private static void AnalyzeDependencyWithUnsatCore(VCExpr programVC, Constant outConstant, Dependencies result, string procName, List <Constant> inputGuardConsts, List <Constant> outputGuardConsts)
{
#region Description of UNSAT core logic implemented below
/*
* Given VC, I, O, o
* - preInp = (\wedge_{i \in I} i)
* - preOut = (\wedge_{o' \in O} !o') \wedge o
* - VC' = (preOut => VC)
* - checkValid preInp => VC'
* - if invalid return
* - A += !VC'
* - A += I
* - if (CheckAssumption(A, out core) != valid) ABORT
*/
#endregion
//Should call VerifyVC before invoking CheckAssumptions
List <Counterexample> cexs;
var preInp = inputGuardConsts
.Aggregate(VCExpressionGenerator.True, (x, y) => VC.exprGen.And(x, VC.translator.LookupVariable(y)));
var preOut = outputGuardConsts
.Where(x => x != outConstant)
.Aggregate(VCExpressionGenerator.True, (x, y) => VC.exprGen.And(x, VC.exprGen.Not(VC.translator.LookupVariable(y))));
preOut = VC.exprGen.And(preOut, VC.translator.LookupVariable(outConstant));
var newVC = VC.exprGen.Implies(preOut, programVC);
//TODO: Really really ugly way to get to the Variable in the guardOutput
var vexpr = (Expr)Utils.AttributeUtils.GetAttributeVals(outConstant.Attributes, RefineConsts.modSetGuradAttribute)[1];
var vident = vexpr as IdentifierExpr;
if (vident == null)
{
throw new Exception(string.Format("Illegal variable expression {0} in {1} attribute", vexpr, RefineConsts.modSetGuardName));
}
var v = vident.Decl;
//check for validity (presence of all input eq implies output is equal)
var outcome = VC.VerifyVC("RefineDependency", VC.exprGen.Implies(preInp, newVC), out cexs);
Console.Write("-");
if (outcome == ProverInterface.Outcome.Invalid)
{
Console.WriteLine("\t VC not valid, returning");
result[v].Add(Utils.VariableUtils.NonDetVar);
Console.WriteLine("\t Dependency of {0} = <{1}>", v, string.Join(",", result[v]));
return;
}
if (outcome == ProverInterface.Outcome.OutOfMemory ||
outcome == ProverInterface.Outcome.TimeOut ||
outcome == ProverInterface.Outcome.Undetermined)
{
Console.WriteLine("\t VC inconclusive, returning");
result[v].Add(Utils.VariableUtils.NonDetVar);
Console.WriteLine("\t Dependency of {0} = <{1}>", v, string.Join(",", result[v]));
return;
}
List <int> unsatClauseIdentifiers = new List <int>();
var assumptions = new List <VCExpr>();
assumptions.Add(VC.exprGen.Not(newVC));
//Add the list of all input constants
inputGuardConsts.ForEach(x => assumptions.Add(VC.translator.LookupVariable(x)));
//VERY IMPORTANT: TO USE UNSAT CORE, SET ContractInfer to true in CommandLineOptions.Clo.
outcome = ProverInterface.Outcome.Undetermined;
outcome = VC.proverInterface.CheckAssumptions(assumptions, out unsatClauseIdentifiers, VC.handler);
Console.Write("+");
if (outcome == ProverInterface.Outcome.Invalid && unsatClauseIdentifiers.Count() == 0)
{
Console.WriteLine("Something went wrong! Unsat core with 0 elements for {0}", outConstant);
return;
}
if (!unsatClauseIdentifiers.Remove(0)) //newVC should be always at 0, since it has to participate in inconsistency
{
Console.WriteLine("Something went wrong! The VC itself is not part of UNSAT core");
return;
}
//Core may not be minimal (e.g. testdependencyDummy.bpl), need to iterate
var core0 = unsatClauseIdentifiers.Select(i => assumptions[i]);
var core = new List <VCExpr>(core0);
if (!Analysis.noMinUnsatCore)
{
core0
.Iter(b =>
{
core.Remove(b);
preInp = core.Aggregate(VCExpressionGenerator.True, (x, y) => VC.exprGen.And(x, y));
outcome = VC.VerifyVC("RefineDependency", VC.exprGen.Implies(preInp, newVC), out cexs);
Console.Write(".");
if (outcome != ProverInterface.Outcome.Valid)
{
core.Add(b);
return;
}
});
}
//We are about to refine the dependency of v, so we start with the empty set
result[v] = new VarSet();
//TODO: THIS HAS TO GO AWAY with proper variables!!!
foreach (var ig in inputGuardConsts)
{
if (core.Contains(VC.translator.LookupVariable(ig)))
{
IdentifierExpr iexpr = (IdentifierExpr)Utils.AttributeUtils.GetAttributeVals(ig.Attributes, RefineConsts.readSetGuradAttribute)[1];
result[v].Add(iexpr.Decl);
}
}
Console.WriteLine("\t Dependency of {0} = <{1}>",
v,
string.Join(",", result[v]));
}
