public static Expr Extract(Expr expr, Program program, List <Axiom> axioms)
{
Contract.Requires(expr != null && program != null && !program.TopLevelDeclarationsAreFrozen && axioms != null);
if (expr is LiteralExpr)
{
return(expr);
}
var extractor = new FunctionExtractor();
var body = extractor.VisitExpr(expr);
var name = program.FreshExtractedFunctionName();
var originalVars = extractor.Substitutions.Keys.ToList();
var formalInArgs = originalVars.Select(v => new Formal(Token.NoToken, new TypedIdent(Token.NoToken, extractor.Substitutions[v].Name, extractor.Substitutions[v].TypedIdent.Type), true)).ToList <Variable>();
var formalOutArg = new Formal(Token.NoToken, new TypedIdent(Token.NoToken, name + "$result$", expr.Type), false);
var func = new Function(Token.NoToken, name, formalInArgs, formalOutArg);
func.AddAttribute("never_pattern");
var boundVars = originalVars.Select(k => extractor.Substitutions[k]);
var axiomCall = new NAryExpr(Token.NoToken, new FunctionCall(func), boundVars.Select(b => new IdentifierExpr(Token.NoToken, b)).ToList <Expr>());
axiomCall.Type = expr.Type;
axiomCall.TypeParameters = SimpleTypeParamInstantiation.EMPTY;
var eq = LiteralExpr.Eq(axiomCall, body);
eq.Type = body.Type;
eq.TypeParameters = SimpleTypeParamInstantiation.EMPTY;
if (0 < formalInArgs.Count)
{
var forallExpr = new ForallExpr(Token.NoToken, boundVars.ToList <Variable>(), new Trigger(Token.NoToken, true, new List <Expr> {
axiomCall
}), eq);
body = forallExpr;
forallExpr.Attributes = new QKeyValue(Token.NoToken, "weight", new List <object> {
new LiteralExpr(Token.NoToken, Basetypes.BigNum.FromInt(30))
}, null);
body.Type = Type.Bool;
}
else
{
body = eq;
}
var axiom = new Axiom(Token.NoToken, body);
func.DefinitionAxiom = axiom;
program.AddTopLevelDeclaration(func);
program.AddTopLevelDeclaration(axiom);
axioms.Add(axiom);
var call = new NAryExpr(Token.NoToken, new FunctionCall(func), originalVars.Select(v => new IdentifierExpr(Token.NoToken, v)).ToList <Expr>());
call.Type = expr.Type;
call.TypeParameters = SimpleTypeParamInstantiation.EMPTY;
return(call);
}
public override Cmd VisitCallCmd(CallCmd node)
{
var result = base.VisitCallCmd(node);
var oldProc = programInCachedSnapshot.FindProcedure(node.Proc.Name);
if (oldProc != null &&
oldProc.DependencyChecksum != node.Proc.DependencyChecksum &&
node.AssignedAssumptionVariable == null)
{
var before = new List <Cmd>();
var beforePreconditionCheck = new List <Cmd>();
var after = new List <Cmd>();
var axioms = new List <Axiom>();
Expr assumedExpr = new LiteralExpr(Token.NoToken, false);
// TODO(wuestholz): Try out two alternatives: only do this for low priority implementations or not at all.
var canUseSpecs = DependencyCollector.CanExpressOldSpecs(oldProc, Program);
if (canUseSpecs && oldProc.SignatureEquals(node.Proc))
{
var desugaring = node.Desugaring;
Contract.Assert(desugaring != null);
var precond = node.CheckedPrecondition(oldProc, Program, e => FunctionExtractor.Extract(e, Program, axioms));
if (precond != null)
{
var assume = new AssumeCmd(node.tok, precond,
new QKeyValue(Token.NoToken, "precondition_previous_snapshot", new List <object>(), null));
assume.IrrelevantForChecksumComputation = true;
beforePreconditionCheck.Add(assume);
}
var unmods = node.UnmodifiedBefore(oldProc);
var eqs = new List <Expr>();
foreach (var unmod in unmods)
{
var oldUnmod = new LocalVariable(Token.NoToken,
new TypedIdent(Token.NoToken, string.Format("{0}##old##{1}", unmod.Name, FreshTemporaryVariableName),
unmod.Type));
var lhs = new SimpleAssignLhs(Token.NoToken, new IdentifierExpr(Token.NoToken, oldUnmod));
var rhs = new IdentifierExpr(Token.NoToken, unmod.Decl);
var cmd = new AssignCmd(Token.NoToken, new List <AssignLhs> {
lhs
}, new List <Expr> {
rhs
});
cmd.IrrelevantForChecksumComputation = true;
before.Add(cmd);
var eq = LiteralExpr.Eq(new IdentifierExpr(Token.NoToken, oldUnmod),
new IdentifierExpr(Token.NoToken, unmod.Decl));
eq.Type = Type.Bool;
eq.TypeParameters = SimpleTypeParamInstantiation.EMPTY;
eqs.Add(eq);
}
var mods = node.ModifiedBefore(oldProc);
var oldSubst = new Dictionary <Variable, Expr>();
foreach (var mod in mods)
{
var oldMod = new LocalVariable(Token.NoToken,
new TypedIdent(Token.NoToken, string.Format("{0}##old##{1}", mod.Name, FreshTemporaryVariableName),
mod.Type));
oldSubst[mod.Decl] = new IdentifierExpr(Token.NoToken, oldMod);
var lhs = new SimpleAssignLhs(Token.NoToken, new IdentifierExpr(Token.NoToken, oldMod));
var rhs = new IdentifierExpr(Token.NoToken, mod.Decl);
var cmd = new AssignCmd(Token.NoToken, new List <AssignLhs> {
lhs
}, new List <Expr> {
rhs
});
cmd.IrrelevantForChecksumComputation = true;
before.Add(cmd);
}
assumedExpr = node.Postcondition(oldProc, eqs, oldSubst, Program,
e => FunctionExtractor.Extract(e, Program, axioms));
if (assumedExpr == null)
{
assumedExpr = new LiteralExpr(Token.NoToken, true);
}
}
if (assumedExpr != null)
{
var lv = new LocalVariable(Token.NoToken,
new TypedIdent(Token.NoToken, string.Format("a##cached##{0}", FreshAssumptionVariableName), Type.Bool),
new QKeyValue(Token.NoToken, "assumption", new List <object>(), null));
node.AssignedAssumptionVariable = lv;
currentImplementation.InjectAssumptionVariable(lv, !canUseSpecs);
var lhs = new SimpleAssignLhs(Token.NoToken, new IdentifierExpr(Token.NoToken, lv));
var rhs = LiteralExpr.And(new IdentifierExpr(Token.NoToken, lv), assumedExpr);
var assumed = new AssignCmd(node.tok, new List <AssignLhs> {
lhs
}, new List <Expr> {
rhs
});
assumed.IrrelevantForChecksumComputation = true;
after.Add(assumed);
}
node.ExtendDesugaring(before, beforePreconditionCheck, after);
if (CommandLineOptions.Clo.TraceCachingForTesting || CommandLineOptions.Clo.TraceCachingForBenchmarking)
{
using (var tokTxtWr = new TokenTextWriter("<console>", Console.Out, false, false))
{
var loc = node.tok != null && node.tok != Token.NoToken
? string.Format("{0}({1},{2})", node.tok.filename, node.tok.line, node.tok.col)
: "<unknown location>";
Console.Out.WriteLine("Processing call to procedure {0} in implementation {1} (at {2}):", node.Proc.Name,
currentImplementation.Name, loc);
foreach (var a in axioms)
{
Console.Out.Write(" >>> added axiom: ");
a.Expr.Emit(tokTxtWr);
Console.Out.WriteLine();
}
foreach (var b in before)
{
Console.Out.Write(" >>> added before: ");
b.Emit(tokTxtWr, 0);
}
foreach (var b in beforePreconditionCheck)
{
Console.Out.Write(" >>> added before precondition check: ");
b.Emit(tokTxtWr, 0);
}
foreach (var a in after)
{
Console.Out.Write(" >>> added after: ");
a.Emit(tokTxtWr, 0);
}
}
}
}
return(result);
}
public Implementation Inject(Implementation implementation, Program programInCachedSnapshot)
{
Contract.Requires(implementation != null && programInCachedSnapshot != null);
this.programInCachedSnapshot = programInCachedSnapshot;
assumptionVariableCount = 0;
temporaryVariableCount = 0;
currentImplementation = implementation;
#region Introduce explict assumption about the precondition.
var oldProc = programInCachedSnapshot.FindProcedure(currentImplementation.Proc.Name);
if (oldProc != null &&
oldProc.DependencyChecksum != currentImplementation.Proc.DependencyChecksum &&
currentImplementation.ExplicitAssumptionAboutCachedPrecondition == null)
{
var axioms = new List <Axiom>();
var after = new List <Cmd>();
Expr assumedExpr = new LiteralExpr(Token.NoToken, false);
var canUseSpecs = DependencyCollector.CanExpressOldSpecs(oldProc, Program, true);
if (canUseSpecs && oldProc.SignatureEquals(currentImplementation.Proc))
{
var always = Substituter.SubstitutionFromHashtable(currentImplementation.GetImplFormalMap(), true,
currentImplementation.Proc);
var forOld = Substituter.SubstitutionFromHashtable(new Dictionary <Variable, Expr>());
var clauses = oldProc.Requires.Select(r =>
Substituter.FunctionCallReresolvingApply(always, forOld, r.Condition, Program));
var conj = Expr.And(clauses, true);
assumedExpr = conj != null
? FunctionExtractor.Extract(conj, Program, axioms)
: new LiteralExpr(Token.NoToken, true);
}
if (assumedExpr != null)
{
var lv = new LocalVariable(Token.NoToken,
new TypedIdent(Token.NoToken, string.Format("a##cached##{0}", FreshAssumptionVariableName), Type.Bool),
new QKeyValue(Token.NoToken, "assumption", new List <object>(), null));
currentImplementation.InjectAssumptionVariable(lv, !canUseSpecs);
var lhs = new SimpleAssignLhs(Token.NoToken, new IdentifierExpr(Token.NoToken, lv));
var rhs = LiteralExpr.And(new IdentifierExpr(Token.NoToken, lv), assumedExpr);
var assumed = new AssignCmd(currentImplementation.tok, new List <AssignLhs> {
lhs
}, new List <Expr> {
rhs
});
assumed.IrrelevantForChecksumComputation = true;
currentImplementation.ExplicitAssumptionAboutCachedPrecondition = assumed;
after.Add(assumed);
}
if (CommandLineOptions.Clo.TraceCachingForTesting || CommandLineOptions.Clo.TraceCachingForBenchmarking)
{
using (var tokTxtWr = new TokenTextWriter("<console>", Console.Out, false, false))
{
var loc = currentImplementation.tok != null && currentImplementation.tok != Token.NoToken
? string.Format("{0}({1},{2})", currentImplementation.tok.filename, currentImplementation.tok.line,
currentImplementation.tok.col)
: "<unknown location>";
Console.Out.WriteLine("Processing implementation {0} (at {1}):", currentImplementation.Name, loc);
foreach (var a in axioms)
{
Console.Out.Write(" >>> added axiom: ");
a.Expr.Emit(tokTxtWr);
Console.Out.WriteLine();
}
foreach (var b in after)
{
Console.Out.Write(" >>> added after assuming the current precondition: ");
b.Emit(tokTxtWr, 0);
}
}
}
}
#endregion
var result = VisitImplementation(currentImplementation);
currentImplementation = null;
this.programInCachedSnapshot = null;
return(result);
}
public static Expr Extract(Expr expr, Program program, List<Axiom> axioms)
{
Contract.Requires(expr != null && program != null && !program.TopLevelDeclarationsAreFrozen && axioms != null);
if (expr is LiteralExpr)
{
return expr;
}
var extractor = new FunctionExtractor();
var body = extractor.VisitExpr(expr);
var name = program.FreshExtractedFunctionName();
var originalVars = extractor.Substitutions.Keys.ToList();
var formalInArgs = originalVars.Select(v => new Formal(Token.NoToken, new TypedIdent(Token.NoToken, extractor.Substitutions[v].Name, extractor.Substitutions[v].TypedIdent.Type), true)).ToList<Variable>();
var formalOutArg = new Formal(Token.NoToken, new TypedIdent(Token.NoToken, name + "$result$", expr.Type), false);
var func = new Function(Token.NoToken, name, formalInArgs, formalOutArg);
func.AddAttribute("never_pattern");
var boundVars = originalVars.Select(k => extractor.Substitutions[k]);
var axiomCall = new NAryExpr(Token.NoToken, new FunctionCall(func), boundVars.Select(b => new IdentifierExpr(Token.NoToken, b)).ToList<Expr>());
axiomCall.Type = expr.Type;
axiomCall.TypeParameters = SimpleTypeParamInstantiation.EMPTY;
var eq = LiteralExpr.Eq(axiomCall, body);
eq.Type = body.Type;
eq.TypeParameters = SimpleTypeParamInstantiation.EMPTY;
if (0 < formalInArgs.Count)
{
var forallExpr = new ForallExpr(Token.NoToken, boundVars.ToList<Variable>(), new Trigger(Token.NoToken, true, new List<Expr> { axiomCall }), eq);
body = forallExpr;
forallExpr.Attributes = new QKeyValue(Token.NoToken, "weight", new List<object> { new LiteralExpr(Token.NoToken, Basetypes.BigNum.FromInt(30)) }, null);
body.Type = Type.Bool;
}
else
{
body = eq;
}
var axiom = new Axiom(Token.NoToken, body);
func.DefinitionAxiom = axiom;
program.AddTopLevelDeclaration(func);
program.AddTopLevelDeclaration(axiom);
axioms.Add(axiom);
var call = new NAryExpr(Token.NoToken, new FunctionCall(func), originalVars.Select(v => new IdentifierExpr(Token.NoToken, v)).ToList<Expr>());
call.Type = expr.Type;
call.TypeParameters = SimpleTypeParamInstantiation.EMPTY;
return call;
}
