protected override IDataFlowState VisitStatement(CfgBlock block, Statement statement, IDataFlowState dfstate) {
// For debug purpose
try{
Analyzer.WriteLine(new SampleInstructionVisitor().Visit(statement,null)+" ::: " +statement.SourceContext.SourceText);
}catch(Exception){
Analyzer.WriteLine("Print error: "+statement);
}
IDataFlowState result=null;
try{
result =(IDataFlowState)(iVisitor.Visit(statement,dfstate));
}catch(ModifiesException e){
typeSystem.HandleError(statement,System.Compiler.Error.Warning,":"+e.Message);
}catch(Exception e){
typeSystem.HandleError(statement,System.Compiler.Error.Warning,":CFG1:"+e.Message);
}
Analyzer.WriteLine(dfstate);
return dfstate;
}
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;
}
protected override object VisitLoadNull(Variable dest, Literal source, Statement stat, object arg) {
ExposureState estate=(ExposureState)arg;
return arg;
}
private static bool IsNonTrivial(Statement s)
{
if (s == null) return false;
Block b = s as Block;
if (b != null) return (IsNonTrivial(b));
if (s.NodeType == NodeType.Nop) return false;
return true;
}
public static bool IsClosureCreation(Method containingMethod, Statement s, out Local closureLocal)
{
var closureType = IsClosureCreation(containingMethod, s);
if (closureType != null)
{
// it's a closure alright
var assign = s as AssignmentStatement;
if (assign != null)
{
closureLocal = assign.Target as Local;
}
else
{
closureLocal = null;
}
return true;
}
closureLocal = null;
return false;
}
/// <summary>
/// Perform subsitution if necessary (create fresh nodes)
/// </summary>
internal Statement Visit(Statement statement)
{
Contract.Requires(this.IsValid);
Contract.Requires(this.Depth >= 0);
Contract.Ensures(this.Depth >= -1);
if (statement == null) return null;
switch (statement.NodeType)
{
case NodeType.Nop:
case NodeType.Rethrow:
case NodeType.EndFilter:
case NodeType.EndFinally:
break;
case NodeType.Pop:
// a pop statement rather than expression
this.Depth--;
if (this.Depth < 0)
{
// we popped the original closure from the stack.
return null;
}
return statement;
case NodeType.AssignmentStatement:
var astmt = (AssignmentStatement) statement.Clone();
astmt.Target = Visit(astmt.Target);
astmt.Source = Visit(astmt.Source);
return astmt;
case NodeType.ExpressionStatement:
var estmt = (ExpressionStatement) statement.Clone();
if (estmt.Expression.NodeType == NodeType.Dup)
{
if (this.Depth == 0)
{
// duping the closure. Do nothing:
return null;
}
// otherwise, leave dup
}
else if (estmt.Expression.NodeType == NodeType.Pop)
{
var unary = estmt.Expression as UnaryExpression;
if (unary != null && unary.Operand != null)
{
// we are popping the thing we just push, so the depth does not change.
unary = (UnaryExpression) unary.Clone();
unary.Operand = Visit(unary.Operand);
estmt.Expression = unary;
return estmt;
}
// a pop statement rather than expression
this.Depth--;
if (this.Depth < 0)
{
// we popped the original closure from the stack.
return null;
}
}
else
{
estmt.Expression = Visit(estmt.Expression);
if (!IsVoidType(estmt.Expression.Type))
{
this.Depth++;
}
}
return estmt;
case NodeType.Block:
var block = (Block) statement.Clone();
block.Statements = Visit(block.Statements);
return block;
case NodeType.SwitchInstruction:
var sw = (SwitchInstruction) statement.Clone();
sw.Expression = Visit(sw.Expression);
return sw;
case NodeType.Throw:
var th = (Throw) statement.Clone();
th.Expression = Visit(th.Expression);
return th;
case NodeType.Return:
var ret = (Return) statement.Clone();
ret.Expression = Visit(ret.Expression);
return ret;
default:
var br = statement as Branch;
if (br != null)
{
br = (Branch) br.Clone();
br.Condition = Visit(br.Condition);
return br;
}
throw new NotImplementedException("ClosureNormalization Statement");
}
return statement;
}
/// <summary>
/// Checks whether a given CciHelper statement encodes an MSIL Pop instruction.
/// The correctness of this method depends heavily on what Herman does in the CciHelper reader ...
/// </summary>
/// <param name="stat">Statement to check.</param>
/// <returns><c>true</c> iff <c>stat</c> encodes an MSIL Pop instruction.</returns>
public static bool IsPopStatement(Statement stat)
{
if(stat.NodeType == NodeType.Pop)
return true;
ExpressionStatement expr_stat = stat as ExpressionStatement;
if(expr_stat == null) return false;
Expression expr = expr_stat.Expression;
if (expr.NodeType != NodeType.Pop) return false;
UnaryExpression unexpr = expr as UnaryExpression;
if ((unexpr != null ) && (unexpr.Operand != null) && (unexpr.Operand.NodeType != NodeType.Pop)) return false;
return true;
}
private static Statement WrapTryCatch(Method method, Statement statement)
{
Block afterCatches = new Block(new StatementList());
Block tryBlock = new Block(new StatementList());
Block blockAfterTryBody = new Block(null);
tryBlock.Statements.Add(statement);
tryBlock.Statements.Add(new Branch(null, afterCatches, false, true, true));
tryBlock.Statements.Add(blockAfterTryBody);
Block catchBlock = new Block(new StatementList());
// emit code that pops the exception and fools fxcop
Block branchTargetToFoolFxCop = new Block(null);
var branch = new Branch(new Expression(NodeType.Pop), branchTargetToFoolFxCop);
SourceContext hiddenContext = new SourceContext(HiddenDocument.Document);
branch.SourceContext = hiddenContext;
catchBlock.Statements.Add(branch);
var rethrowStatement = new Throw();
rethrowStatement.SourceContext = hiddenContext;
rethrowStatement.NodeType = NodeType.Rethrow;
catchBlock.Statements.Add(rethrowStatement);
catchBlock.Statements.Add(branchTargetToFoolFxCop);
var leave = new Branch(null, afterCatches, false, true, true);
leave.SourceContext = hiddenContext;
catchBlock.Statements.Add(leave);
Block tryCatch = new Block(new StatementList());
tryCatch.Statements.Add(tryBlock);
tryCatch.Statements.Add(catchBlock);
tryCatch.Statements.Add(afterCatches);
if (method.ExceptionHandlers == null) method.ExceptionHandlers = new ExceptionHandlerList();
ExceptionHandler exHandler = new ExceptionHandler();
exHandler.TryStartBlock = tryBlock;
exHandler.BlockAfterTryEnd = blockAfterTryBody;
exHandler.HandlerStartBlock = catchBlock;
exHandler.BlockAfterHandlerEnd = afterCatches;
exHandler.FilterType = SystemTypes.Exception;
exHandler.HandlerType = NodeType.Catch;
method.ExceptionHandlers.Add(exHandler);
return tryCatch;
}
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 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;
}
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 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);
}
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;
}
/// <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;
}
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>
/// Helper method for CCI decoding
/// </summary>
internal static Method ExtractCallFromStatement(Statement s)
{
MethodCall dummy;
return ExtractCallFromStatement(s, out dummy);
}
internal static Method ExtractCallFromStatement(Statement s, out MethodCall call)
{
call = null;
ExpressionStatement es = s as ExpressionStatement;
if (es == null) return null;
call = es.Expression as MethodCall;
if (call == null || call.Callee == null) { return null; }
MemberBinding mb = call.Callee as MemberBinding;
if (mb == null) { return null; }
Method m = mb.BoundMember as Method;
if (m == null) { return null; }
return m;
}
protected override object VisitNop(Statement stat, object arg) {
return arg;
}
public override void VisitReturn(Return Return)
{
this.ReturnStatement = Return;
base.VisitReturn(Return);
}
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>
/// Analyzes a statement to see if it is a call to a method.
/// </summary>
/// <param name="s">Any statement.</param>
/// <returns>The method m if the statement is an expression statement that is a method call to m or null</returns>
internal static Method IsMethodCall(Statement s)
{
if (s == null) return null;
ExpressionStatement es = s as ExpressionStatement;
if (es == null) return null;
// If the expression statement represents a method call, then it can
// have two different values as its expression:
// 0. if the method's return type is void, then the expression is just the
// method call.
// 1. if the method's return type is not void, then the value of the method
// isn't needed and it is wrapped inside of a unary expression,
// Pop(method call(...)) in order to throw away the return value
//
// We want the method call only if its return type is void, so just look
// for pattern 0.
//
MethodCall mc = es.Expression as MethodCall;
if (mc == null) return null;
MemberBinding mb = mc.Callee as MemberBinding;
if (mb == null) return null;
return mb.BoundMember as Method;
}
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;
}
private static bool IsDup(Statement statement)
{
var expr = statement as ExpressionStatement;
if (expr == null) return false;
if (expr.Expression != null && expr.Expression.NodeType == NodeType.Dup) return true;
return false;
}
protected override object VisitUnaryOperator(NodeType op, Variable dest, Variable operand, Statement stat, object arg) {
ExposureState estate=(ExposureState)arg;
return arg;
}
internal static TypeNode IsClosureCreation(Method containingMethod, Statement s)
{
AssignmentStatement assign = s as AssignmentStatement;
if (assign == null)
{
goto MaybePush;
}
Construct ctorCall = assign.Source as Construct;
if (ctorCall == null)
{
return null;
}
if (IsClosureType(containingMethod.DeclaringType, assign.Target.Type))
{
return assign.Target.Type;
}
MaybePush:
ExpressionStatement expr = s as ExpressionStatement;
if (expr == null)
{
return null;
}
var construct = expr.Expression as Construct;
if (construct == null) return null;
if (IsClosureType(containingMethod.DeclaringType, construct.Type))
{
return construct.Type;
}
return null;
}
protected override object VisitSizeOf(Variable dest, TypeNode value_type, Statement stat, object arg) {
ExposureState estate=(ExposureState)arg;
estate.AssignNonPointer(dest);
return arg;
}
internal void Visit(Statement statement)
{
Contract.Requires(this.IsValid);
if (statement == null) return;
switch (statement.NodeType)
{
case NodeType.Nop:
case NodeType.Rethrow:
case NodeType.EndFilter:
case NodeType.EndFinally:
break;
case NodeType.Pop:
// a pop statement rather than expression
return;
case NodeType.AssignmentStatement:
var astmt = (AssignmentStatement) statement;
Visit(astmt.Source);
var savedInStore = this.inStore;
try
{
this.inStore = true;
Visit(astmt.Target);
}
finally
{
this.inStore = savedInStore;
}
return;
case NodeType.ExpressionStatement:
var estmt = (ExpressionStatement) statement;
if (estmt.Expression.NodeType == NodeType.Dup)
{
return; // not an expression
}
if (estmt.Expression.NodeType == NodeType.Pop)
{
var unary = estmt.Expression as UnaryExpression;
if (unary != null && unary.Operand != null)
{
// we are popping the thing we just push, so the depth does not change.
Visit(unary.Operand);
return;
}
// a pop statement rather than expression
return;
}
Visit(estmt.Expression);
return;
case NodeType.Block:
var block = (Block) statement;
Visit(block.Statements);
return;
case NodeType.SwitchInstruction:
var sw = (SwitchInstruction) statement;
Visit(sw.Expression);
return;
case NodeType.Throw:
var th = (Throw) statement;
Visit(th.Expression);
return;
case NodeType.Return:
var ret = (Return) statement;
Visit(ret.Expression);
return;
default:
var br = statement as Branch;
if (br != null)
{
Visit(br.Condition);
return;
}
throw new NotImplementedException(string.Format("Expression scanner: {0}", statement.NodeType));
}
}
protected override object VisitBox(Variable dest, Variable source, TypeNode type, Statement stat, object arg) {
ExposureState estate=(ExposureState)arg;
return arg;
}
/// <summary>
/// Determines whether a statement is part of an anonymous delegate construction.
/// </summary>
/// <param name="statement">Statement to inspect.</param>
/// <returns><c>true</c> if <paramref name="statement"/> is part of anonymous delegate construction; otherwise, false.</returns>
internal static bool IsAnonymousDelegateConstruction(Statement statement)
{
AssignmentStatement assignment = statement as AssignmentStatement;
if (assignment != null)
{
if (assignment.Target != null &&
assignment.Target.Type != null &&
HelperMethods.IsCompilerGenerated(assignment.Target.Type))
{
return true;
}
MemberBinding binding = assignment.Target as MemberBinding;
if (binding != null)
{
if (binding.TargetObject != null &&
binding.TargetObject.Type != null &&
HelperMethods.IsCompilerGenerated(binding.TargetObject.Type))
{
return true;
}
if (HelperMethods.IsCompilerGenerated(binding.BoundMember)) return true;
}
Local local = assignment.Target as Local;
if (local != null &&
local.Name != null &&
local.Name.Name != null &&
local.Name.Name.StartsWith("<"))
{
return true;
}
}
return false;
}
private static bool IsChainConstructorCall(Statement statement)
{
var expression = statement as ExpressionStatement;
if (expression == null) return false;
var method = expression.Expression as MethodCall;
if (method == null) return false;
var callee = method.Callee as MemberBinding;
if (callee == null) return false;
return callee.BoundMember is InstanceInitializer;
}
