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translate, simplify: limit containment checks of n-ary operators

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Fixes #521.

* spot/tl/simplify.cc, spot/tl/simplify.hh,
spot/twaalgos/translate.cc, spot/twaalgos/translate.hh: Add an option
to limit automata-based implication checks of n-ary operators when too
many operands are used.  Defaults to 16.
* bin/spot-x.cc, NEWS, doc/tl/tl.tex: Document it.
* tests/core/bdd.test: Disable the limit for this test.
This commit is contained in:
Alexandre Duret-Lutz 2022-11-15 17:27:10 +01:00
parent f2c65ea557
commit 843c4cdb91
8 changed files with 33 additions and 11 deletions
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10
spot/tl/simplify.cc
View file

@ -2507,8 +2507,11 @@ namespace spot
unsigned mos = mo.size();
if ((opt_.synt_impl | opt_.containment_checks)
&& mo.is(op::Or, op::And))
&& mo.is(op::Or, op::And)
&& (opt_.containment_max_ops == 0
|| opt_.containment_max_ops >= mos))
{
bool is_and = mo.is(op::And);
// Do not merge these two loops, as rewritings from the
// second loop could prevent rewritings from the first one
// to trigger.
@ -2520,7 +2523,6 @@ namespace spot
// if fo => !fi, then fi & fo = false
// if !fi => fo, then fi | fo = true
// if !fo => fi, then fi | fo = true
bool is_and = mo.is(op::And);
if (c_->implication_neg(fi, fo, is_and)
|| c_->implication_neg(fo, fi, is_and))
return recurse(is_and ? formula::ff() : formula::tt());
@ -2531,8 +2533,8 @@ namespace spot
formula fo = mo.all_but(i);
// if fi => fo, then fi | fo = fo
// if fo => fi, then fi & fo = fo
if ((mo.is(op::Or) && c_->implication(fi, fo))
|| (mo.is(op::And) && c_->implication(fo, fi)))
if (((!is_and) && c_->implication(fi, fo))
|| (is_and && c_->implication(fo, fi)))
{
// We are about to pick fo, but hold on!
// Maybe we actually have fi <=> fo, in

5
spot/tl/simplify.hh
View file

@ -1,5 +1,5 @@
// -*- coding: utf-8 -*-
// Copyright (C) 2011-2017, 2019, 2020 Laboratoire de Recherche et Developpement
// Copyright (C) 2011-2022 Laboratoire de Recherche et Developpement
// de l'Epita (LRDE).
//
// This file is part of Spot, a model checking library.
@ -96,6 +96,9 @@ namespace spot
// If greater than 0, bound the number of states used by automata
// in containment checks.
unsigned containment_max_states = 0;
// If greater than 0, maximal number of terms in a multop to perform
// containment checks on this multop.
unsigned containment_max_ops = 16;
};
// fwd declaration to hide technical details.