internal Dictionary <MethodDefinition, StateRange> finallyMethodToStateRange; // used only for IteratorDispose
/// <summary>
/// Initializes the state range logic:
/// Clears 'ranges' and sets 'ranges[entryPoint]' to the full range (int.MinValue to int.MaxValue)
/// </summary>
public StateRangeAnalysis(ILNode entryPoint, StateRangeAnalysisMode mode, FieldDefinition stateField, ILVariable cachedStateVar = null)
{
this.mode = mode;
this.stateField = stateField;
if (mode == StateRangeAnalysisMode.IteratorDispose)
{
finallyMethodToStateRange = new Dictionary <MethodDefinition, StateRange>();
}
ranges = new DefaultDictionary <ILNode, StateRange>(n => new StateRange());
ranges[entryPoint] = new StateRange(int.MinValue, int.MaxValue);
evalContext = new SymbolicEvaluationContext(stateField);
if (cachedStateVar != null)
{
evalContext.AddStateVariable(cachedStateVar);
}
}
public int AssignStateRanges(List <ILNode> body, int bodyLength)
{
if (bodyLength == 0)
{
return(0);
}
for (int i = 0; i < bodyLength; i++)
{
StateRange nodeRange = ranges[body[i]];
nodeRange.Simplify();
ILLabel label = body[i] as ILLabel;
if (label != null)
{
ranges[body[i + 1]].UnionWith(nodeRange);
continue;
}
ILTryCatchBlock tryFinally = body[i] as ILTryCatchBlock;
if (tryFinally != null)
{
if (mode == StateRangeAnalysisMode.IteratorDispose)
{
if (tryFinally.CatchBlocks.Count != 0 || tryFinally.FaultBlock != null || tryFinally.FinallyBlock == null)
{
throw new SymbolicAnalysisFailedException();
}
ranges[tryFinally.TryBlock].UnionWith(nodeRange);
if (tryFinally.TryBlock.Body.Count != 0)
{
ranges[tryFinally.TryBlock.Body[0]].UnionWith(nodeRange);
AssignStateRanges(tryFinally.TryBlock.Body, tryFinally.TryBlock.Body.Count);
}
continue;
}
else if (mode == StateRangeAnalysisMode.AsyncMoveNext)
{
return(i);
}
else
{
throw new SymbolicAnalysisFailedException();
}
}
ILExpression expr = body[i] as ILExpression;
if (expr == null)
{
throw new SymbolicAnalysisFailedException();
}
switch (expr.Code)
{
case ILCode.Switch:
{
SymbolicValue val = evalContext.Eval(expr.Arguments[0]);
if (val.Type != SymbolicValueType.State)
{
goto default;
}
ILLabel[] targetLabels = (ILLabel[])expr.Operand;
for (int j = 0; j < targetLabels.Length; j++)
{
int state = j - val.Constant;
ranges[targetLabels[j]].UnionWith(nodeRange, state, state);
}
StateRange nextRange = ranges[body[i + 1]];
nextRange.UnionWith(nodeRange, int.MinValue, -1 - val.Constant);
nextRange.UnionWith(nodeRange, targetLabels.Length - val.Constant, int.MaxValue);
break;
}
case ILCode.Br:
case ILCode.Leave:
ranges[(ILLabel)expr.Operand].UnionWith(nodeRange);
break;
case ILCode.Brtrue:
{
SymbolicValue val = evalContext.Eval(expr.Arguments[0]);
if (val.Type == SymbolicValueType.StateEquals)
{
ranges[(ILLabel)expr.Operand].UnionWith(nodeRange, val.Constant, val.Constant);
StateRange nextRange = ranges[body[i + 1]];
nextRange.UnionWith(nodeRange, int.MinValue, val.Constant - 1);
nextRange.UnionWith(nodeRange, val.Constant + 1, int.MaxValue);
break;
}
else if (val.Type == SymbolicValueType.StateInEquals)
{
ranges[body[i + 1]].UnionWith(nodeRange, val.Constant, val.Constant);
StateRange targetRange = ranges[(ILLabel)expr.Operand];
targetRange.UnionWith(nodeRange, int.MinValue, val.Constant - 1);
targetRange.UnionWith(nodeRange, val.Constant + 1, int.MaxValue);
break;
}
else
{
goto default;
}
}
case ILCode.Nop:
ranges[body[i + 1]].UnionWith(nodeRange);
break;
case ILCode.Ret:
break;
case ILCode.Stloc:
{
SymbolicValue val = evalContext.Eval(expr.Arguments[0]);
if (val.Type == SymbolicValueType.State && val.Constant == 0)
{
evalContext.AddStateVariable((ILVariable)expr.Operand);
goto case ILCode.Nop;
}
else
{
goto default;
}
}
case ILCode.Call:
// in some cases (e.g. foreach over array) the C# compiler produces a finally method outside of try-finally blocks
if (mode == StateRangeAnalysisMode.IteratorDispose)
{
MethodDefinition mdef = (expr.Operand as MethodReference).ResolveWithinSameModule();
if (mdef == null || finallyMethodToStateInterval.ContainsKey(mdef))
{
throw new SymbolicAnalysisFailedException();
}
finallyMethodToStateInterval.Add(mdef, nodeRange.ToEnclosingInterval());
break;
}
else
{
goto default;
}
default:
if (mode == StateRangeAnalysisMode.IteratorDispose)
{
throw new SymbolicAnalysisFailedException();
}
else
{
return(i);
}
}
}
return(bodyLength);
}