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spot/src/tgbaalgos/stutter.cc
Alexandre Duret-Lutz a18327d488 stutter: improve closure 
if a transition with the same label already exist, reuse it

* src/tgbaalgos/stutter.cc: Here.
* src/tgbatest/stutter.test: Add a test case.
2015-03-31 19:18:41 +02:00

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// -*- coding: utf-8 -*-
// Copyright (C) 2014, 2015 Laboratoire de Recherche
// et Développement de l'Epita (LRDE).
//
// This file is part of Spot, a model checking library.
//
// Spot is free software; you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 3 of the License, or
// (at your option) any later version.
//
// Spot is distributed in the hope that it will be useful, but WITHOUT
// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
// or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
// License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
#include "stutter.hh"
#include "tgba/tgba.hh"
#include "dupexp.hh"
#include "misc/hash.hh"
#include "misc/hashfunc.hh"
#include "ltlvisit/apcollect.hh"
#include "translate.hh"
#include "ltlast/unop.hh"
#include "ltlvisit/remove_x.hh"
#include "tgbaalgos/product.hh"
#include "tgba/tgbaproduct.hh"
#include "tgba/bddprint.hh"
#include <deque>
#include <unordered_map>
#include <unordered_set>
#include <vector>
namespace spot
{
namespace
{
class state_tgbasl: public state
{
public:
state_tgbasl(state* s, bdd cond) : s_(s), cond_(cond)
{
}
virtual
~state_tgbasl()
{
s_->destroy();
}
virtual int
compare(const state* other) const
{
const state_tgbasl* o =
down_cast<const state_tgbasl*>(other);
assert(o);
int res = s_->compare(o->real_state());
if (res != 0)
return res;
return cond_.id() - o->cond_.id();
}
virtual size_t
hash() const
{
return wang32_hash(s_->hash()) ^ wang32_hash(cond_.id());
}
virtual
state_tgbasl* clone() const
{
return new state_tgbasl(*this);
}
state*
real_state() const
{
return s_;
}
bdd
cond() const
{
return cond_;
}
private:
state* s_;
bdd cond_;
};
class tgbasl_succ_iterator : public tgba_succ_iterator
{
public:
tgbasl_succ_iterator(tgba_succ_iterator* it, const state_tgbasl* state,
bdd_dict_ptr d, bdd atomic_propositions)
: it_(it), state_(state), aps_(atomic_propositions), d_(d)
{
}
virtual
~tgbasl_succ_iterator()
{
delete it_;
}
// iteration
bool
first()
{
loop_ = false;
done_ = false;
need_loop_ = true;
if (it_->first())
{
cond_ = it_->current_condition();
next_edge();
}
return true;
}
bool
next()
{
if (cond_ != bddfalse)
{
next_edge();
return true;
}
if (!it_->next())
{
if (loop_ || !need_loop_)
done_ = true;
loop_ = true;
return !done_;
}
else
{
cond_ = it_->current_condition();
next_edge();
return true;
}
}
bool
done() const
{
return it_->done() && done_;
}
// inspection
state_tgbasl*
current_state() const
{
if (loop_)
return new state_tgbasl(state_->real_state(), state_->cond());
return new state_tgbasl(it_->current_state(), one_);
}
bdd
current_condition() const
{
if (loop_)
return state_->cond();
return one_;
}
acc_cond::mark_t
current_acceptance_conditions() const
{
if (loop_)
return 0U;
return it_->current_acceptance_conditions();
}
private:
void
next_edge()
{
one_ = bdd_satoneset(cond_, aps_, bddtrue);
cond_ -= one_;
if (need_loop_ && (state_->cond() == one_)
&& (state_ == it_->current_state()))
need_loop_ = false;
}
tgba_succ_iterator* it_;
const state_tgbasl* state_;
bdd cond_;
bdd one_;
bdd aps_;
bdd_dict_ptr d_;
bool loop_;
bool need_loop_;
bool done_;
};
class tgbasl final : public tgba
{
public:
tgbasl(const const_tgba_ptr& a, bdd atomic_propositions)
: tgba(a->get_dict()), a_(a), aps_(atomic_propositions)
{
get_dict()->register_all_propositions_of(&a_, this);
assert(acc_.num_sets() == 0);
acc_.add_sets(a_->acc().num_sets());
acc_.set_generalized_buchi();
}
virtual ~tgbasl()
{
get_dict()->unregister_all_my_variables(this);
}
virtual state* get_init_state() const override
{
return new state_tgbasl(a_->get_init_state(), bddfalse);
}
virtual tgba_succ_iterator* succ_iter(const state* state) const override
{
const state_tgbasl* s = down_cast<const state_tgbasl*>(state);
assert(s);
return new tgbasl_succ_iterator(a_->succ_iter(s->real_state()), s,
a_->get_dict(), aps_);
}
virtual std::string format_state(const state* state) const override
{
const state_tgbasl* s = down_cast<const state_tgbasl*>(state);
assert(s);
return (a_->format_state(s->real_state())
+ ", "
+ bdd_format_formula(a_->get_dict(), s->cond()));
}
protected:
virtual bdd compute_support_conditions(const state*) const override
{
return bddtrue;
}
private:
const_tgba_ptr a_;
bdd aps_;
};
typedef std::shared_ptr<tgbasl> tgbasl_ptr;
inline tgbasl_ptr make_tgbasl(const const_tgba_ptr& aut, bdd ap)
{
return std::make_shared<tgbasl>(aut, ap);
}
typedef std::pair<unsigned, bdd> stutter_state;
struct stutter_state_hash
{
size_t
operator()(const stutter_state& s) const
{
return wang32_hash(s.first) ^ wang32_hash(s.second.id());
}
};
// Associate the stutter state to its number.
typedef std::unordered_map<stutter_state, unsigned,
stutter_state_hash> ss2num_map;
// Queue of state to be processed.
typedef std::deque<stutter_state> queue_t;
static bdd
get_all_ap(const const_tgba_digraph_ptr& a)
{
bdd res = bddtrue;
for (auto& i: a->transitions())
res &= bdd_support(i.cond);
return res;
}
}
tgba_digraph_ptr
sl(const const_tgba_digraph_ptr& a, const ltl::formula* f)
{
bdd aps = f
? atomic_prop_collect_as_bdd(f, a)
: get_all_ap(a);
return sl(a, aps);
}
tgba_digraph_ptr
sl2(const const_tgba_digraph_ptr& a, const ltl::formula* f)
{
bdd aps = f
? atomic_prop_collect_as_bdd(f, a)
: get_all_ap(a);
return sl2(a, aps);
}
tgba_digraph_ptr
sl(const const_tgba_digraph_ptr& a, bdd atomic_propositions)
{
// The result automaton uses numbered states.
tgba_digraph_ptr res = make_tgba_digraph(a->get_dict());
// We use the same BDD variables as the input.
res->copy_ap_of(a);
res->copy_acceptance_of(a);
// These maps make it possible to convert stutter_state to number
// and vice-versa.
ss2num_map ss2num;
queue_t todo;
unsigned s0 = a->get_init_state_number();
stutter_state s(s0, bddfalse);
ss2num[s] = 0;
res->new_state();
todo.push_back(s);
while (!todo.empty())
{
s = todo.front();
todo.pop_front();
unsigned src = ss2num[s];
bool self_loop_needed = true;
for (auto& t : a->out(s.first))
{
bdd all = t.cond;
while (all != bddfalse)
{
bdd one = bdd_satoneset(all, atomic_propositions, bddtrue);
all -= one;
stutter_state d(t.dst, one);
auto r = ss2num.emplace(d, ss2num.size());
unsigned dest = r.first->second;
if (r.second)
{
todo.push_back(d);
unsigned u = res->new_state();
assert(u == dest);
(void)u;
}
// Create the transition.
res->new_transition(src, dest, one, t.acc);
if (src == dest)
self_loop_needed = false;
}
}
if (self_loop_needed && s.second != bddfalse)
res->new_transition(src, src, s.second, 0U);
}
res->merge_transitions();
return res;
}
tgba_digraph_ptr
sl2(tgba_digraph_ptr&& a, bdd atomic_propositions)
{
if (atomic_propositions == bddfalse)
atomic_propositions = get_all_ap(a);
unsigned num_states = a->num_states();
unsigned num_transitions = a->num_transitions();
std::vector<bdd> selfloops(num_states, bddfalse);
std::map<std::pair<unsigned, int>, unsigned> newstates;
// Record all the conditions for which we can selfloop on each
// state.
for (auto& t: a->transitions())
if (t.src == t.dst)
selfloops[t.src] |= t.cond;
for (unsigned t = 1; t <= num_transitions; ++t)
{
auto& td = a->trans_storage(t);
if (a->is_dead_transition(td))
continue;
unsigned src = td.src;
unsigned dst = td.dst;
if (src != dst)
{
bdd all = td.cond;
// If there is a self-loop with the whole condition on
// either end of the transition, do not bother with it.
if (bdd_implies(all, selfloops[src])
|| bdd_implies(all, selfloops[dst]))
continue;
// Do not use td in the loop because the new_transition()
// might invalidate it.
auto acc = td.acc;
while (all != bddfalse)
{
bdd one = bdd_satoneset(all, atomic_propositions, bddtrue);
all -= one;
// Skip if there is a loop for this particular letter.
if (bdd_implies(one, selfloops[src])
|| bdd_implies(one, selfloops[dst]))
continue;
auto p = newstates.emplace(std::make_pair(dst, one.id()), 0);
if (p.second)
p.first->second = a->new_state();
unsigned tmp = p.first->second; // intermediate state
unsigned i = a->new_transition(src, tmp, one, acc);
assert(i > num_transitions);
i = a->new_transition(tmp, tmp, one, 0U);
assert(i > num_transitions);
// No acceptance here to preserve the state-based property.
i = a->new_transition(tmp, dst, one, 0U);
assert(i > num_transitions);
(void)i;
}
}
}
if (num_states != a->num_states())
a->prop_keep({true, // state_based
false, // inherently_weak
false, // deterministic
false, // stutter inv.
});
a->merge_transitions();
return a;
}
tgba_digraph_ptr
sl2(const const_tgba_digraph_ptr& a, bdd atomic_propositions)
{
return sl2(make_tgba_digraph(a, tgba::prop_set::all()),
atomic_propositions);
}
tgba_digraph_ptr
closure(tgba_digraph_ptr&& a)
{
a->prop_keep({false, // state_based
false, // inherently_weak
false, // deterministic
false, // stutter inv.
});
unsigned n = a->num_states();
std::vector<unsigned> todo;
std::vector<std::vector<unsigned> > dst2trans(n);
for (unsigned state = 0; state < n; ++state)
{
auto trans = a->out(state);
for (auto it = trans.begin(); it != trans.end(); ++it)
{
todo.push_back(it.trans());
dst2trans[it->dst].push_back(it.trans());
}
while (!todo.empty())
{
auto t1 = a->trans_storage(todo.back());
todo.pop_back();
for (auto& t2 : a->out(t1.dst))
{
bdd cond = t1.cond & t2.cond;
if (cond != bddfalse)
{
bool need_new_trans = true;
acc_cond::mark_t acc = t1.acc | t2.acc;
for (auto& t: dst2trans[t2.dst])
{
auto& ts = a->trans_storage(t);
if (acc == ts.acc)
{
if (!bdd_implies(cond, ts.cond))
{
ts.cond |= cond;
if (std::find(todo.begin(), todo.end(), t)
== todo.end())
todo.push_back(t);
}
need_new_trans = false;
break;
}
else if (cond == ts.cond)
{
acc |= ts.acc;
if (ts.acc != acc)
{
ts.acc = acc;
if (std::find(todo.begin(), todo.end(), t)
== todo.end())
todo.push_back(t);
}
need_new_trans = false;
break;
}
}
if (need_new_trans)
{
// Load t2.dst first, because t2 can be
// invalidated by new_transition().
auto dst = t2.dst;
auto i = a->new_transition(state, dst, cond, acc);
dst2trans[dst].push_back(i);
todo.push_back(i);
}
}
}
}
for (auto& it: dst2trans)
it.clear();
}
return a;
}
tgba_digraph_ptr
closure(const const_tgba_digraph_ptr& a)
{
return closure(make_tgba_digraph(a, {true, true, true, false}));
}
// The stutter check algorithm to use can be overridden via an
// environment variable.
static int default_stutter_check_algorithm()
{
static const char* stutter_check = getenv("SPOT_STUTTER_CHECK");
if (stutter_check)
{
char* endptr;
long res = strtol(stutter_check, &endptr, 10);
if (*endptr || res < 0 || res > 8)
throw
std::runtime_error("invalid value for SPOT_STUTTER_CHECK.");
return res;
}
else
{
return 8; // The best variant, according to our benchmarks.
}
}
bool
is_stutter_invariant(const ltl::formula* f)
{
if (f->is_ltl_formula() && f->is_syntactic_stutter_invariant())
return true;
int algo = default_stutter_check_algorithm();
if (algo == 0) // Etessami's check via syntactic transformation.
{
if (!f->is_ltl_formula())
throw std::runtime_error("Cannot use the syntactic "
"stutter-invariance check "
"for non-LTL formulas");
const ltl::formula* g = remove_x(f);
ltl::ltl_simplifier ls;
bool res = ls.are_equivalent(f, g);
g->destroy();
return res;
}
// Prepare for an automata-based check.
const ltl::formula* nf = ltl::unop::instance(ltl::unop::Not, f->clone());
translator trans;
auto aut_f = trans.run(f);
auto aut_nf = trans.run(nf);
bdd aps = atomic_prop_collect_as_bdd(f, aut_f);
nf->destroy();
return is_stutter_invariant(std::move(aut_f), std::move(aut_nf), aps, algo);
}
bool
is_stutter_invariant(tgba_digraph_ptr&& aut_f,
tgba_digraph_ptr&& aut_nf, bdd aps, int algo)
{
if (algo == 0)
algo = default_stutter_check_algorithm();
switch (algo)
{
case 1: // sl(aut_f) x sl(aut_nf)
return product(sl(std::move(aut_f), aps),
sl(std::move(aut_nf), aps))->is_empty();
case 2: // sl(cl(aut_f)) x aut_nf
return product(sl(closure(std::move(aut_f)), aps),
std::move(aut_nf))->is_empty();
case 3: // (cl(sl(aut_f)) x aut_nf
return product(closure(sl(std::move(aut_f), aps)),
std::move(aut_nf))->is_empty();
case 4: // sl2(aut_f) x sl2(aut_nf)
return product(sl2(std::move(aut_f), aps),
sl2(std::move(aut_nf), aps))->is_empty();
case 5: // sl2(cl(aut_f)) x aut_nf
return product(sl2(closure(std::move(aut_f)), aps),
std::move(aut_nf))->is_empty();
case 6: // (cl(sl2(aut_f)) x aut_nf
return product(closure(sl2(std::move(aut_f), aps)),
std::move(aut_nf))->is_empty();
case 7: // on-the-fly sl(aut_f) x sl(aut_nf)
return otf_product(make_tgbasl(aut_f, aps),
make_tgbasl(aut_nf, aps))->is_empty();
case 8: // cl(aut_f) x cl(aut_nf)
return product(closure(std::move(aut_f)),
closure(std::move(aut_nf)))->is_empty();
default:
throw std::runtime_error("invalid algorithm number for "
"is_stutter_invariant()");
SPOT_UNREACHABLE();
}
}
}
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