v.UniqueKey);
}
protected override object VisitSizeOf(Variable dest, TypeNode value_type, Statement stat, object arg) {
ExposureState estate=(ExposureState)arg;
estate.AssignNonPointer(dest);
return arg;
}
protected override object VisitBinaryOperator(NodeType op, Variable dest, Variable operand1, Variable operand2, Statement stat, object arg) {
ExposureState estate=(ExposureState)arg;
// estate.AssignBinary(dest, op, operand1, operand2);
return arg;
}
protected override object VisitReturn(Variable var, Statement stat, object arg) {
ExposureState estate=(ExposureState)arg;
// TODO: see if returned value is supposed to be exposed or not and then what do we know about it?
return arg;
}
protected override object VisitLoadField(Variable dest, Variable source, Field field, Statement stat, object arg) {
ExposureState estate=(ExposureState)arg;
// Check the receiver here only if one needs to be unpacked for read access
//CheckReceiver(stat,source,estate);
return arg;
}
protected override object VisitCall(Variable dest, Variable receiver, Method callee, ExpressionList arguments, bool virtcall, Statement stat, object arg) {
ExposureState estate=(ExposureState)arg;
if (callee.CciKind == Cci.CciMemberKind.FrameGuardGetter){
// associate dest with receiver, because unpack is going to happen with dest as receiver
estate.AssignFrameFor(dest,receiver,callee.DeclaringType); // receiver could be a subtype of the type that the frame guard is for
}else if (callee == UnpackMethod){
if(estate.IsFrameExposable(receiver)) {
// BUGBUG: Using CopyVariable encodes the assumption that StartWritingTransitively returns itself!!! It may not!
estate.CopyVariable(receiver,dest);
estate.AssignFrameForExposed(dest);
}else{
TypeNode t = estate.LowerBoundOfObjectPointedToByFrame(receiver);
if (t == null){ // BUGBUG: is this the same as it being Top?
HandleError(stat, stat, Error.DontKnowIfCanExposeObject);
}else{
HandleError(stat, stat, Error.ExposingExposedObject);
}
return null;
}
}else if (callee == PackMethod){
estate.AssignFrameForNotExposed(receiver);
}else if (callee == IsExposableMethod){
estate.AssignFunctionLink(ExposureState.EqIsExposableId,dest,receiver);
}else if (callee == IsExposedMethod){
estate.AssignEqIsExposed(dest,receiver);
}else if (callee == AssertMethod){
Variable v = arguments[0] as Variable;
if (v != null && estate.IsFalse(v))
return null;
}
// Push possible exceptions to handlers.
for(int i=0;i<callee.Contract.Ensures.Count;i++){
EnsuresExceptional e=callee.Contract.Ensures[i] as EnsuresExceptional;
if(e!=null){
ExposureState newnn=new ExposureState(estate);
newnn.currentException=e.Type;
ExposureChecker.PushExceptionState(ExposureChecker.currBlock,newnn);
}
}
return arg;
}
public void AssignFrameForNotExposed(Variable guardVariable){
ISymValue guard = this.egraph[guardVariable];
ISymValue guardTypeObject = this.egraph[StaticTypeOf,guard];
Lattice.AVal guardsType = (Lattice.AVal)this.egraph[guardTypeObject];
ISymValue guardedObject = this.egraph[FrameFor, guard];
this.egraph[guardedObject] = guardsType;
}
public bool IsFrameExposable(Variable guardVariable){
ISymValue guard = this.egraph[guardVariable];
ISymValue guardedObject = this.egraph[FrameFor, guard];
ISymValue guardTypeObject = this.egraph[StaticTypeOf,guard];
Lattice.AVal guardsType = (Lattice.AVal)this.egraph[guardTypeObject];
Lattice.AVal guardedObjectsType = (Lattice.AVal)this.egraph[guardedObject];
return guardsType.lowerBound == guardedObjectsType.lowerBound;
}
public void AssignFrameForExposable(Variable guardVariable){
ISymValue guard = this.egraph[guardVariable];
this.AssignFrameForExposable(guard);
}
public void AssignFrameFor(Variable dest, Variable source, TypeNode t) {
ISymValue guard = this.egraph.FreshSymbol();
ISymValue guardedObject = this.egraph[source];
this.egraph[dest] = guard;
this.egraph[FrameFor, guard] = guardedObject;
ISymValue fresh = this.egraph.FreshSymbol();
this.egraph[fresh] = new Lattice.AVal(t,t);
this.egraph[StaticTypeOf, guard] = fresh;
}
public void CopyVariable(Variable source, Variable dest) {
this.egraph[dest] = this.egraph[source];
}
public void AssignNonPointer(Variable v) {
this.egraph.Eliminate(v);
}
public bool IsFalse(Variable v){
return this.egraph[v] == this.False;
}
protected override object VisitLoadConstant(Variable dest, Literal source, Statement stat, object arg)
{
ExposureState estate=(ExposureState)arg;
if (source == Literal.False){
estate.SetToFalse(dest);
}
return arg;
}
/// <summary>
/// Note: casts don't require a non-null argument. null value casts always succeed.
/// </summary>
protected override object VisitCastClass(Variable dest, TypeNode type, Variable source, Statement stat, object arg) {
ExposureState estate=(ExposureState)arg;
// acts like a copy retaining null status
estate.CopyVariable(source, dest);
return arg;
}
public void AssignEqIsExposed(Variable dest, Variable operand) {
ISymValue opval = this.egraph[operand];
ISymValue sv = this.egraph.FreshSymbol();
this.egraph[dest] = sv; // ?? Ask Manuel: Should it be the sv' that dest maps to that sv should be mapped to here?
this.egraph[EqIsExposedId, opval] = sv;
}
protected override object VisitConstrainedCall(Variable dest, Variable receiver, Method callee, ExpressionList arguments, TypeNode constraint, Statement stat, object arg) {
Reference rtype = receiver.Type as Reference;
if (rtype != null && rtype.ElementType != null && !rtype.ElementType.IsValueType) {
// instance could be a reference type that could be null.
// BUGBUG: when we track address of, we need to check here that target is indeed non-null
}
return VisitCall(dest, receiver, callee, arguments, true, stat, arg);
}
public void AssignFunctionLink(Identifier func, Variable dest, Variable operand) {
ISymValue opval = this.egraph[operand];
ISymValue sv = this.egraph.FreshSymbol();
this.egraph[dest] = sv; // ?? Ask Manuel: Should it be the sv' that dest maps to that sv should be mapped to here?
this.egraph[func, opval] = sv;
}
protected override object VisitStoreField(Variable dest, Field field, Variable source, Statement stat, object arg) {
ExposureState estate=(ExposureState)arg;
// static Fields
if(field.IsStatic){
}
// BUGBUG!!
// It seems that it would be better to start off ctors with the method's "this" object
// in the Exposed state, but I'm not sure how to do that.
This t = null;
ThisBinding tb = dest as ThisBinding;
if (tb != null){
t = tb.BoundThis;
}else{
t = dest as This;
}
if (t != null &&
this.ExposureChecker.currentMethod.NodeType == NodeType.InstanceInitializer
&& this.ExposureChecker.currentMethod.ThisParameter == t){
; // skip
}else{
ExposureState.Lattice.AVal valueOfdest = estate.GetAVal(dest);
if (valueOfdest.lowerBound == null || valueOfdest.upperBound == null){
HandleError(stat, stat, Error.WritingPackedObject, dest.Name.Name);
return arg;
}
if (valueOfdest.lowerBound.IsAssignableTo(field.DeclaringType)){
HandleError(stat, stat, Error.WritingPackedObject, dest.Name.Name);
return arg;
}
}
return arg;
}
public void RefineBranchInformation(Variable cond, out ExposureState trueState, out ExposureState falseState) {
ISymValue cv = this.egraph[cond];
trueState = new ExposureState(this);
falseState = new ExposureState(this);
AssumeTrue(cv, ref trueState);
AssumeFalse(cv, ref falseState);
}
protected override object VisitBranch(Variable cond, Block target, Statement stat, object arg) {
ExposureState estate=(ExposureState)arg;
if(cond==null)
return arg;
ExposureState trueState, falseState;
estate.RefineBranchInformation(cond, out trueState, out falseState);
if ( trueState != null ) {
ExposureChecker.PushState(ExposureChecker.currBlock, ExposureChecker.currBlock.TrueContinuation, trueState);
}
if ( falseState != null ) {
ExposureChecker.PushState(ExposureChecker.currBlock, ExposureChecker.currBlock.FalseContinuation, falseState);
}
return null;
}
/// <summary>
/// For the possible receiver v, check if it is nonnull. if no, file an proper
/// error/warning.
/// </summary>
private void CheckReceiver(Statement stat, Variable v, ExposureState estate)
{
Node offendingNode = v;
if (v == null) return;
if(estate.IsNotExposed(v))
{
HandleError(stat, offendingNode, Error.WritingPackedObject, v.Name.Name);
//estate.AssignExposed(v);
}
else if(!estate.IsExposed(v))
{
HandleError(stat, offendingNode, Error.WritingPackedObject, v.Name.Name);
//estate.AssumeNonNull(v);
}
}
protected override object VisitUnaryOperator(NodeType op, Variable dest, Variable operand, Statement stat, object arg) {
ExposureState estate=(ExposureState)arg;
return arg;
}
/// <summary>
/// Copy the source to dest.
///
/// If source is nonnull, no problem.
/// If source is null and dest is nonnulltype, Error
/// If source is possible null and dest is nonnulltype, warning.
/// Else, nothing.
///
/// Need to maintain proper heap transformation.
/// </summary>
/// <param name="dest"></param>
/// <param name="source"></param>
/// <param name="stat"></param>
/// <param name="arg"></param>
/// <returns></returns>
protected override object VisitCopy(Variable dest, Variable source, Statement stat, object arg) {
ExposureState estate=(ExposureState)arg;
estate.CopyVariable(source, dest);
return arg;
}
protected override object VisitBox(Variable dest, Variable source, TypeNode type, Statement stat, object arg) {
ExposureState estate=(ExposureState)arg;
return arg;
}
protected override object VisitLoadFunction(Variable dest, Variable source, Method method, Statement stat, object arg)
{
ExposureState estate=(ExposureState)arg;
if (method.IsVirtual)
{
// Check for Receiver non-nullness
CheckReceiver(stat,source,estate);
}
return arg;
}
protected override object VisitLoadNull(Variable dest, Literal source, Statement stat, object arg) {
ExposureState estate=(ExposureState)arg;
return arg;
}
public void AssignNotExposed(Variable v) {
AssignAVal(v, Lattice.AVal.IsNotExposed);
}