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genem: improve the worst case

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* spot/twaalgos/genem.cc, spot/twaalgos/genem.hh: Improve the worst
case by not recurring twice into each disjunct individually.  Keep
the previous two implementation available and add a function
generic_emptiness_check_select_version() so we can benchmark the
difference.
* tests/python/genem.py: Test the three versions.
This commit is contained in:
Alexandre Duret-Lutz 2020-03-06 09:56:16 +01:00
parent 73277bed96
commit 7f0ef7ad59
3 changed files with 100 additions and 28 deletions
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88
spot/twaalgos/genem.cc
View file

@ -23,6 +23,25 @@
namespace spot
{
namespace
{
enum genem_version_t { spot28, atva19, spot29 };
static genem_version_t genem_version = spot29;
}
void generic_emptiness_check_select_version(const char* emversion)
{
if (emversion == nullptr || !strcasecmp(emversion, "spot29"))
genem_version = spot29;
else if (!strcasecmp(emversion, "spot28"))
genem_version = spot28;
else if (!strcasecmp(emversion, "atva19"))
genem_version = atva19;
else
throw std::invalid_argument("generic_emptiness_check version should"
" be one of {spot28, atva19, spot29}");
}
namespace
{
static bool
@ -65,26 +84,55 @@ namespace spot
acc_cond acc = autacc.restrict_to(sets);
acc = acc.remove(si.common_sets_of(scc), false);
for (const acc_cond& disjunct: acc.top_disjuncts())
if (acc_cond::mark_t fu = disjunct.fin_unit())
{
if (!scc_split_check
(si, scc, disjunct.remove(fu, true), run, fu))
return false;
}
else
{
int fo = disjunct.fin_one();
assert(fo >= 0);
// Try to accept when Fin(fo) == true
acc_cond::mark_t fo_m = {(unsigned) fo};
if (!scc_split_check
(si, scc, disjunct.remove(fo_m, true), run, fo_m))
return false;
// Try to accept when Fin(fo) == false
if (!is_scc_empty(si, scc, disjunct.force_inf(fo_m), run, tocut))
return false;
}
auto generic_recurse =
[&] (const acc_cond& subacc)
{
int fo = (SPOT_UNLIKELY(genem_version == spot28)
? acc.fin_one() : subacc.fin_one());
assert(fo >= 0);
// Try to accept when Fin(fo) == true
acc_cond::mark_t fo_m = {(unsigned) fo};
if (!scc_split_check
(si, scc, subacc.remove(fo_m, true), run, fo_m))
return false;
// Try to accept when Fin(fo) == false
if (!is_scc_empty(si, scc, subacc.force_inf(fo_m), run, tocut))
return false;
return true;
};
if (SPOT_LIKELY(genem_version == spot29))
{
acc_cond::acc_code rest = acc_cond::acc_code::f();
for (const acc_cond& disjunct: acc.top_disjuncts())
if (acc_cond::mark_t fu = disjunct.fin_unit())
{
if (!scc_split_check
(si, scc, disjunct.remove(fu, true), run, fu))
return false;
}
else
{
rest |= disjunct.get_acceptance();
}
if (!rest.is_f() && !generic_recurse(acc_cond(acc.num_sets(), rest)))
return false;
}
else
{
for (const acc_cond& disjunct: acc.top_disjuncts())
if (acc_cond::mark_t fu = disjunct.fin_unit())
{
if (!scc_split_check
(si, scc, disjunct.remove(fu, true), run, fu))
return false;
}
else
{
if (!generic_recurse(disjunct))
return false;
}
}
return true;
}

21
spot/twaalgos/genem.hh
View file

@ -1,5 +1,5 @@
// -*- coding: utf-8 -*-
// Copyright (C) 2017-2019 Laboratoire de Recherche et Developpement
// Copyright (C) 2017-2020 Laboratoire de Recherche et Developpement
// de l'Epita (LRDE).
//
// This file is part of Spot, a model checking library.
@ -61,4 +61,23 @@ namespace spot
SPOT_API bool
generic_emptiness_check_for_scc(const scc_info& si, unsigned scc,
const acc_cond& forced_acc);
/// \ingroup emptiness_check_algorithms
///
/// Select the version of the generic-emptiness check to use, this
/// is mainly for benchmarking purpose.
///
/// We currently have three versions:
/// - "spot28" is similar to the algorithm described our ATVA'19 paper
/// \cite baier.19.atva , however it has an implementation bug
/// that cause superfluous recursive calls to be performed (the
/// result is still correct.
/// - "atva19" is similar to the algorithm described our ATVA'19 paper
/// \cite baier.19.atva , with the above bug fixed.
/// - "spot29" improves upon the worst case of atva19. This is
/// the default.
SPOT_API void
generic_emptiness_check_select_version(const char* emversion = nullptr);
}

19
tests/python/genem.py
View file

@ -1,5 +1,5 @@
# -*- mode: python; coding: utf-8 -*-
# Copyright (C) 2018-2019 Laboratoire de Recherche et Développement de l'Epita
# Copyright (C) 2018-2020 Laboratoire de Recherche et Développement de l'Epita
# (LRDE).
#
# This file is part of Spot, a model checking library.
@ -283,17 +283,22 @@ def is_scc_empty2(si, scc_num, acc=None):
def run_bench(automata):
for aut in automata:
# Make sure our three implementation behave identically
# Make sure all our implementations behave identically
res5 = is_empty2(aut)
res4 = is_empty1(aut)
res3 = spot.generic_emptiness_check(aut)
spot.generic_emptiness_check_select_version("spot28")
res3a = spot.generic_emptiness_check(aut)
spot.generic_emptiness_check_select_version("atva19")
res3b = spot.generic_emptiness_check(aut)
spot.generic_emptiness_check_select_version("spot29")
res3c = spot.generic_emptiness_check(aut)
res2 = spot.remove_fin(aut).is_empty()
res1 = generic_emptiness2(aut)
res = (str(res1)[0] + str(res2)[0] + str(res3)[0]
+ str(res4)[0] + str(res5)[0])
res = (str(res1)[0] + str(res2)[0] + str(res3a)[0]
+ str(res3b)[0] + str(res3c)[0] + str(res4)[0] + str(res5)[0])
print(res)
assert res in ('TTTTT', 'FFFFF')
if res == 'FFFFF':
assert res in ('TTTTTTT', 'FFFFFFF')
if res == 'FFFFFFF':
run3 = spot.generic_accepting_run(aut)
assert run3.replay(spot.get_cout()) is True