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Better resource handling in minimization.

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* src/tgbatest/ltl2tgba.cc (main): Delete the minimized automaton.
* src/tgbaalgos/minimize.cc (minimize): Remove the call to
unregister_variable() at the end.  It was both
wrong (unregistering only the first variable) and useless ("delete
del_a" will unregister all these variables).  Use a map and a set
to keep track of free BDD variable and reuse them, otherwise the
algorithm would sometimes use more variables than allocated.
This commit is contained in:
Alexandre Duret-Lutz 2010-04-12 18:21:50 +02:00
parent 0af8d03261
commit f9e84ac245
3 changed files with 74 additions and 27 deletions
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12
ChangeLog
View file

@ -1,3 +1,15 @@
2010-04-13 Alexandre Duret-Lutz <adl@lrde.epita.fr>
Better resource handling in minimization.
* src/tgbatest/ltl2tgba.cc (main): Delete the minimized automaton.
* src/tgbaalgos/minimize.cc (minimize): Remove the call to
unregister_variable() at the end. It was both
wrong (unregistering only the first variable) and useless ("delete
del_a" will unregister all these variables). Use a map and a set
to keep track of free BDD variable and reuse them, otherwise the
algorithm would sometimes use more variables than allocated.
2010-03-20 Alexandre Duret-Lutz <adl@lrde.epita.fr>
Implement is_safety_automaton().

88
src/tgbaalgos/minimize.cc
View file

@ -1,4 +1,4 @@
// Copyright (C) 2010 Laboratoire de Recherche et Développement
// Copyright (C) 2010 Laboratoire de Recherche et Développement
// de l'Epita (LRDE).
//
// This file is part of Spot, a model checking library.
@ -33,11 +33,9 @@ namespace spot
// Given an automaton a, find all states that are not in "final" and add
// them to the set "non_final".
// "state_set_map" gives corresponding set for each state.
void init_sets(const tgba_explicit* a,
hash_set& final,
hash_set& non_final,
hash_map& state_set_map)
hash_set& non_final)
{
hash_set seen;
std::queue<const state*> tovisit;
@ -51,13 +49,8 @@ namespace spot
tovisit.pop();
// Is the state final ?
if (final.find(src) == final.end())
{
// No, add it to the set non_final
non_final.insert(src);
state_set_map[src] = 0;
}
else
state_set_map[src] = 1;
tgba_succ_iterator* sit = a->succ_iter(src);
for (sit->first(); !sit->done(); sit->next())
{
@ -147,20 +140,48 @@ namespace spot
std::list<const state*>::iterator li;
for (li = acc_list.begin(); li != acc_list.end(); ++li)
final->insert(*li);
init_sets(det_a, *final, *non_final, state_set_map);
init_sets(det_a, *final, *non_final);
// Size of det_a
unsigned size = final->size() + non_final->size();
unsigned bdd_offset = dict->register_anonymous_variables(size, det_a);
// Use bdd variables to number sets. set_num is the first variable
// available.
unsigned set_num = dict->register_anonymous_variables(size, det_a);
std::set<int> free_var;
for (unsigned i = set_num; i < set_num + size; ++i)
free_var.insert(i);
std::map<int, int> used_var;
if (!final->empty())
{
unsigned s = final->size();
used_var[set_num] = s;
free_var.erase(set_num);
if (s > 1)
todo.push(final);
else
done.push_back(final);
for (hash_set::const_iterator i = final->begin();
i != final->end(); ++i)
state_set_map[*i] = set_num;
}
if (!non_final->empty())
{
unsigned s = non_final->size();
unsigned num = set_num + 1;
used_var[num] = s;
free_var.erase(num);
if (s > 1)
todo.push(non_final);
else
done.push_back(non_final);
for (hash_set::const_iterator i = non_final->begin();
i != non_final->end(); ++i)
state_set_map[*i] = num;
}
hash_set* final_copy = new hash_set(*final);
if (final->size() > 1)
todo.push(final);
else if (!final->empty())
done.push_back(final);
if (non_final->size() > 1)
todo.push(non_final);
else if (!non_final->empty())
done.push_back(non_final);
unsigned set_num = 1;
// A bdd_states_map is a list of formulae (in a BDD form) associated with a
// destination set of states.
typedef std::list<std::pair<bdd, hash_set*> > bdd_states_map;
@ -182,7 +203,7 @@ namespace spot
const state* dst = si->current_state();
unsigned dst_set = state_set_map[dst];
delete dst;
f |= (bdd_ithvar(bdd_offset + dst_set) & si->current_condition());
f |= (bdd_ithvar(dst_set) & si->current_condition());
}
delete si;
bdd_states_map::iterator bsi;
@ -213,11 +234,25 @@ namespace spot
for (; bsi != bdd_map.end(); ++bsi)
{
hash_set* set = bsi->second;
// Give a new number for new states.
++set_num;
hash_set::iterator hit;
for (hit = set->begin(); hit != set->end(); ++hit)
state_set_map[*hit] = set_num;
// Free the number associated to these states.
unsigned num = state_set_map[*set->begin()];
assert(used_var.find(num) != used_var.end());
unsigned left = (used_var[num] -= set->size());
// Make sure LEFT does not become negative (hence bigger
// than SIZE when read as unsigned)
assert(left < size);
if (left == 0)
{
used_var.erase(num);
free_var.insert(num);
}
// Pick a free number
assert(!free_var.empty());
num = *free_var.begin();
free_var.erase(free_var.begin());
used_var[num] = set->size();
for (hash_set::iterator hit = set->begin(); hit != set->end(); ++hit)
state_set_map[*hit] = num;
// Trivial sets can't be splitted any further.
if (set->size() == 1)
done.push_back(set);
@ -231,7 +266,6 @@ namespace spot
// Build the result.
tgba_explicit_number* res = build_result(det_a, done, final_copy);
dict->unregister_variable(bdd_offset, det_a);
// Free all the allocated memory.
delete final_copy;
hash_map::iterator hit;

1
src/tgbatest/ltl2tgba.cc
View file

@ -1247,6 +1247,7 @@ main(int argc, char** argv)
delete system;
delete expl;
delete aut_red;
delete minimized;
delete degeneralized;
delete aut_scc;
delete state_labeled;