mirror of
https://github.com/Z3Prover/z3
synced 2025-04-07 18:05:21 +00:00
429 lines
15 KiB
C++
429 lines
15 KiB
C++
/*++
|
|
Copyright (c) 2011 Microsoft Corporation
|
|
|
|
Module Name:
|
|
|
|
sat_solver.h
|
|
|
|
Abstract:
|
|
|
|
SAT solver main class.
|
|
|
|
Author:
|
|
|
|
Leonardo de Moura (leonardo) 2011-05-21.
|
|
|
|
Revision History:
|
|
|
|
--*/
|
|
#ifndef _SAT_SOLVER_H_
|
|
#define _SAT_SOLVER_H_
|
|
|
|
#include"sat_types.h"
|
|
#include"sat_clause.h"
|
|
#include"sat_watched.h"
|
|
#include"sat_justification.h"
|
|
#include"sat_var_queue.h"
|
|
#include"sat_extension.h"
|
|
#include"sat_config.h"
|
|
#include"sat_cleaner.h"
|
|
#include"sat_simplifier.h"
|
|
#include"sat_scc.h"
|
|
#include"sat_asymm_branch.h"
|
|
#include"sat_iff3_finder.h"
|
|
#include"sat_probing.h"
|
|
#include"params.h"
|
|
#include"statistics.h"
|
|
#include"stopwatch.h"
|
|
#include"trace.h"
|
|
|
|
namespace sat {
|
|
|
|
/**
|
|
\brief Main statistic counters.
|
|
*/
|
|
struct stats {
|
|
unsigned m_mk_var;
|
|
unsigned m_mk_bin_clause;
|
|
unsigned m_mk_ter_clause;
|
|
unsigned m_mk_clause;
|
|
unsigned m_conflict;
|
|
unsigned m_propagate;
|
|
unsigned m_bin_propagate;
|
|
unsigned m_ter_propagate;
|
|
unsigned m_decision;
|
|
unsigned m_restart;
|
|
unsigned m_gc_clause;
|
|
unsigned m_del_clause;
|
|
unsigned m_minimized_lits;
|
|
unsigned m_dyn_sub_res;
|
|
stats() { reset(); }
|
|
void reset();
|
|
void collect_statistics(statistics & st) const;
|
|
};
|
|
|
|
class solver {
|
|
public:
|
|
struct abort_solver {};
|
|
protected:
|
|
volatile bool m_cancel;
|
|
config m_config;
|
|
stats m_stats;
|
|
extension * m_ext;
|
|
random_gen m_rand;
|
|
clause_allocator m_cls_allocator;
|
|
cleaner m_cleaner;
|
|
model m_model;
|
|
model_converter m_mc;
|
|
simplifier m_simplifier;
|
|
scc m_scc;
|
|
asymm_branch m_asymm_branch;
|
|
probing m_probing;
|
|
bool m_inconsistent;
|
|
// A conflict is usually a single justification. That is, a justification
|
|
// for false. If m_not_l is not null_literal, then m_conflict is a
|
|
// justification for l, and the conflict is union of m_no_l and m_conflict;
|
|
justification m_conflict;
|
|
literal m_not_l;
|
|
clause_vector m_clauses;
|
|
clause_vector m_learned;
|
|
unsigned m_num_frozen;
|
|
vector<watch_list> m_watches;
|
|
svector<lbool> m_assignment;
|
|
svector<justification> m_justification;
|
|
svector<char> m_decision;
|
|
svector<char> m_mark;
|
|
svector<char> m_lit_mark;
|
|
svector<char> m_eliminated;
|
|
svector<char> m_external;
|
|
svector<unsigned> m_level;
|
|
svector<unsigned> m_activity;
|
|
unsigned m_activity_inc;
|
|
svector<char> m_phase;
|
|
svector<char> m_prev_phase;
|
|
svector<char> m_assigned_since_gc;
|
|
bool m_phase_cache_on;
|
|
unsigned m_phase_counter;
|
|
var_queue m_case_split_queue;
|
|
unsigned m_qhead;
|
|
unsigned m_scope_lvl;
|
|
literal_vector m_trail;
|
|
clause_wrapper_vector m_clauses_to_reinit;
|
|
struct scope {
|
|
unsigned m_trail_lim;
|
|
unsigned m_clauses_to_reinit_lim;
|
|
bool m_inconsistent;
|
|
};
|
|
svector<scope> m_scopes;
|
|
stopwatch m_stopwatch;
|
|
params_ref m_params;
|
|
scoped_ptr<solver> m_clone; // for debugging purposes
|
|
|
|
void del_clauses(clause * const * begin, clause * const * end);
|
|
|
|
friend class integrity_checker;
|
|
friend class cleaner;
|
|
friend class simplifier;
|
|
friend class scc;
|
|
friend class elim_eqs;
|
|
friend class asymm_branch;
|
|
friend class probing;
|
|
friend class iff3_finder;
|
|
friend struct mk_stat;
|
|
public:
|
|
solver(params_ref const & p, extension * ext);
|
|
~solver();
|
|
|
|
// -----------------------
|
|
//
|
|
// Misc
|
|
//
|
|
// -----------------------
|
|
void updt_params(params_ref const & p);
|
|
static void collect_param_descrs(param_descrs & d);
|
|
|
|
void set_cancel(bool f);
|
|
void collect_statistics(statistics & st);
|
|
void reset_statistics();
|
|
void display_status(std::ostream & out) const;
|
|
|
|
/**
|
|
\brief Copy (non learned) clauses from src to this solver.
|
|
Create missing variables if needed.
|
|
|
|
\pre the model converter of src and this must be empty
|
|
*/
|
|
void copy(solver const & src);
|
|
|
|
// -----------------------
|
|
//
|
|
// Variable & Clause creation
|
|
//
|
|
// -----------------------
|
|
bool_var mk_var(bool ext = false, bool dvar = true);
|
|
void mk_clause(unsigned num_lits, literal * lits);
|
|
void mk_clause(literal l1, literal l2);
|
|
void mk_clause(literal l1, literal l2, literal l3);
|
|
|
|
protected:
|
|
void del_clause(clause & c) { m_cls_allocator.del_clause(&c); m_stats.m_del_clause++; }
|
|
clause * mk_clause_core(unsigned num_lits, literal * lits, bool learned);
|
|
void mk_bin_clause(literal l1, literal l2, bool learned);
|
|
bool propagate_bin_clause(literal l1, literal l2);
|
|
clause * mk_ter_clause(literal * lits, bool learned);
|
|
void attach_ter_clause(clause & c, bool & reinit);
|
|
void attach_ter_clause(clause & c) { bool reinit; attach_ter_clause(c, reinit); }
|
|
clause * mk_nary_clause(unsigned num_lits, literal * lits, bool learned);
|
|
void attach_nary_clause(clause & c, bool & reinit);
|
|
void attach_nary_clause(clause & c) { bool reinit; attach_nary_clause(c, reinit); }
|
|
void attach_clause(clause & c, bool & reinit);
|
|
void attach_clause(clause & c) { bool reinit; attach_clause(c, reinit); }
|
|
unsigned select_watch_lit(clause const & cls, unsigned starting_at) const;
|
|
unsigned select_learned_watch_lit(clause const & cls) const;
|
|
bool simplify_clause(unsigned & num_lits, literal * lits) const;
|
|
template<bool lvl0>
|
|
bool simplify_clause_core(unsigned & num_lits, literal * lits) const;
|
|
void dettach_bin_clause(literal l1, literal l2, bool learned);
|
|
void dettach_clause(clause & c);
|
|
void dettach_nary_clause(clause & c);
|
|
void dettach_ter_clause(clause & c);
|
|
void push_reinit_stack(clause & c);
|
|
|
|
// -----------------------
|
|
//
|
|
// Basic
|
|
//
|
|
// -----------------------
|
|
public:
|
|
bool inconsistent() const { return m_inconsistent; }
|
|
unsigned num_vars() const { return m_level.size(); }
|
|
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; }
|
|
lbool value(literal l) const { return m_assignment[l.index()]; }
|
|
lbool value(bool_var v) const { return m_assignment[literal(v, false).index()]; }
|
|
unsigned lvl(bool_var v) const { return m_level[v]; }
|
|
unsigned lvl(literal l) const { return m_level[l.var()]; }
|
|
void assign(literal l, justification j) {
|
|
TRACE("sat_assign", tout << l << " previous value: " << value(l) << "\n";);
|
|
switch (value(l)) {
|
|
case l_false: set_conflict(j, ~l); break;
|
|
case l_undef: assign_core(l, j); break;
|
|
case l_true: return;
|
|
}
|
|
}
|
|
void assign_core(literal l, justification jst);
|
|
void set_conflict(justification c, literal not_l);
|
|
void set_conflict(justification c) { set_conflict(c, null_literal); }
|
|
lbool status(clause const & c) const;
|
|
clause_offset get_offset(clause const & c) const { return m_cls_allocator.get_offset(&c); }
|
|
void checkpoint() {
|
|
if (m_cancel) throw solver_exception(TACTIC_CANCELED_MSG);
|
|
if (memory::get_allocation_size() > m_config.m_max_memory) throw solver_exception(TACTIC_MAX_MEMORY_MSG);
|
|
}
|
|
protected:
|
|
watch_list & get_wlist(literal l) { return m_watches[l.index()]; }
|
|
watch_list const & get_wlist(literal l) const { return m_watches[l.index()]; }
|
|
watch_list & get_wlist(unsigned l_idx) { return m_watches[l_idx]; }
|
|
bool is_marked(bool_var v) const { return m_mark[v] != 0; }
|
|
void mark(bool_var v) { SASSERT(!is_marked(v)); m_mark[v] = true; }
|
|
void reset_mark(bool_var v) { SASSERT(is_marked(v)); m_mark[v] = false; }
|
|
bool is_marked_lit(literal l) const { return m_lit_mark[l.index()] != 0; }
|
|
void mark_lit(literal l) { SASSERT(!is_marked_lit(l)); m_lit_mark[l.index()] = true; }
|
|
void unmark_lit(literal l) { SASSERT(is_marked_lit(l)); m_lit_mark[l.index()] = false; }
|
|
|
|
// -----------------------
|
|
//
|
|
// Propagation
|
|
//
|
|
// -----------------------
|
|
public:
|
|
// if update == true, then glue of learned clauses is updated.
|
|
bool propagate(bool update);
|
|
|
|
protected:
|
|
bool propagate_core(bool update);
|
|
|
|
// -----------------------
|
|
//
|
|
// Search
|
|
//
|
|
// -----------------------
|
|
public:
|
|
lbool check();
|
|
model const & get_model() const { return m_model; }
|
|
model_converter const & get_model_converter() const { return m_mc; }
|
|
|
|
protected:
|
|
unsigned m_conflicts;
|
|
unsigned m_conflicts_since_restart;
|
|
unsigned m_restart_threshold;
|
|
unsigned m_luby_idx;
|
|
unsigned m_conflicts_since_gc;
|
|
unsigned m_gc_threshold;
|
|
double m_min_d_tk;
|
|
unsigned m_next_simplify;
|
|
bool decide();
|
|
bool_var next_var();
|
|
lbool bounded_search();
|
|
void init_search();
|
|
void simplify_problem();
|
|
void mk_model();
|
|
bool check_model(model const & m) const;
|
|
void restart();
|
|
void sort_watch_lits();
|
|
|
|
// -----------------------
|
|
//
|
|
// GC
|
|
//
|
|
// -----------------------
|
|
protected:
|
|
void gc();
|
|
void gc_glue();
|
|
void gc_psm();
|
|
void gc_glue_psm();
|
|
void gc_psm_glue();
|
|
void save_psm();
|
|
void gc_half(char const * st_name);
|
|
void gc_dyn_psm();
|
|
bool activate_frozen_clause(clause & c);
|
|
unsigned psm(clause const & c) const;
|
|
bool can_delete(clause const & c) const {
|
|
if (c.on_reinit_stack())
|
|
return false;
|
|
if (c.size() == 3)
|
|
return true; // not needed to justify anything.
|
|
literal l0 = c[0];
|
|
if (value(l0) != l_true)
|
|
return true;
|
|
justification const & jst = m_justification[l0.var()];
|
|
return !jst.is_clause() || m_cls_allocator.get_clause(jst.get_clause_offset()) != &c;
|
|
}
|
|
|
|
// -----------------------
|
|
//
|
|
// Conflict resolution
|
|
//
|
|
// -----------------------
|
|
protected:
|
|
unsigned m_conflict_lvl;
|
|
literal_vector m_lemma;
|
|
literal_vector m_ext_antecedents;
|
|
bool resolve_conflict();
|
|
bool resolve_conflict_core();
|
|
unsigned get_max_lvl(literal consequent, justification js);
|
|
void process_antecedent(literal antecedent, unsigned & num_marks);
|
|
void fill_ext_antecedents(literal consequent, justification js);
|
|
unsigned skip_literals_above_conflict_level();
|
|
void forget_phase_of_vars(unsigned from_lvl);
|
|
void updt_phase_counters();
|
|
svector<char> m_diff_levels;
|
|
unsigned num_diff_levels(unsigned num, literal const * lits);
|
|
|
|
// lemma minimization
|
|
typedef approx_set_tpl<unsigned, u2u, unsigned> level_approx_set;
|
|
bool_var_vector m_unmark;
|
|
level_approx_set m_lvl_set;
|
|
bool_var_vector m_lemma_min_stack;
|
|
bool process_antecedent_for_minimization(literal antecedent);
|
|
bool implied_by_marked(literal lit);
|
|
void reset_unmark(unsigned old_size);
|
|
void updt_lemma_lvl_set();
|
|
void minimize_lemma();
|
|
void reset_lemma_var_marks();
|
|
void dyn_sub_res();
|
|
|
|
// -----------------------
|
|
//
|
|
// Backtracking
|
|
//
|
|
// -----------------------
|
|
public:
|
|
void push();
|
|
void pop(unsigned num_scopes);
|
|
|
|
protected:
|
|
void unassign_vars(unsigned old_sz);
|
|
void reinit_clauses(unsigned old_sz);
|
|
|
|
// -----------------------
|
|
//
|
|
// Simplification
|
|
//
|
|
// -----------------------
|
|
public:
|
|
void cleanup();
|
|
void simplify(bool learned = true);
|
|
void asymmetric_branching();
|
|
unsigned scc_bin();
|
|
|
|
// -----------------------
|
|
//
|
|
// Activity related stuff
|
|
//
|
|
// -----------------------
|
|
public:
|
|
void inc_activity(bool_var v) {
|
|
unsigned & act = m_activity[v];
|
|
act += m_activity_inc;
|
|
m_case_split_queue.activity_increased_eh(v);
|
|
if (act > (1 << 24))
|
|
rescale_activity();
|
|
}
|
|
|
|
void decay_activity() {
|
|
m_activity_inc *= 11;
|
|
m_activity_inc /= 10;
|
|
}
|
|
|
|
private:
|
|
void rescale_activity();
|
|
|
|
// -----------------------
|
|
//
|
|
// Iterators
|
|
//
|
|
// -----------------------
|
|
public:
|
|
clause * const * begin_clauses() const { return m_clauses.begin(); }
|
|
clause * const * end_clauses() const { return m_clauses.end(); }
|
|
clause * const * begin_learned() const { return m_learned.begin(); }
|
|
clause * const * end_learned() const { return m_learned.end(); }
|
|
typedef std::pair<literal, literal> bin_clause;
|
|
void collect_bin_clauses(svector<bin_clause> & r, bool learned) const;
|
|
|
|
// -----------------------
|
|
//
|
|
// Debugging
|
|
//
|
|
// -----------------------
|
|
public:
|
|
bool check_invariant() const;
|
|
void display(std::ostream & out) const;
|
|
void display_watches(std::ostream & out) const;
|
|
void display_dimacs(std::ostream & out) const;
|
|
|
|
protected:
|
|
void display_binary(std::ostream & out) const;
|
|
void display_units(std::ostream & out) const;
|
|
void display_assignment(std::ostream & out) const;
|
|
unsigned num_clauses() const;
|
|
bool is_unit(clause const & c) const;
|
|
bool is_empty(clause const & c) const;
|
|
bool check_missed_propagation(clause_vector const & cs) const;
|
|
bool check_missed_propagation() const;
|
|
bool check_marks() const;
|
|
};
|
|
|
|
struct mk_stat {
|
|
solver const & m_solver;
|
|
mk_stat(solver const & s):m_solver(s) {}
|
|
void display(std::ostream & out) const;
|
|
};
|
|
|
|
std::ostream & operator<<(std::ostream & out, mk_stat const & stat);
|
|
};
|
|
|
|
#endif
|