bool RewriteMatchingLoop()
{
if (expr is QuantifierExpr)
{
QuantifierExpr quantifier = (QuantifierExpr)expr;
var l = new List <QuantifierWithTriggers>();
List <Expression> splits = new List <Expression>();
bool rewritten = false;
foreach (var q in quantifiers)
{
if (TriggerUtils.NeedsAutoTriggers(q.quantifier) && TriggerUtils.WantsMatchingLoopRewrite(q.quantifier))
{
var matchingLoopRewriter = new MatchingLoopRewriter();
var qq = matchingLoopRewriter.RewriteMatchingLoops(q);
splits.Add(qq);
l.Add(new QuantifierWithTriggers(qq));
rewritten = true;
}
else
{
// don't rewrite the quantifier if we are not auto generate triggers.
// This is because rewriting introduces new boundvars and will cause
// user provided triggers not mention all boundvars
splits.Add(q.quantifier);
l.Add(q);
}
}
if (rewritten)
{
quantifier.SplitQuantifier = splits;
quantifiers = l;
return(true);
}
}
return(false);
}
private static bool ShallowEq(LiteralExpr expr1, LiteralExpr expr2)
{
if (!TriggerUtils.SameNullity(expr1.Value, expr2.Value) || (expr1.Value != null && !expr1.Value.Equals(expr2.Value)))
{
return(false);
}
if (expr1 is StringLiteralExpr && expr2 is StringLiteralExpr)
{
return(ShallowEq((StringLiteralExpr)expr1, (StringLiteralExpr)expr2));
}
else if (expr1 is CharLiteralExpr && expr2 is CharLiteralExpr)
{
return(ShallowEq((CharLiteralExpr)expr1, (CharLiteralExpr)expr2));
}
else if (expr1 is StaticReceiverExpr && expr2 is StaticReceiverExpr)
{
return(ShallowEq((StaticReceiverExpr)expr1, (StaticReceiverExpr)expr2));
}
else
{
return(expr1.GetType() == expr2.GetType()); // LiteralExpr is not abstract
}
}
/// <summary>
/// Collect triggers from the body of each quantifier, and share them
/// between all quantifiers. This method assumes that all quantifiers
/// actually come from the same context, and were the result of a split that
/// gave them all the same variables.
/// </summary>
/// <param name="triggersCollector"></param>
void CollectAndShareTriggers(TriggersCollector triggersCollector)
{
List <TriggerTerm> pool = new List <TriggerTerm>();
foreach (var q in quantifiers)
{
var candidates = triggersCollector.CollectTriggers(q.quantifier).Deduplicate(TriggerTerm.Eq);
// filter out the candidates that was "second-class"
var filtered = TriggerUtils.Filter(candidates, tr => tr, (tr, _) => !tr.IsTranslatedToFunctionCall(), (tr, _) => { }).ToList();
// if there are only "second-class" candidates, add them back.
if (filtered.Count == 0)
{
filtered = candidates;
}
pool.AddRange(filtered);
}
var distinctPool = pool.Deduplicate(TriggerTerm.Eq);
foreach (var q in quantifiers)
{
q.CandidateTerms = distinctPool; // The list of candidate terms is immutable
q.Candidates = TriggerUtils.AllNonEmptySubsets(distinctPool, SubsetGenerationPredicate, q.quantifier.BoundVars).Select(set => set.ToTriggerCandidate()).ToList();
}
}
public QuantifierExpr RewriteMatchingLoops(QuantifierWithTriggers q)
{
// rewrite quantifier to avoid matching loops
// before:
// assert forall i :: 0 <= i < a.Length-1 ==> a[i] <= a[i+1];
// after:
// assert forall i,j :: j == i+1 ==> 0 <= i < a.Length-1 ==> a[i] <= a[j];
substMap = new List <Tuple <Expression, IdentifierExpr> >();
foreach (var m in q.LoopingMatches)
{
var e = m.OriginalExpr;
if (TriggersCollector.IsPotentialTriggerCandidate(e) && triggersCollector.IsTriggerKiller(e))
{
foreach (var sub in e.SubExpressions)
{
if (triggersCollector.IsTriggerKiller(sub) && (!TriggersCollector.IsPotentialTriggerCandidate(sub)))
{
var entry = substMap.Find(x => ExprExtensions.ExpressionEq(sub, x.Item1));
if (entry == null)
{
var newBv = new BoundVar(sub.tok, "_t#" + substMap.Count, sub.Type);
var ie = new IdentifierExpr(sub.tok, newBv.Name);
ie.Var = newBv;
ie.Type = newBv.Type;
substMap.Add(new Tuple <Expression, IdentifierExpr>(sub, ie));
}
}
}
}
}
var expr = (QuantifierExpr)q.quantifier;
if (substMap.Count > 0)
{
var s = new Translator.ExprSubstituter(substMap);
expr = s.Substitute(q.quantifier) as QuantifierExpr;
}
else
{
// make a copy of the expr
if (expr is ForallExpr)
{
expr = new ForallExpr(expr.tok, expr.TypeArgs, expr.BoundVars, expr.Range, expr.Term, TriggerUtils.CopyAttributes(expr.Attributes))
{
Type = expr.Type, Bounds = expr.Bounds
};
}
else
{
expr = new ExistsExpr(expr.tok, expr.TypeArgs, expr.BoundVars, expr.Range, expr.Term, TriggerUtils.CopyAttributes(expr.Attributes))
{
Type = expr.Type, Bounds = expr.Bounds
};
}
}
return(expr);
}
internal static IEnumerable <Expression> SplitQuantifier(ComprehensionExpr quantifier)
{
var body = quantifier.Term;
var binary = body as BinaryExpr;
if (quantifier is ForallExpr)
{
IEnumerable <Expression> stream;
if (binary != null && (binary.Op == BinaryExpr.Opcode.Imp || binary.Op == BinaryExpr.Opcode.Or))
{
stream = SplitAndStich(binary, BinaryExpr.Opcode.And);
}
else
{
stream = SplitExpr(body, BinaryExpr.Opcode.And);
}
foreach (var e in stream)
{
var tok = new NestedToken(quantifier.tok, e.tok);
yield return(new ForallExpr(tok, ((ForallExpr)quantifier).TypeArgs, quantifier.BoundVars, quantifier.Range, e, TriggerUtils.CopyAttributes(quantifier.Attributes))
{
Type = quantifier.Type, Bounds = quantifier.Bounds
});
}
}
else if (quantifier is ExistsExpr)
{
IEnumerable <Expression> stream;
if (binary != null && binary.Op == BinaryExpr.Opcode.And)
{
stream = SplitAndStich(binary, BinaryExpr.Opcode.Or);
}
else
{
stream = SplitExpr(body, BinaryExpr.Opcode.Or);
}
foreach (var e in stream)
{
var tok = new NestedToken(quantifier.tok, e.tok);
yield return(new ExistsExpr(tok, ((ExistsExpr)quantifier).TypeArgs, quantifier.BoundVars, quantifier.Range, e, TriggerUtils.CopyAttributes(quantifier.Attributes))
{
Type = quantifier.Type, Bounds = quantifier.Bounds
});
}
}
else
{
yield return(quantifier);
}
}
private static bool ShallowEq(MemberSelectExpr expr1, MemberSelectExpr expr2)
{
return(expr1.MemberName == expr2.MemberName &&
expr1.Member == expr2.Member &&
TriggerUtils.SameLists(expr1.TypeApplication, expr2.TypeApplication, TypeEq));
}
private static bool ShallowEq(NamedExpr expr1, NamedExpr expr2)
{
return(expr1.Name == expr2.Name &&
TriggerUtils.SameNullity(expr1.Contract, expr2.Contract));
}
private static bool ShallowSameAttributes(Attributes attributes1, Attributes attributes2)
{
return(TriggerUtils.SameLists(attributes1.AsEnumerable(), attributes2.AsEnumerable(), ShallowSameSingleAttribute));
}
internal static IEnumerable <TriggerMatch> SubexpressionsMatchingTrigger(this ComprehensionExpr quantifier, Expression trigger)
{
return(quantifier.AllSubExpressions(true, true, true)
.Select(e => TriggerUtils.PrepareExprForInclusionInTrigger(e).MatchAgainst(trigger, quantifier.BoundVars, e))
.Where(e => e.HasValue).Select(e => e.Value));
}
private TriggerAnnotation Annotate(Expression expr)
{
TriggerAnnotation cached;
if (cache.annotations.TryGetValue(expr, out cached))
{
return(cached);
}
TriggerAnnotation annotation = null; // TODO: Using ApplySuffix fixes the unresolved members problem in GenericSort
if (expr is LetExpr)
{
var le = (LetExpr)expr;
if (le.LHSs.All(p => p.Var != null) && le.Exact)
{
// Inline the let expression before doing trigger selection.
annotation = Annotate(Translator.InlineLet(le));
}
}
if (annotation == null)
{
expr.SubExpressions.Iter(e => Annotate(e));
if (IsPotentialTriggerCandidate(expr))
{
annotation = AnnotatePotentialCandidate(expr);
}
else if (expr is QuantifierExpr)
{
annotation = AnnotateQuantifier((QuantifierExpr)expr);
}
else if (expr is LetExpr)
{
annotation = AnnotateLetExpr((LetExpr)expr);
}
else if (expr is IdentifierExpr)
{
annotation = AnnotateIdentifier((IdentifierExpr)expr);
}
else if (expr is ApplySuffix)
{
annotation = AnnotateApplySuffix((ApplySuffix)expr);
}
else if (expr is MatchExpr)
{
annotation = AnnotateMatchExpr((MatchExpr)expr);
}
else if (expr is ComprehensionExpr)
{
annotation = AnnotateComprehensionExpr((ComprehensionExpr)expr);
}
else if (expr is ConcreteSyntaxExpression ||
expr is LiteralExpr ||
expr is ThisExpr ||
expr is BoxingCastExpr ||
expr is MultiSetFormingExpr ||
expr is SeqConstructionExpr)
{
annotation = AnnotateOther(expr, false);
}
else
{
annotation = AnnotateOther(expr, true);
}
}
TriggerUtils.DebugTriggers("{0} ({1})\n{2}", Printer.ExprToString(expr), expr.GetType(), annotation);
cache.annotations[expr] = annotation;
return(annotation);
}
private void CommitOne(QuantifierWithTriggers q, bool addHeader)
{
var errorLevel = ErrorLevel.Info;
var msg = new StringBuilder();
var indent = addHeader ? " " : "";
bool suppressWarnings = Attributes.Contains(q.quantifier.Attributes, "nowarn");
if (!TriggerUtils.NeedsAutoTriggers(q.quantifier)) // NOTE: split and autotriggers attributes are passed down to Boogie
{
var extraMsg = TriggerUtils.WantsAutoTriggers(q.quantifier) ? "" : " Note that {:autotriggers false} can cause instabilities. Consider using {:nowarn}, {:matchingloop} (not great either), or a manual trigger instead.";
msg.AppendFormat("Not generating triggers for \"{0}\".{1}", Printer.ExprToString(q.quantifier.Term), extraMsg).AppendLine();
}
else
{
if (addHeader)
{
msg.AppendFormat("For expression \"{0}\":", Printer.ExprToString(q.quantifier.Term)).AppendLine();
}
foreach (var candidate in q.Candidates)
{
q.quantifier.Attributes = new Attributes("trigger", candidate.Terms.Select(t => t.Expr).ToList(), q.quantifier.Attributes);
}
AddTriggersToMessage("Selected triggers:", q.Candidates, msg, indent);
AddTriggersToMessage("Rejected triggers:", q.RejectedCandidates, msg, indent, true);
#if QUANTIFIER_WARNINGS
var WARN_TAG = ArmadaOptions.O.UnicodeOutput ? "⚠ " : "/!\\ ";
var WARN_TAG_OVERRIDE = suppressWarnings ? "(Suppressed warning) " : WARN_TAG;
var WARN_LEVEL = suppressWarnings ? ErrorLevel.Info : ErrorLevel.Warning;
var WARN = indent + WARN_TAG_OVERRIDE;
if (!q.CandidateTerms.Any())
{
errorLevel = WARN_LEVEL;
msg.Append(WARN).AppendLine("No terms found to trigger on.");
}
else if (!q.Candidates.Any())
{
errorLevel = WARN_LEVEL;
msg.Append(WARN).AppendLine("No trigger covering all quantified variables found.");
}
else if (!q.CouldSuppressLoops && !q.AllowsLoops)
{
errorLevel = WARN_LEVEL;
msg.Append(WARN).AppendLine("Suppressing loops would leave this expression without triggers.");
}
else if (suppressWarnings)
{
errorLevel = ErrorLevel.Warning;
msg.Append(indent).Append(WARN_TAG).AppendLine("There is no warning here to suppress.");
}
#endif
}
if (msg.Length > 0)
{
var msgStr = msg.ToString().TrimEnd("\r\n ".ToCharArray());
reporter.Message(MessageSource.Rewriter, errorLevel, q.quantifier.tok, msgStr);
}
}
private static bool SameTriggerCandidate(TriggerCandidate arg1, TriggerCandidate arg2)
{
return(TriggerUtils.SameLists(arg1.Terms, arg2.Terms, TriggerTerm.Eq));
}
private bool HasSameTriggers(QuantifierWithTriggers one, QuantifierWithTriggers other)
{
return(TriggerUtils.SameLists(one.Candidates, other.Candidates, SameTriggerCandidate));
}
internal void TrimInvalidTriggers()
{
Contract.Requires(CandidateTerms != null);
Contract.Requires(Candidates != null);
Candidates = TriggerUtils.Filter(Candidates, tr => tr, (tr, _) => tr.MentionsAll(quantifier.BoundVars), (tr, _) => { }).ToList();
}
// group split quantifier by what triggers they got, and merged them back into one quantifier.
private void CombineSplitQuantifier()
{
if (quantifiers.Count > 1)
{
List <QuantifierGroup> groups = new List <QuantifierGroup>();
groups.Add(new QuantifierGroup(quantifiers[0], new List <ComprehensionExpr> {
quantifiers[0].quantifier
}));
for (int i = 1; i < quantifiers.Count; i++)
{
bool found = false;
for (int j = 0; j < groups.Count; j++)
{
if (HasSameTriggers(quantifiers[i], groups[j].quantifier))
{
// belong to the same group
groups[j].expressions.Add(quantifiers[i].quantifier);
found = true;
break;
}
}
if (!found)
{
// start a new group
groups.Add(new QuantifierGroup(quantifiers[i], new List <ComprehensionExpr> {
quantifiers[i].quantifier
}));
}
}
if (groups.Count == quantifiers.Count)
{
// have the same number of splits, so no splits are combined.
return;
}
// merge expressions in each group back to one quantifier.
List <QuantifierWithTriggers> list = new List <QuantifierWithTriggers>();
List <Expression> splits = new List <Expression>();
foreach (var group in groups)
{
QuantifierWithTriggers q = group.quantifier;
if (q.quantifier is ForallExpr)
{
ForallExpr quantifier = (ForallExpr)q.quantifier;
Expression expr = QuantifiersToExpression(quantifier.tok, BinaryExpr.ResolvedOpcode.And, group.expressions);
q.quantifier = new ForallExpr(quantifier.tok, quantifier.TypeArgs, quantifier.BoundVars, quantifier.Range, expr, TriggerUtils.CopyAttributes(quantifier.Attributes))
{
Type = quantifier.Type, Bounds = quantifier.Bounds
};
}
else if (q.quantifier is ExistsExpr)
{
ExistsExpr quantifier = (ExistsExpr)q.quantifier;
Expression expr = QuantifiersToExpression(quantifier.tok, BinaryExpr.ResolvedOpcode.Or, group.expressions);
q.quantifier = new ExistsExpr(quantifier.tok, quantifier.TypeArgs, quantifier.BoundVars, quantifier.Range, expr, TriggerUtils.CopyAttributes(quantifier.Attributes))
{
Type = quantifier.Type, Bounds = quantifier.Bounds
};
}
list.Add(q);
splits.Add(q.quantifier);
}
this.quantifiers = list;
Contract.Assert(this.expr is QuantifierExpr); // only QuantifierExpr has SplitQuantifier
((QuantifierExpr)this.expr).SplitQuantifier = splits;
}
}
