public SetDomain <T> Join(SetDomain <T> newState, out bool weaker, bool widen)
{
if (set == newState.set)
{
weaker = false; return(this);
}
if (this.IsBottom)
{
weaker = !newState.IsBottom; return(newState);
}
if (newState.IsBottom || this.IsTop)
{
weaker = false; return(this);
}
if (newState.IsTop)
{
weaker = !this.IsTop; return(newState);
}
Contract.Assert(set != null);
IFunctionalSet <T> result = set.Intersect(newState.set);
weaker = result.Count < set.Count;
return(new SetDomain <T>(result));
}
public bool LessEqual(SetDomain <T> that)
{
if (this.IsBottom)
{
return(true);
}
if (that.IsBottom)
{
return(false);
}
Contract.Assert(set != null);
return(that.set.Contained(set));
}
/// <summary>
/// Here we actually add constraints to our state.
/// </summary>
private Domain ConstrainLessThan(Expression var, Expression bound, Domain domain)
{
// First, skip unary coercions on var and bound
SkipConversionDecoder skipper = new SkipConversionDecoder();
var = this.context.Decode <Unit, Expression, SkipConversionDecoder>(var, skipper, Unit.Value);
bound = this.context.Decode <Unit, Expression, SkipConversionDecoder>(bound, skipper, Unit.Value);
Variable left = this.context.Unrefine(var);
Variable right = this.context.Unrefine(bound);
// add the bound to the set of bounds known
SetDomain <Variable> currentBounds =
(domain.Value.Contains(left)) ? domain.Value[left] : SetDomain <Variable> .TopValue;
return(new Domain(domain.Value.Add(left, currentBounds.Add(right))));
}
/// <summary>
/// Here's where the actual work is. We get passed a list of pairs (source,targets) representing
/// the assignments t = source for each t in targets.
///
/// For our domain, we thus add new mappings for all targets by looking up the bounds of the source and map the source bounds to new target bounds.
/// </summary>
public Domain ParallelAssign(Pair <Label, Label> edge, IFunctionalMap <Variable, FList <Variable> > sourceTargetMap, Domain state)
{
EnvironmentDomain <Variable, SetDomain <Variable> > originalState = state.Value;
EnvironmentDomain <Variable, SetDomain <Variable> > newState = originalState;
foreach (Variable source in sourceTargetMap.Keys)
{
FList <Variable> targets = sourceTargetMap[source];
// 1) for each target in this assignment, assign it the same bounds as source.
// 2) since we also have to map the source bounds, we assign it actually the union of all targets of all bounds of the source.
SetDomain <Variable> targetBounds = SetDomain <Variable> .TopValue;
if (originalState.Contains(source))
{
SetDomain <Variable> originalBounds = originalState[source];
foreach (Variable origBound in originalBounds.Elements)
{
FList <Variable> targetBoundNames = sourceTargetMap[origBound];
while (targetBoundNames != null)
{
targetBounds = targetBounds.Add(targetBoundNames.Head);
targetBoundNames = targetBoundNames.Tail;
}
}
}
if (targetBounds.IsTop)
{
// have no bounds, so havoc all targets
while (targets != null)
{
newState = newState.Remove(targets.Head);
targets = targets.Tail;
}
}
else
{
while (targets != null)
{
newState = newState.Add(targets.Head, targetBounds);
targets = targets.Tail;
}
}
}
return(new Domain(newState));
}
public SetDomain <T> Meet(SetDomain <T> that)
{
if (set == that.set)
{
return(this);
}
if (this.IsBottom || that.IsTop)
{
return(this);
}
if (that.IsBottom || this.IsTop)
{
return(that);
}
Contract.Assert(set != null);
IFunctionalSet <T> result = set.Union(that.set);
return(new SetDomain <T>(result));
}
/// <summary>
/// Here's one place where we want to check the bound. In principle, we want to only record the position and relevant
/// parameters for a proof obligation and check it only after the fixpoint is computed.
/// I'm lazy and checking it right away.
/// </summary>
public override Domain Ldelem(Label pc, Type type, Variable dest, Variable array, Variable index, Domain data)
{
if (data.Value.Contains(index))
{
SetDomain <Variable> bounds = data.Value[index];
// lookup upper bound of index and array bound
Variable bound;
if (this.context.TryGetArrayLength(pc, array, out bound))
{
if (Debug)
{
Console.WriteLine("bound for array {0} is {1}", array.ToString(), bound.ToString());
}
// check that bound is in bounds of index
if (!bounds.Contains(bound))
{
Console.WriteLine("{0}: WARNING: Can't prove that array index is okay", this.context.SourceContext(pc));
}
else
{
Console.WriteLine("{0}: INFO: Array index looks good.", this.context.SourceContext(pc));
}
}
else
{
Console.WriteLine("{0}: WARNING: Can't prove that array index is okay", this.context.SourceContext(pc));
}
}
else
{
Console.WriteLine("{0}: WARNING: Can't prove that array index is okay", this.context.SourceContext(pc));
}
// TODO: might want to constrain index by bound of array to eliminate subsequent errors
return(data);
}