public BigLiteralAbstracter(VCExpressionGenerator gen)
: base(gen)
{
Contract.Requires(gen != null);
DummyVar = gen.Variable("x", Type.Int);
IncAxioms = new List <VCExpr>();
Literals = new List <KeyValuePair <BigNum, VCExprVar> >();
}
private VCExpr create_let(Term t, VCExpr u)
{
var name = "$x" + let_ctr.ToString();
let_ctr++;
var sym = gen.Variable(name, u.Type);
memo.Remove(t);
memo.Add(t, sym);
lets.Add(gen.LetBinding(sym, u));
return(sym);
}
////////////////////////////////////////////////////////////////////////////
private VCExprVar AbstractWithVariable(VCExpr s, VCExpr t)
{
Contract.Requires(t != null);
Contract.Requires(s != null);
Contract.Requires((s.Type.Equals(t.Type)));
Contract.Ensures(Contract.Result<VCExprVar>() != null);
ExprPair pair = new ExprPair(s, t);
if (!Representation.TryGetValue(pair, out var repr))
{
repr = Gen.Variable("abs" + Representation.Count, s.Type);
Representation.Add(pair, repr);
}
return cce.NonNull(repr);
}
/// <summary>
/// Computes the wlp for an assert or assume command "cmd".
/// </summary>
internal static VCExpr Cmd(Block b, Cmd cmd, VCExpr N, VCContext ctxt)
{
Contract.Requires(cmd != null);
Contract.Requires(N != null);
Contract.Requires(ctxt != null);
Contract.Ensures(Contract.Result <VCExpr>() != null);
VCExpressionGenerator gen = ctxt.Ctxt.ExprGen;
Contract.Assert(gen != null);
if (cmd is AssertCmd)
{
AssertCmd ac = (AssertCmd)cmd;
var isFullyVerified = false;
if (ac.VerifiedUnder != null)
{
var litExpr = ac.VerifiedUnder as LiteralExpr;
isFullyVerified = litExpr != null && litExpr.IsTrue;
}
if (!isFullyVerified)
{
ctxt.Ctxt.BoogieExprTranslator.isPositiveContext = !ctxt.Ctxt.BoogieExprTranslator.isPositiveContext;
}
VCExpr C = ctxt.Ctxt.BoogieExprTranslator.Translate(ac.Expr);
VCExpr VU = null;
if (!isFullyVerified)
{
if (ac.VerifiedUnder != null)
{
VU = ctxt.Ctxt.BoogieExprTranslator.Translate(ac.VerifiedUnder);
if (CommandLineOptions.Clo.RunDiagnosticsOnTimeout)
{
ctxt.Ctxt.TimeoutDiagnosticIDToAssertion[ctxt.Ctxt.TimeoutDiagnosticsCount] =
new Tuple <AssertCmd, TransferCmd>(ac, b.TransferCmd);
VU = gen.Or(VU,
gen.Function(VCExpressionGenerator.TimeoutDiagnosticsOp,
gen.Integer(BigNum.FromInt(ctxt.Ctxt.TimeoutDiagnosticsCount++))));
}
}
else if (CommandLineOptions.Clo.RunDiagnosticsOnTimeout)
{
ctxt.Ctxt.TimeoutDiagnosticIDToAssertion[ctxt.Ctxt.TimeoutDiagnosticsCount] =
new Tuple <AssertCmd, TransferCmd>(ac, b.TransferCmd);
VU = gen.Function(VCExpressionGenerator.TimeoutDiagnosticsOp,
gen.Integer(BigNum.FromInt(ctxt.Ctxt.TimeoutDiagnosticsCount++)));
}
ctxt.Ctxt.BoogieExprTranslator.isPositiveContext = !ctxt.Ctxt.BoogieExprTranslator.isPositiveContext;
}
{
var subsumption = Subsumption(ac);
if (subsumption == CommandLineOptions.SubsumptionOption.Always ||
(subsumption == CommandLineOptions.SubsumptionOption.NotForQuantifiers && !(C is VCExprQuantifier)))
{
N = gen.ImpliesSimp(C, N, false);
}
if (isFullyVerified)
{
return(N);
}
else if (VU != null)
{
C = gen.OrSimp(VU, C);
}
int id = ac.UniqueId;
if (ctxt.Label2absy != null)
{
ctxt.Label2absy[id] = ac;
}
ctxt.AssertionCount++;
if (ctxt.ControlFlowVariableExpr == null)
{
Contract.Assert(ctxt.Label2absy != null);
return(gen.AndSimp(C, N));
}
else
{
VCExpr controlFlowFunctionAppl = gen.ControlFlowFunctionApplication(ctxt.ControlFlowVariableExpr,
gen.Integer(BigNum.FromInt(b.UniqueId)));
Contract.Assert(controlFlowFunctionAppl != null);
VCExpr assertFailure = gen.Eq(controlFlowFunctionAppl, gen.Integer(BigNum.FromInt(-ac.UniqueId)));
return(gen.AndSimp(gen.Implies(assertFailure, C), N));
}
}
}
else if (cmd is AssumeCmd)
{
AssumeCmd ac = (AssumeCmd)cmd;
if (CommandLineOptions.Clo.StratifiedInlining > 0)
{
// Label the assume if it is a procedure call
NAryExpr naryExpr = ac.Expr as NAryExpr;
if (naryExpr != null)
{
if (naryExpr.Fun is FunctionCall)
{
int id = ac.UniqueId;
ctxt.Label2absy[id] = ac;
return(MaybeWrapWithOptimization(ctxt, gen, ac.Attributes,
gen.ImpliesSimp(ctxt.Ctxt.BoogieExprTranslator.Translate(ac.Expr), N)));
}
}
}
var expr = ctxt.Ctxt.BoogieExprTranslator.Translate(ac.Expr);
var aid = QKeyValue.FindStringAttribute(ac.Attributes, "id");
if (aid != null)
{
var isTry = QKeyValue.FindBoolAttribute(ac.Attributes, "try");
var v = gen.Variable((isTry ? "try$$" : "assume$$") + aid, Microsoft.Boogie.Type.Bool);
expr = gen.Function(VCExpressionGenerator.NamedAssumeOp, v, gen.ImpliesSimp(v, expr));
}
var soft = QKeyValue.FindBoolAttribute(ac.Attributes, "soft");
var softWeight = QKeyValue.FindIntAttribute(ac.Attributes, "soft", 0);
if ((soft || 0 < softWeight) && aid != null)
{
var v = gen.Variable("soft$$" + aid, Microsoft.Boogie.Type.Bool);
expr = gen.Function(new VCExprSoftOp(Math.Max(softWeight, 1)), v, gen.ImpliesSimp(v, expr));
}
return(MaybeWrapWithOptimization(ctxt, gen, ac.Attributes, gen.ImpliesSimp(expr, N)));
}
else
{
Console.WriteLine(cmd.ToString());
Contract.Assert(false);
throw new cce.UnreachableException(); // unexpected command
}
}
public void GenerateVCBoolControl()
{
Debug.Assert(!initialized);
Debug.Assert(CommandLineOptions.Clo.SIBoolControlVC);
// fix names for exit variables
var outputVariables = new List<Variable>();
var assertConjuncts = new List<Expr>();
foreach (Variable v in impl.OutParams)
{
Constant c = new Constant(Token.NoToken,
new TypedIdent(Token.NoToken, impl.Name + "_" + v.Name, v.TypedIdent.Type));
outputVariables.Add(c);
Expr eqExpr = Expr.Eq(new IdentifierExpr(Token.NoToken, c), new IdentifierExpr(Token.NoToken, v));
assertConjuncts.Add(eqExpr);
}
foreach (IdentifierExpr e in impl.Proc.Modifies)
{
if (e.Decl == null) continue;
Variable v = e.Decl;
Constant c = new Constant(Token.NoToken,
new TypedIdent(Token.NoToken, impl.Name + "_" + v.Name, v.TypedIdent.Type));
outputVariables.Add(c);
Expr eqExpr = Expr.Eq(new IdentifierExpr(Token.NoToken, c), new IdentifierExpr(Token.NoToken, v));
assertConjuncts.Add(eqExpr);
}
exitAssertCmd = new AssumeCmd(Token.NoToken, Expr.BinaryTreeAnd(assertConjuncts));
(exitAssertCmd as AssumeCmd).Attributes = new QKeyValue(Token.NoToken, "exitAssert", new List<object>(), null);
// no need for label2absy
label2absy = new Dictionary<int, Absy>();
// Passify
Program program = vcgen.program;
ProverInterface proverInterface = vcgen.prover;
vcgen.ConvertCFG2DAG(impl);
vcgen.PassifyImpl(impl, out mvInfo);
VCExpressionGenerator gen = proverInterface.VCExprGen;
var exprGen = proverInterface.Context.ExprGen;
var translator = proverInterface.Context.BoogieExprTranslator;
// add a boolean variable at each call site
vcgen.InstrumentCallSites(impl);
// typecheck
var tc = new TypecheckingContext(null);
impl.Typecheck(tc);
///////////////////
// Generate the VC
///////////////////
// block -> bool variable
blockToControlVar = new Dictionary<Block, VCExprVar>();
foreach (var b in impl.Blocks)
blockToControlVar.Add(b, gen.Variable(b.Label + "_holds", Bpl.Type.Bool));
vcexpr = VCExpressionGenerator.True;
foreach (var b in impl.Blocks)
{
// conjoin all assume cmds
VCExpr c = VCExpressionGenerator.True;
foreach (var cmd in b.Cmds)
{
var acmd = cmd as AssumeCmd;
if (acmd == null)
{
Debug.Assert(cmd is AssertCmd && (cmd as AssertCmd).Expr is LiteralExpr &&
((cmd as AssertCmd).Expr as LiteralExpr).IsTrue);
continue;
}
var expr = translator.Translate(acmd.Expr);
c = gen.AndSimp(c, expr);
}
// block implies a disjunction of successors
Debug.Assert(!(b.TransferCmd is ReturnExprCmd), "Not supported");
var gc = b.TransferCmd as GotoCmd;
if (gc != null)
{
VCExpr succ = VCExpressionGenerator.False;
foreach (var sb in gc.labelTargets)
succ = gen.OrSimp(succ, blockToControlVar[sb]);
c = gen.AndSimp(c, succ);
}
else
{
// nothing to do
}
vcexpr = gen.AndSimp(vcexpr, gen.Eq(blockToControlVar[b], c));
}
// assert start block
vcexpr = gen.AndSimp(vcexpr, blockToControlVar[impl.Blocks[0]]);
//Console.WriteLine("VC of {0}: {1}", impl.Name, vcexpr);
// Collect other information
callSites = vcgen.CollectCallSites(impl);
recordProcCallSites = vcgen.CollectRecordProcedureCallSites(impl);
// record interface variables
privateExprVars = new List<VCExprVar>();
foreach (Variable v in impl.LocVars)
{
privateExprVars.Add(translator.LookupVariable(v));
}
foreach (Variable v in impl.OutParams)
{
privateExprVars.Add(translator.LookupVariable(v));
}
privateExprVars.AddRange(blockToControlVar.Values);
interfaceExprVars = new List<VCExprVar>();
foreach (Variable v in program.GlobalVariables)
{
interfaceExprVars.Add(translator.LookupVariable(v));
}
foreach (Variable v in impl.InParams)
{
interfaceExprVars.Add(translator.LookupVariable(v));
}
foreach (Variable v in outputVariables)
{
interfaceExprVars.Add(translator.LookupVariable(v));
}
}
VCExpr LetVC(Block block,
Dictionary <int, Absy> label2absy,
Hashtable /*<Block, VCExprVar!>*/ blockVariables,
List <VCExprLetBinding> bindings,
ProverContext proverCtxt,
out int assertionCount)
{
Contract.Requires(label2absy != null);
Contract.Requires(blockVariables != null);
Contract.Requires(proverCtxt != null);
Contract.Requires(cce.NonNullElements(bindings));
Contract.Ensures(Contract.Result <VCExpr>() != null);
assertionCount = 0;
VCExpressionGenerator gen = proverCtxt.ExprGen;
Contract.Assert(gen != null);
VCExprVar v = (VCExprVar)blockVariables[block];
if (v == null)
{
/*
* For block A (= block), generate:
* LET_binding A_correct = wp(A_body, (/\ S \in Successors(A) :: S_correct))
* with the side effect of adding the let bindings to "bindings" for any
* successor not yet visited.
*/
VCExpr SuccCorrect;
GotoCmd gotocmd = block.TransferCmd as GotoCmd;
if (gotocmd == null)
{
if (CommandLineOptions.Clo.vcVariety == CommandLineOptions.VCVariety.Doomed)
{
SuccCorrect = VCExpressionGenerator.False;
}
else
{
SuccCorrect = VCExpressionGenerator.True;
}
}
else
{
Contract.Assert(gotocmd.labelTargets != null);
List <VCExpr> SuccCorrectVars = new List <VCExpr>(gotocmd.labelTargets.Count);
foreach (Block successor in gotocmd.labelTargets)
{
Contract.Assert(successor != null);
int ac;
VCExpr s = LetVC(successor, label2absy, blockVariables, bindings, proverCtxt, out ac);
assertionCount += ac;
SuccCorrectVars.Add(s);
}
SuccCorrect = gen.NAry(VCExpressionGenerator.AndOp, SuccCorrectVars);
}
VCContext context = new VCContext(label2absy, proverCtxt);
// m_Context = context;
VCExpr vc = Wlp.Block(block, SuccCorrect, context);
assertionCount += context.AssertionCount;
v = gen.Variable(block.Label + "_correct", Microsoft.Boogie.Type.Bool);
bindings.Add(gen.LetBinding(v, vc));
blockVariables.Add(block, v);
}
return(v);
}
