replacer.cpp

/*****************************************************************************
Copyright (C) 2016  Security Research Labs
Copyright (C) 2018  Mate Soos, Davin Choo, Kian Ming A. Chai, DSO National Laboratories

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***********************************************/

#include "replacer.hpp"
#include <iostream>
#include <fstream>
#include "anf.hpp"

using std::cout;
using std::endl;

using namespace BLib;

bool Replacer::evaluate(const vector<lbool>& vals) const
{
    bool ret = true;
    size_t num = 0;
    for (vector<lbool>::const_iterator it = value.begin(), end = value.end();
         it != end; it++, num++) {
        if (*it == l_Undef)
            continue;

        assert(vals.size() >= num);
        ret &= (vals[num] == *it);
    }

    num = 0;
    for (vector<Lit>::const_iterator it = replaceTable.begin(),
                                     end = replaceTable.end();
         it != end; it++, num++) {
        if (num == it->var())
            continue;

        assert(vals.size() >= it->var());
        assert(vals.size() >= num);
        lbool one = vals[it->var()] ^ it->sign();
        lbool other = vals[num];
        ret &= (one == other);
    }

    return ret;
}

/*
 * Suppose monomial is a*b*c and we want to replace:
 *   a with 1+d
 *   b with e
 *   c with 1+f
 * (Note: e may be b itself)
 *
 * init   : ret = 1
 * after a: ret = (d) + (1)
 *              = d + 1
 * after b: ret = e*d + e
 * after c: ret = (f*e*d + f*e) + (e*d + e)
 *              = f*e*d + f*e + e*d + e
 *              = (1+d)*(e)*(1+f)
 *              = a*b*c
 */
BoolePolynomial Replacer::update(const BooleMonomial& m) const
{
    BoolePolynomial ret(true, m.ring());

    for (const uint32_t v : m) {
        if (value[v] != l_Undef) {
            if (value[v] == l_True)
                continue;
            else
                return BoolePolynomial(m.ring());
        }

        assert(replaceTable.size() > v); //Variable must exist
        const Lit lit = replaceTable[v];

        BoolePolynomial alsoAdd(m.ring());
        if (lit.sign())
            alsoAdd = ret;
        ret *= BooleVariable(lit.var(), m.ring());
        ret += alsoAdd;
    }

    return ret;
}

BoolePolynomial Replacer::update(const BoolePolynomial& eq) const
{
    BoolePolynomial ret = BoolePolynomial(eq.ring());
    for (const BooleMonomial& mono : eq) {
        ret += update(mono);
    }
    return ret;
}

bool Replacer::willUpdate(const BoolePolynomial& eq) const
{
    for (const uint32_t v : eq.usedVariables()) {
        if (value[v] != l_Undef)
            return true;
        if (replaceTable[v] != Lit(v, false))
            return true;
    }
    return false;
}

vector<uint32_t> Replacer::setValue(uint32_t var, bool val)
{
    vector<uint32_t> alsoUpdated;
    alsoUpdated.push_back(var);

    //update to representative
    if (replaceTable[var] != Lit(var, false)) {
        val ^= replaceTable[var].sign();
        var = replaceTable[var].var();
    }
    alsoUpdated.push_back(var);

    //set value
    if (value[var] != l_Undef) {
        if (value[var] != boolToLBool(val)) {
            ok = false;
        }
        return alsoUpdated;
    }

    value[var] = boolToLBool(val);

    //update anti/equivalent variables
    map<uint32_t, vector<uint32_t> >::iterator it = revReplaceTable.find(var);
    if (it == revReplaceTable.end()) {
        return alsoUpdated;
    }

    vector<uint32_t>& vars = it->second;
    for (vector<uint32_t>::iterator it2 = vars.begin(), end2 = vars.end();
         it2 != end2; it2++) {
        assert(replaceTable[*it2].var() == var);
        value[*it2] = boolToLBool(replaceTable[*it2].sign() ^ val);
        alsoUpdated.push_back(*it2);
    }

    return alsoUpdated;
}

vector<uint32_t> Replacer::setReplace(uint32_t var, Lit lit)
{
    assert(var < replaceTable.size());
    assert(lit.var() < replaceTable.size());

    vector<uint32_t> ret;

    //if value is set somewhere, set it
    if (value[var] != l_Undef) {
        return setValue(lit.var(), (value[var] ^ lit.sign()) == l_True);
    }

    if (value[lit.var()] != l_Undef) {
        return setValue(var, (value[lit.var()] ^ lit.sign()) == l_True);
    }

    //move forward
    lit ^= replaceTable[var].sign();
    var = replaceTable[var].var();
    lit = replaceTable[lit.var()] ^ lit.sign();
    ret.push_back(lit.var());
    ret.push_back(var);

    //they are already replaced with each other
    if (lit.var() == var) {
        //..but invertedly, so UNSAT
        if (lit.sign())
            ok = false;
        return ret;
    }

    //lit.var() is not the head of a replace group
    if (revReplaceTable.find(lit.var()) == revReplaceTable.end()) {
        replaceTable[lit.var()] = Lit(var, lit.sign());
        revReplaceTable[var].push_back(lit.var());

        //These may have been updated
        for (vector<uint32_t>::const_iterator it = revReplaceTable[var].begin(),
                                              end = revReplaceTable[var].end();
             it != end; it++) {
            ret.push_back(*it);
        }
        return ret;
    }

    //var is not the head of a replace group
    if (revReplaceTable.find(var) == revReplaceTable.end()) {
        replaceTable[var] = lit;
        revReplaceTable[lit.var()].push_back(var);

        //These may have been updated
        for (vector<uint32_t>::const_iterator
                 it = revReplaceTable[lit.var()].begin(),
                 end = revReplaceTable[lit.var()].end();
             it != end; it++) {
            ret.push_back(*it);
        }

        return ret;
    }

    //both are dependent, move lit's dependencies under var
    assert(revReplaceTable.find(lit.var()) != revReplaceTable.end());
    assert(revReplaceTable.find(var) != revReplaceTable.end());

    vector<uint32_t>& vars = revReplaceTable[lit.var()];
    for (vector<uint32_t>::iterator it = vars.begin(), end = vars.end();
         it != end; it++) {
        revReplaceTable[var].push_back(*it);
        replaceTable[*it] = Lit(var, replaceTable[*it].sign() ^ lit.sign());
        ret.push_back(*it);
    }
    revReplaceTable.erase(revReplaceTable.find(lit.var()));
    replaceTable[lit.var()] = Lit(var, lit.sign());
    revReplaceTable[var].push_back(lit.var());

    //These may have been updated
    for (vector<uint32_t>::const_iterator it = revReplaceTable[var].begin(),
                                          end = revReplaceTable[var].end();
         it != end; it++) {
        ret.push_back(*it);
    }

    return ret;
}

void Replacer::print_solution_map(std::ofstream* ofs)
{
    uint32_t num = 0;
    for (vector<lbool>::const_iterator it = value.begin(), end = value.end();
         it != end; it++, num++) {
        if (*it != l_Undef) {
            (*ofs) << "ANF-var-val " << num << " = " << *it << endl;
        }
    }

    num = 0;
    for (vector<Lit>::const_iterator it = replaceTable.begin(), end = replaceTable.end();
        it != end; it++, num++
    ) {
        //it is not replaced
        if (it->var() == num)
            continue;

        //maybe never solved for, because equation is "a = b", and neither "a", nor "b" appear anywhere else
        //so, just set the value randomly... to true :)
        (*ofs) << "must-set-ANF-var-to-any " << it->var() << endl;
        (*ofs) << "ANF-var " << num << " = "
               << "ANF-var " << it->var() << " ^ " << it->sign() << endl;
    }
}

set<size_t> Replacer::get_proj_map(const set<size_t>& vars) const {
    set<size_t> ret;
    for(const auto& v: vars) {
        if (value[v] != l_Undef) continue;
        Lit l;
        l = replaceTable[v];
        if (value[l.var()] != l_Undef) continue;
        ret.insert(l.var());
    }
    return ret;
}

void Replacer::get_solution_map(map<uint32_t, VarMap>& ret) const
{
    uint32_t num = 0;
    for (vector<lbool>::const_iterator it = value.begin(), end = value.end();
         it != end; it++, num++) {
        if (*it != l_Undef) {
            VarMap m;
            m.type = Bosph::VarMap::fixed;
            m.value = (*it == l_True);
            ret[num] = m;
        }
    }

    num = 0;
    for (vector<Lit>::const_iterator it = replaceTable.begin(), end = replaceTable.end();
        it != end; it++, num++
    ) {
        //it is not replaced
        if (it->var() == num)
            continue;

        //Don't overwrite existing value with this
        if (ret.find(it->var()) == ret.end()) {
            VarMap m;
            m.type = Bosph::VarMap::must_set;
            ret[it->var()] = m;
        }

        VarMap m2;
        m2.type = Bosph::VarMap::anf_repl;
        m2.other_var = it->var();
        m2.inv = it->sign();
        ret[num] = m2;
    }

}

vector<lbool> Replacer::extendSolution(const vector<lbool>& solution) const
{
    assert(solution.size() <= value.size());
    vector<lbool> sol2(solution);
    sol2.resize(value.size(), l_Undef);

    //add stored solutions
    assert(sol2.size() == value.size());
    size_t num = 0;
    for (vector<lbool>::const_iterator it = value.begin(), end = value.end();
         it != end; it++, num++) {
        if (sol2[num] != l_Undef && *it != l_Undef) {
            if (sol2[num] != *it) {
                cout << "Solved solution and solution stored by replacer "
                        "differ!\n";
                exit(-1);
            }
            continue;
        }

        if (*it != l_Undef) {
            sol2[num] = *it;
        }
    }

    //Add replaced variables
    assert(sol2.size() == replaceTable.size());
    num = 0;
    for (vector<Lit>::const_iterator it = replaceTable.begin(),
                                     end = replaceTable.end();
         it != end; it++, num++) {
        //uint32_t is not replaced
        if (it->var() == num)
            continue;

        //maybe never solved for, because equation is "a = b", and neither "a", nor "b" appear anywhere else
        //so, just set the value randomly... to true :)
        if (sol2[it->var()] == l_Undef)
            sol2[it->var()] = l_True;

        const lbool val = sol2[it->var()] ^ it->sign();
        if (sol2[num] != l_Undef && sol2[num] != val) {
            cout << "num:" << num << " var:" << it->var()
                 << "sign: " << (int)it->sign() << endl;
            cout << "sol2[num]: " << sol2[num]
                 << " sol2[it->var()]:" << sol2[it->var()] << endl;
            cout << "Solved replaced solution and stored solution differ!"
                 << endl;
            exit(-1);
        }
        sol2[num] = val;
    }

    return sol2;
}

bool Replacer::isReplaced(const uint32_t var) const
{
    return getReplaced(var).var() != var;
}