z3-z3-4.12.6.src.sat.sat_xor_finder.h Maven / Gradle / Ivy
/*++
Copyright (c) 2020 Microsoft Corporation
Module Name:
sat_xor_finder.h
Abstract:
xor finder
Author:
Nikolaj Bjorner 2020-01-02
Notes:
Based on xor extraction paper by Meel & Soos, AAAI 2018.
--*/
#pragma once
#include "util/params.h"
#include "util/statistics.h"
#include "sat/sat_clause.h"
#include "sat/sat_types.h"
#include "sat/sat_solver.h"
namespace sat {
class xor_finder {
solver& s;
struct clause_filter {
unsigned m_filter;
clause* m_clause;
clause_filter(unsigned f, clause* cp):
m_filter(f), m_clause(cp) {}
};
unsigned m_max_xor_size;
vector> m_clause_filters; // index of clauses.
unsigned m_combination; // bit-mask of parities that have been found
vector m_parity; // lookup parity for clauses
clause_vector m_clauses_to_remove; // remove clauses that become xors
unsigned_vector m_var_position; // position of var in main clause
literal_vector m_clause; // reference clause with literals sorted according to main clause
unsigned_vector m_missing; // set of indices not occurring in clause.
clause_vector m_removed_clauses;
std::function m_on_xor;
void set_combination(unsigned mask);
inline bool get_combination(unsigned mask) const { return (m_combination & (1 << mask)) != 0; }
void extract_xor(clause& c);
void add_xor(bool parity, clause& c);
bool extract_xor(bool parity, clause& c, literal l1, literal l2);
bool extract_xor(bool parity, clause& c, clause& c2);
bool update_combinations(clause& c, bool parity, unsigned mask);
void init_parity();
void init_clause_filter();
void init_clause_filter(clause_vector& clauses);
unsigned get_clause_filter(clause& c);
public:
xor_finder(solver& s) : s(s), m_max_xor_size(5) { init_parity(); }
void set(std::function& f) { m_on_xor = f; }
bool parity(unsigned i, unsigned j) const { return m_parity[i][j]; }
unsigned max_xor_size() const { return m_max_xor_size; }
void operator()(clause_vector& clauses);
clause_vector const& removed_clauses() const { return m_removed_clauses; }
};
}