z3/src/ast/sls/sls_bv_plugin.cpp

/*++
Copyright (c) 2024 Microsoft Corporation

Module Name:

    sls_bv_plugin.cpp

Abstract:

    Theory plugin for bit-vector local search

Author:

    Nikolaj Bjorner (nbjorner) 2024-07-06

--*/
#include "ast/sls/sls_bv_plugin.h"
#include "ast/ast_ll_pp.h"
#include "ast/ast_pp.h"

namespace sls {

    bv_plugin::bv_plugin(context& ctx): 
        plugin(ctx),
        bv(m),
        m_terms(ctx),
        m_eval(m_terms, ctx) {
        m_fid = bv.get_family_id();
    }

    void bv_plugin::register_term(expr* e) {
        m_terms.register_term(e);
        m_eval.register_term(e);
    }
    
    expr_ref bv_plugin::get_value(expr* e) {
        SASSERT(bv.is_bv(e));
        auto const & val = m_eval.wval(e);
        return expr_ref(bv.mk_numeral(val.get_value(), e->get_sort()), m);
    }

    bool bv_plugin::is_bv_predicate(expr* e) {
        return m_terms.is_bv_predicate(e);
    }

    void bv_plugin::start_propagation() {
        m_eval.start_propagation();
    }

    void bv_plugin::propagate_literal(sat::literal lit) {       
        SASSERT(ctx.is_true(lit));
        auto e = ctx.atom(lit.var());
        if (!is_bv_predicate(e))
            return;
        auto a = to_app(e);

        if (!m_eval.eval_is_correct(a)) {
            TRACE("sls", tout << "incorrect eval " << lit << ": " << mk_bounded_pp(e, m) << "\n";);
            IF_VERBOSE(20, verbose_stream() << "repair " << lit << " " << mk_bounded_pp(e, m) << "\n");
            ctx.new_value_eh(e);
        }
    }

    bool bv_plugin::propagate() {
        auto& axioms = m_terms.axioms();
        if (!axioms.empty()) {
            for (auto* e : axioms)
                ctx.add_constraint(e);
            axioms.reset();
            return true;
        }
        return false;
    }

    void bv_plugin::initialize() {
        if (!m_initialized) {
            m_eval.init();
            m_initialized = true;
        }
    }

    bool bv_plugin::is_sat() {
        bool is_sat = true;
        for (auto t : ctx.subterms())
            if (is_app(t) && bv.is_bv(t) && to_app(t)->get_family_id() == bv.get_fid() && !m_eval.eval_is_correct(to_app(t))) {
                TRACE("sls", tout << "incorrect eval: " << mk_bounded_pp(t, m) << " " << m_eval.wval(t) << "\n";);
                ctx.new_value_eh(t);
                is_sat = false;
            }
        return is_sat;
    }
    
    std::ostream& bv_plugin::display(std::ostream& out) const {
        return m_eval.display(out);
    }
    
    bool bv_plugin::set_value(expr* e, expr* v) {
        if (!bv.is_bv(e))
            return false;
        rational val;
        VERIFY(bv.is_numeral(v, val));
        auto& w = m_eval.eval(to_app(e));
        w.set_value(w.eval, val);
        return w.commit_eval_check_tabu();
    }

    bool bv_plugin::repair_down(app* e) {
        unsigned n = e->get_num_args();
        bool status = true;
        if (n == 0 || m_eval.is_uninterpreted(e) || m_eval.eval_is_correct(e)) 
            goto done;
        
        if (n == 2) {
            auto d1 = get_depth(e->get_arg(0));
            auto d2 = get_depth(e->get_arg(1));
            unsigned s = ctx.rand(d1 + d2 + 2);
            if (s <= d1 && m_eval.repair_down(e, 0)) 
                goto done;
            
            if (m_eval.repair_down(e, 1)) 
                goto done;
            
            if (m_eval.repair_down(e, 0)) 
                goto done;
        }
        else {
            unsigned s = ctx.rand(n);
            for (unsigned i = 0; i < n; ++i) {
                auto j = (i + s) % n;
                if (m_eval.repair_down(e, j)) 
                    goto done;
            }
        }
        status = false;
        
    done:
        log(e, false, status);
        return status;
    }

    void bv_plugin::repair_up(app* e) {
        if (m_eval.repair_up(e)) {
            IF_VERBOSE(0,
                if (!m_eval.eval_is_correct(e))
                    verbose_stream() << "Incorrect eval #" << e->get_id() << " " << mk_bounded_pp(e, m) << "\n";
                    );
            log(e, true, true);
            SASSERT(m_eval.eval_is_correct(e));
            if (m.is_bool(e)) {
                if (ctx.is_true(e) != m_eval.bval1(e))
                    ctx.flip(ctx.atom2bool_var(e));
            }
        }
        else 
            log(e, true, false);

    }

    void bv_plugin::repair_literal(sat::literal lit) {
        SASSERT(ctx.is_true(lit));
        auto e = ctx.atom(lit.var());
        if (!is_bv_predicate(e))
            return;
        auto a = to_app(e);
        if (!m_eval.eval_is_correct(a))
            ctx.flip(lit.var());
    }

    void bv_plugin::collect_statistics(statistics& st) const {
        m_eval.collect_statistics(st);
    }

    std::ostream& bv_plugin::trace_repair(bool down, expr* e) {
        verbose_stream() << (down ? "d #" : "u #")
            << e->get_id() << ": "
            << mk_bounded_pp(e, m, 1) << " ";
        return m_eval.display_value(verbose_stream(), e) << "\n";
    }

    void bv_plugin::trace() {
        IF_VERBOSE(2, verbose_stream()
            << "(bvsls :restarts " << m_stats.m_restarts << ")\n");
    }

    void bv_plugin::log(expr* e, bool up_down, bool success) {
        IF_VERBOSE(11, verbose_stream() << mk_bounded_pp(e, m) << " " << (up_down?"u":"d") << " " << (success ? "S" : "F");
                   if (bv.is_bv(e)) verbose_stream() << " " << m_eval.wval(e);
                   verbose_stream() << "\n");
    }

}