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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2017-01-30 09:39:23 -08:00
commit a412a554eb
21 changed files with 334 additions and 86 deletions
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1
src/sat/sat_config.cpp
View file

@ -77,6 +77,7 @@ namespace sat {
m_burst_search = p.burst_search();
m_max_conflicts = p.max_conflicts();
m_num_parallel = p.parallel_threads();
// These parameters are not exposed
m_simplify_mult1 = _p.get_uint("simplify_mult1", 300);

1
src/sat/sat_config.h
View file

@ -57,6 +57,7 @@ namespace sat {
unsigned m_random_seed;
unsigned m_burst_search;
unsigned m_max_conflicts;
unsigned m_num_parallel;
unsigned m_simplify_mult1;
double m_simplify_mult2;

59
src/sat/sat_mus.cpp
View file

@ -23,7 +23,7 @@ Notes:
namespace sat {
mus::mus(solver& s):s(s), m_is_active(false),m_restart(0), m_max_restarts(0) {}
mus::mus(solver& s):s(s), m_is_active(false), m_max_num_restarts(UINT_MAX) {}
mus::~mus() {}
@ -31,8 +31,6 @@ namespace sat {
m_core.reset();
m_mus.reset();
m_model.reset();
m_max_restarts = (s.m_stats.m_restart - m_restart) + 10;
m_restart = s.m_stats.m_restart;
}
void mus::set_core() {
@ -49,12 +47,12 @@ namespace sat {
}
lbool mus::operator()() {
m_max_num_restarts = s.m_config.m_core_minimize_partial ? s.num_restarts() + 10 : UINT_MAX;
flet<bool> _disable_min(s.m_config.m_core_minimize, false);
flet<bool> _is_active(m_is_active, true);
IF_VERBOSE(3, verbose_stream() << "(sat.mus " << s.get_core() << ")\n";);
IF_VERBOSE(3, verbose_stream() << "(sat.mus size: " << s.get_core().size() << " core: [" << s.get_core() << "])\n";);
reset();
lbool r = mus1();
m_restart = s.m_stats.m_restart;
return r;
}
@ -63,13 +61,13 @@ namespace sat {
TRACE("sat", tout << "old core: " << s.get_core() << "\n";);
literal_vector& core = get_core();
literal_vector& mus = m_mus;
if (core.size() > 64) {
if (!minimize_partial && core.size() > 64) {
return mus2();
}
unsigned delta_time = 0;
unsigned core_miss = 0;
while (!core.empty()) {
IF_VERBOSE(3, verbose_stream() << "(opt.mus reducing core: " << core.size() << " mus: " << mus.size() << ")\n";);
IF_VERBOSE(1, verbose_stream() << "(sat.mus num-to-process: " << core.size() << " mus: " << mus.size();
if (minimize_partial) verbose_stream() << " max-restarts: " << m_max_num_restarts;
verbose_stream() << ")\n";);
TRACE("sat",
tout << "core: " << core << "\n";
tout << "mus: " << mus << "\n";);
@ -78,34 +76,35 @@ namespace sat {
set_core();
return l_undef;
}
if (minimize_partial && 3*delta_time > core.size() && core.size() < mus.size()) {
break;
}
unsigned num_literals = core.size() + mus.size();
if (num_literals <= 2) {
// IF_VERBOSE(0, verbose_stream() << "num literals: " << core << " " << mus << "\n";);
break;
}
if (s.m_config.m_core_minimize_partial && s.m_stats.m_restart - m_restart > m_max_restarts) {
IF_VERBOSE(1, verbose_stream() << "(sat restart budget exceeded)\n";);
set_core();
return l_true;
}
literal lit = core.back();
core.pop_back();
lbool is_sat;
{
flet<unsigned> _restart_bound(s.m_config.m_restart_max, m_max_num_restarts);
scoped_append _sa(mus, core);
mus.push_back(~lit);
is_sat = s.check(mus.size(), mus.c_ptr());
TRACE("sat", tout << "mus: " << mus << "\n";);
}
IF_VERBOSE(1, verbose_stream() << "(sat.mus " << is_sat << ")\n";);
switch (is_sat) {
case l_undef:
core.push_back(lit);
set_core();
return l_undef;
if (!s.canceled()) {
// treat restart max as sat, so literal is in the mus
mus.push_back(lit);
}
else {
core.push_back(lit);
set_core();
return l_undef;
}
break;
case l_true: {
SASSERT(value_at(lit, s.get_model()) == l_false);
mus.push_back(lit);
@ -115,11 +114,9 @@ namespace sat {
case l_false:
literal_vector const& new_core = s.get_core();
if (new_core.contains(~lit)) {
IF_VERBOSE(3, verbose_stream() << "miss core " << lit << "\n";);
++core_miss;
IF_VERBOSE(3, verbose_stream() << "(sat.mus unit reduction, literal is in both cores " << lit << ")\n";);
}
else {
core_miss = 0;
TRACE("sat", tout << "core: " << new_core << " mus: " << mus << "\n";);
core.reset();
for (unsigned i = 0; i < new_core.size(); ++i) {
@ -131,14 +128,6 @@ namespace sat {
}
break;
}
unsigned new_num_literals = core.size() + mus.size();
if (new_num_literals == num_literals) {
delta_time++;
}
else {
delta_time = 0;
}
}
set_core();
IF_VERBOSE(3, verbose_stream() << "(sat.mus.new " << s.m_core << ")\n";);
@ -159,13 +148,9 @@ namespace sat {
lbool mus::qx(literal_set& assignment, literal_set& support, bool has_support) {
lbool is_sat = l_true;
if (s.m_config.m_core_minimize_partial && s.m_stats.m_restart - m_restart > m_max_restarts) {
IF_VERBOSE(1, verbose_stream() << "(sat restart budget exceeded)\n";);
return l_true;
}
if (has_support) {
scoped_append _sa(m_mus, support.to_vector());
is_sat = s.check(m_mus.size(), m_mus.c_ptr());
is_sat = s.check(m_mus.size(), m_mus.c_ptr());
switch (is_sat) {
case l_false: {
literal_set core(s.get_core());
@ -173,7 +158,7 @@ namespace sat {
assignment.reset();
return l_true;
}
case l_undef:
case l_undef:
return l_undef;
case l_true:
update_model();

3
src/sat/sat_mus.h
View file

@ -26,8 +26,7 @@ namespace sat {
literal_vector m_mus;
bool m_is_active;
model m_model; // model obtained during minimal unsat core
unsigned m_restart;
unsigned m_max_restarts;
unsigned m_max_num_restarts;
public:

45
src/sat/sat_par.cpp Normal file
View file

@ -0,0 +1,45 @@
/*++
Copyright (c) 2017 Microsoft Corporation
Module Name:
sat_par.cpp
Abstract:
Utilities for parallel SAT solving.
Author:
Nikolaj Bjorner (nbjorner) 2017-1-29.
Revision History:
--*/
#include "sat_par.h"
namespace sat {
par::par() {}
void par::exchange(literal_vector const& in, unsigned& limit, literal_vector& out) {
#pragma omp critical (par_solver)
{
if (limit < m_units.size()) {
// this might repeat some literals.
out.append(m_units.size() - limit, m_units.c_ptr() + limit);
}
for (unsigned i = 0; i < in.size(); ++i) {
literal lit = in[i];
if (!m_unit_set.contains(lit.index())) {
m_unit_set.insert(lit.index());
m_units.push_back(lit);
}
}
limit = m_units.size();
}
}
};

39
src/sat/sat_par.h Normal file
View file

@ -0,0 +1,39 @@
/*++
Copyright (c) 2017 Microsoft Corporation
Module Name:
sat_par.h
Abstract:
Utilities for parallel SAT solving.
Author:
Nikolaj Bjorner (nbjorner) 2017-1-29.
Revision History:
--*/
#ifndef SAT_PAR_H_
#define SAT_PAR_H_
#include"sat_types.h"
#include"hashtable.h"
#include"map.h"
namespace sat {
class par {
typedef hashtable<unsigned, u_hash, u_eq> index_set;
literal_vector m_units;
index_set m_unit_set;
public:
par();
void exchange(literal_vector const& in, unsigned& limit, literal_vector& out);
};
};
#endif

1
src/sat/sat_params.pyg
View file

@ -22,4 +22,5 @@ def_module_params('sat',
('dyn_sub_res', BOOL, True, 'dynamic subsumption resolution for minimizing learned clauses'),
('core.minimize', BOOL, False, 'minimize computed core'),
('core.minimize_partial', BOOL, False, 'apply partial (cheap) core minimization'),
('parallel_threads', UINT, 1, 'number of parallel threads to use'),
('dimacs.core', BOOL, False, 'extract core from DIMACS benchmarks')))

25
src/sat/sat_simplifier.cpp
View file

@ -896,7 +896,7 @@ namespace sat {
unsigned idx = l.index();
if (m_queue.contains(idx))
m_queue.decreased(idx);
else
else
m_queue.insert(idx);
}
literal next() { SASSERT(!empty()); return to_literal(m_queue.erase_min()); }
@ -918,16 +918,19 @@ namespace sat {
}
void insert(literal l) {
bool_var v = l.var();
if (s.is_external(v) || s.was_eliminated(v))
return;
m_queue.insert(l);
}
bool process_var(bool_var v) {
return !s.is_external(v) && !s.was_eliminated(v);
}
void operator()(unsigned num_vars) {
for (bool_var v = 0; v < num_vars; v++) {
insert(literal(v, false));
insert(literal(v, true));
if (process_var(v)) {
insert(literal(v, false));
insert(literal(v, true));
}
}
while (!m_queue.empty()) {
s.checkpoint();
@ -941,9 +944,9 @@ namespace sat {
void process(literal l) {
TRACE("blocked_clause", tout << "processing: " << l << "\n";);
model_converter::entry * new_entry = 0;
if (s.is_external(l.var()) || s.was_eliminated(l.var()))
if (!process_var(l.var())) {
return;
}
{
m_to_remove.reset();
{
@ -963,8 +966,10 @@ namespace sat {
mc.insert(*new_entry, c);
unsigned sz = c.size();
for (unsigned i = 0; i < sz; i++) {
if (c[i] != l)
m_queue.decreased(~c[i]);
literal lit = c[i];
if (lit != l && process_var(lit.var())) {
m_queue.decreased(~lit);
}
}
}
s.unmark_all(c);

146
src/sat/sat_solver.cpp
View file

@ -35,6 +35,7 @@ namespace sat {
m_rlimit(l),
m_config(p),
m_ext(ext),
m_par(0),
m_cleaner(*this),
m_simplifier(*this, p),
m_scc(*this, p),
@ -72,6 +73,8 @@ namespace sat {
void solver::copy(solver const & src) {
SASSERT(m_mc.empty() && src.m_mc.empty());
SASSERT(scope_lvl() == 0);
SASSERT(src.scope_lvl() == 0);
// create new vars
if (num_vars() < src.num_vars()) {
for (bool_var v = num_vars(); v < src.num_vars(); v++) {
@ -81,19 +84,25 @@ namespace sat {
VERIFY(v == mk_var(ext, dvar));
}
}
unsigned sz = src.scope_lvl() == 0 ? src.m_trail.size() : src.m_scopes[0].m_trail_lim;
for (unsigned i = 0; i < sz; ++i) {
assign(src.m_trail[i], justification());
}
{
// copy binary clauses
vector<watch_list>::const_iterator it = src.m_watches.begin();
vector<watch_list>::const_iterator end = src.m_watches.begin();
for (unsigned l_idx = 0; it != end; ++it, ++l_idx) {
watch_list const & wlist = *it;
unsigned sz = src.m_watches.size();
for (unsigned l_idx = 0; l_idx < sz; ++l_idx) {
literal l = ~to_literal(l_idx);
watch_list::const_iterator it2 = wlist.begin();
watch_list::const_iterator end2 = wlist.end();
for (; it2 != end2; ++it2) {
if (!it2->is_binary_non_learned_clause())
watch_list const & wlist = src.m_watches[l_idx];
watch_list::const_iterator it = wlist.begin();
watch_list::const_iterator end = wlist.end();
for (; it != end; ++it) {
if (!it->is_binary_non_learned_clause())
continue;
literal l2 = it->get_literal();
if (l.index() > l2.index())
continue;
literal l2 = it2->get_literal();
mk_clause_core(l, l2);
}
}
@ -711,6 +720,9 @@ namespace sat {
pop_to_base_level();
IF_VERBOSE(2, verbose_stream() << "(sat.sat-solver)\n";);
SASSERT(scope_lvl() == 0);
if (m_config.m_num_parallel > 0 && !m_par) {
return check_par(num_lits, lits);
}
#ifdef CLONE_BEFORE_SOLVING
if (m_mc.empty()) {
m_clone = alloc(solver, m_params, 0 /* do not clone extension */);
@ -759,6 +771,7 @@ namespace sat {
restart();
simplify_problem();
exchange_par();
if (check_inconsistent()) return l_false;
gc();
@ -774,6 +787,121 @@ namespace sat {
}
}
enum par_exception_kind {
DEFAULT_EX,
ERROR_EX
};
lbool solver::check_par(unsigned num_lits, literal const* lits) {
int num_threads = static_cast<int>(m_config.m_num_parallel);
scoped_limits scoped_rlimit(rlimit());
vector<reslimit> rlims(num_threads);
ptr_vector<sat::solver> solvers(num_threads);
sat::par par;
for (int i = 0; i < num_threads; ++i) {
m_params.set_uint("random_seed", i);
solvers[i] = alloc(sat::solver, m_params, rlims[i], 0);
solvers[i]->copy(*this);
solvers[i]->set_par(&par);
scoped_rlimit.push_child(&solvers[i]->rlimit());
}
int finished_id = -1;
std::string ex_msg;
par_exception_kind ex_kind;
unsigned error_code = 0;
lbool result = l_undef;
#pragma omp parallel for
for (int i = 0; i < num_threads; ++i) {
try {
lbool r = solvers[i]->check(num_lits, lits);
bool first = false;
#pragma omp critical (par_solver)
{
if (finished_id == UINT_MAX) {
finished_id = i;
first = true;
result = r;
}
}
if (first) {
if (r == l_true) {
set_model(solvers[i]->get_model());
}
else if (r == l_false) {
m_core.reset();
m_core.append(solvers[i]->get_core());
}
for (int j = 0; j < num_threads; ++j) {
if (i != j) {
rlims[j].cancel();
}
}
}
}
catch (z3_error & err) {
if (i == 0) {
error_code = err.error_code();
ex_kind = ERROR_EX;
}
}
catch (z3_exception & ex) {
if (i == 0) {
ex_msg = ex.msg();
ex_kind = DEFAULT_EX;
}
}
}
for (int i = 0; i < num_threads; ++i) {
dealloc(solvers[i]);
}
if (finished_id == -1) {
switch (ex_kind) {
case ERROR_EX: throw z3_error(error_code);
default: throw default_exception(ex_msg.c_str());
}
}
return result;
}
/*
\brief import lemmas/units from parallel sat solvers.
*/
void solver::exchange_par() {
if (m_par && scope_lvl() == 0) {
unsigned num_in = 0, num_out = 0;
SASSERT(scope_lvl() == 0); // parallel with assumptions is TBD
literal_vector in, out;
for (unsigned i = m_par_limit_out; i < m_trail.size(); ++i) {
literal lit = m_trail[i];
if (lit.var() < m_par_num_vars) {
++num_out;
out.push_back(lit);
}
}
m_par_limit_out = m_trail.size();
m_par->exchange(out, m_par_limit_in, in);
for (unsigned i = 0; !inconsistent() && i < in.size(); ++i) {
literal lit = in[i];
SASSERT(lit.var() < m_par_num_vars);
if (lvl(lit.var()) != 0 || value(lit) != l_true) {
++num_in;
assign(lit, justification());
}
}
if (num_in > 0 || num_out > 0) {
IF_VERBOSE(1, verbose_stream() << "(sat-sync out: " << num_out << " in: " << num_in << ")\n";);
}
}
}
void solver::set_par(par* p) {
m_par = p;
m_par_num_vars = num_vars();
m_par_limit_in = 0;
m_par_limit_out = 0;
}
bool_var solver::next_var() {
bool_var next;

11
src/sat/sat_solver.h
View file

@ -33,6 +33,7 @@ Revision History:
#include"sat_iff3_finder.h"
#include"sat_probing.h"
#include"sat_mus.h"
#include"sat_par.h"
#include"params.h"
#include"statistics.h"
#include"stopwatch.h"
@ -74,6 +75,7 @@ namespace sat {
config m_config;
stats m_stats;
extension * m_ext;
par* m_par;
random_gen m_rand;
clause_allocator m_cls_allocator;
cleaner m_cleaner;
@ -128,6 +130,10 @@ namespace sat {
literal_set m_assumption_set; // set of enabled assumptions
literal_vector m_core; // unsat core
unsigned m_par_limit_in;
unsigned m_par_limit_out;
unsigned m_par_num_vars;
void del_clauses(clause * const * begin, clause * const * end);
friend class integrity_checker;
@ -209,6 +215,7 @@ namespace sat {
bool inconsistent() const { return m_inconsistent; }
unsigned num_vars() const { return m_level.size(); }
unsigned num_clauses() const;
unsigned num_restarts() const { return m_restarts; }
bool is_external(bool_var v) const { return m_external[v] != 0; }
bool was_eliminated(bool_var v) const { return m_eliminated[v] != 0; }
unsigned scope_lvl() const { return m_scope_lvl; }
@ -240,7 +247,9 @@ namespace sat {
m_num_checkpoints = 0;
if (memory::get_allocation_size() > m_config.m_max_memory) throw solver_exception(Z3_MAX_MEMORY_MSG);
}
void set_par(par* p);
bool canceled() { return !m_rlimit.inc(); }
config const& get_config() { return m_config; }
typedef std::pair<literal, literal> bin_clause;
protected:
watch_list & get_wlist(literal l) { return m_watches[l.index()]; }
@ -316,6 +325,8 @@ namespace sat {
bool check_model(model const & m) const;
void restart();
void sort_watch_lits();
void exchange_par();
lbool check_par(unsigned num_lits, literal const* lits);
// -----------------------
//

3
src/sat/sat_solver/inc_sat_solver.cpp
View file

@ -140,6 +140,7 @@ public:
if (r != l_true) return r;
r = m_solver.check(m_asms.size(), m_asms.c_ptr());
switch (r) {
case l_true:
if (sz > 0) {
@ -276,6 +277,8 @@ public:
return r;
}
virtual lbool find_mutexes(expr_ref_vector const& vars, vector<expr_ref_vector>& mutexes) {
sat::literal_vector ls;
u_map<expr*> lit2var;