mirror of
https://github.com/Z3Prover/z3
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122 lines
4.2 KiB
C++
122 lines
4.2 KiB
C++
/*++
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Copyright (c) 2021 Microsoft Corporation
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Module Name:
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Conflict explanation using forbidden intervals as described in
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"Solving bitvectors with MCSAT: explanations from bits and pieces"
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by S. Graham-Lengrand, D. Jovanovic, B. Dutertre.
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Author:
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Nikolaj Bjorner (nbjorner) 2021-03-19
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Jakob Rath 2021-04-06
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--*/
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#pragma once
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#include "sat/smt/polysat/types.h"
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#include "sat/smt/polysat/interval.h"
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#include "sat/smt/polysat/constraints.h"
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namespace polysat {
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class core;
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struct fi_record {
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eval_interval interval;
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vector<signed_constraint> side_cond;
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vector<signed_constraint> src; // only units may have multiple src (as they can consist of contracted bit constraints)
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rational coeff;
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unsigned bit_width = 0; // number of lower bits; TODO: should move this to viable::entry; where the coeff/bit-width is adapted accordingly
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/** Create invalid fi_record */
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fi_record(): interval(eval_interval::full()) {}
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void reset() {
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interval = eval_interval::full();
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side_cond.reset();
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src.reset();
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coeff.reset();
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bit_width = 0;
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}
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struct less {
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bool operator()(fi_record const& a, fi_record const& b) const {
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return a.interval.lo_val() < b.interval.lo_val();
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}
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};
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};
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class forbidden_intervals {
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void push_eq(bool is_trivial, pdd const& p, vector<signed_constraint>& side_cond);
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eval_interval to_interval(signed_constraint const& c, bool is_trivial, rational& coeff,
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rational & lo_val, pdd & lo, rational & hi_val, pdd & hi);
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std::tuple<bool, rational, pdd, pdd> linear_decompose(pvar v, pdd const& p, vector<signed_constraint>& out_side_cond);
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bool match_linear1(signed_constraint const& c,
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rational const& a1, pdd const& b1, pdd const& e1,
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rational const& a2, pdd const& b2, pdd const& e2,
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fi_record& fi);
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bool match_linear2(signed_constraint const& c,
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rational const & a1, pdd const& b1, pdd const& e1,
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rational const & a2, pdd const& b2, pdd const& e2,
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fi_record& fi);
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bool match_linear3(signed_constraint const& c,
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rational const & a1, pdd const& b1, pdd const& e1,
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rational const & a2, pdd const& b2, pdd const& e2,
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fi_record& fi);
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bool match_linear4(signed_constraint const& c,
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rational const & a1, pdd const& b1, pdd const& e1,
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rational const & a2, pdd const& b2, pdd const& e2,
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fi_record& fi);
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void add_non_unit_side_conds(fi_record& fi, pdd const& b1, pdd const& e1, pdd const& b2, pdd const& e2);
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bool match_zero(signed_constraint const& c,
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rational const & a1, pdd const& b1, pdd const& e1,
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rational const & a2, pdd const& b2, pdd const& e2,
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fi_record& fi);
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bool match_max(signed_constraint const& c,
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rational const & a1, pdd const& b1, pdd const& e1,
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rational const & a2, pdd const& b2, pdd const& e2,
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fi_record& fi);
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bool match_non_zero(signed_constraint const& c,
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rational const& a1, pdd const& b1, pdd const& e1,
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pdd const& q,
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fi_record& fi);
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bool match_non_max(signed_constraint const& c,
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pdd const& p,
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rational const& a2, pdd const& b2, pdd const& e2,
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fi_record& fi);
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bool get_interval_ule(signed_constraint const& c, pvar v, fi_record& fi);
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bool get_interval_umul_ovfl(signed_constraint const& c, pvar v, fi_record& fi);
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struct backtrack {
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bool released = false;
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vector<signed_constraint>& side_cond;
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unsigned sz;
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backtrack(vector<signed_constraint>& s):side_cond(s), sz(s.size()) {}
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~backtrack() {
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if (!released)
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side_cond.shrink(sz);
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}
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};
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core& s;
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public:
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forbidden_intervals(core& s): s(s) {}
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bool get_interval(signed_constraint const& c, pvar v, fi_record& fi);
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};
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}
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