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/******************************************************************************
* Top contributors (to current version):
* Liana Hadarean, Aina Niemetz, Andrew Reynolds
*
* This file is part of the cvc5 project.
*
* Copyright (c) 2009-2021 by the authors listed in the file AUTHORS
* in the top-level source directory and their institutional affiliations.
* All rights reserved. See the file COPYING in the top-level source
* directory for licensing information.
* ****************************************************************************
*
* Algebraic solver.
*/
#include "theory/bv/bv_subtheory_inequality.h"
#include "options/smt_options.h"
#include "smt/smt_statistics_registry.h"
#include "theory/bv/bv_solver_lazy.h"
#include "theory/bv/theory_bv_utils.h"
#include "theory/rewriter.h"
#include "theory/theory_model.h"
using namespace std;
using namespace cvc5;
using namespace cvc5::context;
using namespace cvc5::theory;
using namespace cvc5::theory::bv;
using namespace cvc5::theory::bv::utils;
bool InequalitySolver::check(Theory::Effort e) {
Debug("bv-subtheory-inequality") << "InequalitySolveR::check("<< e <<")\n";
TimerStat::CodeTimer inequalityTimer(d_statistics.d_solveTime);
++(d_statistics.d_numCallstoCheck);
d_bv->spendResource(Resource::TheoryCheckStep);
bool ok = true;
while (!done() && ok) {
TNode fact = get();
Debug("bv-subtheory-inequality") << " "<< fact <<"\n";
if (fact.getKind() == kind::EQUAL) {
TNode a = fact[0];
if( a.getType().isBitVector() ){
TNode b = fact[1];
ok = addInequality(a, b, false, fact);
if (ok)
ok = addInequality(b, a, false, fact);
}
} else if (fact.getKind() == kind::NOT && fact[0].getKind() == kind::EQUAL) {
TNode a = fact[0][0];
if( a.getType().isBitVector() ){
TNode b = fact[0][1];
ok = d_inequalityGraph.addDisequality(a, b, fact);
}
}
if (fact.getKind() == kind::NOT && fact[0].getKind() == kind::BITVECTOR_ULE) {
TNode a = fact[0][1];
TNode b = fact[0][0];
ok = addInequality(a, b, true, fact);
// propagate
// NodeManager *nm = NodeManager::currentNM();
// if (d_bv->isSharedTerm(a) && d_bv->isSharedTerm(b)) {
// Node neq = nm->mkNode(kind::NOT, nm->mkNode(kind::EQUAL, a, b));
// d_bv->storePropagation(neq, SUB_INEQUALITY);
// d_explanations[neq] = fact;
// }
} else if (fact.getKind() == kind::NOT && fact[0].getKind() == kind::BITVECTOR_ULT) {
TNode a = fact[0][1];
TNode b = fact[0][0];
ok = addInequality(a, b, false, fact);
} else if (fact.getKind() == kind::BITVECTOR_ULT) {
TNode a = fact[0];
TNode b = fact[1];
ok = addInequality(a, b, true, fact);
// propagate
// if (d_bv->isSharedTerm(a) && d_bv->isSharedTerm(b)) {
// Node neq = nm->mkNode(kind::NOT, nm->mkNode(kind::EQUAL, a, b));
// d_bv->storePropagation(neq, SUB_INEQUALITY);
// d_explanations[neq] = fact;
// }
} else if (fact.getKind() == kind::BITVECTOR_ULE) {
TNode a = fact[0];
TNode b = fact[1];
ok = addInequality(a, b, false, fact);
}
}
if (!ok) {
std::vector<TNode> conflict;
d_inequalityGraph.getConflict(conflict);
Node confl = utils::flattenAnd(conflict);
d_bv->setConflict(confl);
Debug("bv-subtheory-inequality") << "InequalitySolver::conflict: "<< confl <<"\n";
return false;
}
if (isComplete() && Theory::fullEffort(e)) {
// make sure all the disequalities we didn't split on are still satisifed
// and split on the ones that are not
std::vector<Node> lemmas;
d_inequalityGraph.checkDisequalities(lemmas);
for(unsigned i = 0; i < lemmas.size(); ++i) {
d_bv->lemma(lemmas[i]);
}
}
Debug("bv-subtheory-inequality") << "InequalitySolver done. ";
return true;
}
EqualityStatus InequalitySolver::getEqualityStatus(TNode a, TNode b)
{
if (!isComplete()) return EQUALITY_UNKNOWN;
NodeManager* nm = NodeManager::currentNM();
Node a_lt_b = nm->mkNode(kind::BITVECTOR_ULT, a, b);
Node b_lt_a = nm->mkNode(kind::BITVECTOR_ULT, b, a);
// if an inequality containing the terms has been asserted then we know
// the equality is false
if (d_assertionSet.contains(a_lt_b) || d_assertionSet.contains(b_lt_a))
{
return EQUALITY_FALSE;
}
if (!d_inequalityGraph.hasValueInModel(a)
|| !d_inequalityGraph.hasValueInModel(b))
{
return EQUALITY_UNKNOWN;
}
// TODO: check if this disequality is entailed by inequalities via
// transitivity
BitVector a_val = d_inequalityGraph.getValueInModel(a);
BitVector b_val = d_inequalityGraph.getValueInModel(b);
if (a_val == b_val)
{
return EQUALITY_TRUE_IN_MODEL;
}
else
{
return EQUALITY_FALSE_IN_MODEL;
}
}
void InequalitySolver::assertFact(TNode fact) {
d_assertionQueue.push_back(fact);
d_assertionSet.insert(fact);
if (!isInequalityOnly(fact)) {
d_isComplete = false;
}
}
bool InequalitySolver::isInequalityOnly(TNode node) {
if (node.getKind() == kind::NOT) {
node = node[0];
}
if (node.getAttribute(IneqOnlyComputedAttribute())) {
return node.getAttribute(IneqOnlyAttribute());
}
if (node.getKind() != kind::EQUAL &&
node.getKind() != kind::BITVECTOR_ULT &&
node.getKind() != kind::BITVECTOR_ULE &&
node.getKind() != kind::CONST_BITVECTOR &&
node.getKind() != kind::SELECT &&
node.getKind() != kind::STORE &&
node.getMetaKind() != kind::metakind::VARIABLE) {
// not worth caching
return false;
}
bool res = true;
for (unsigned i = 0; res && i < node.getNumChildren(); ++i) {
res = res && isInequalityOnly(node[i]);
}
node.setAttribute(IneqOnlyComputedAttribute(), true);
node.setAttribute(IneqOnlyAttribute(), res);
return res;
}
void InequalitySolver::explain(TNode literal, std::vector<TNode>& assumptions) {
Assert(d_explanations.find(literal) != d_explanations.end());
TNode explanation = d_explanations[literal];
assumptions.push_back(explanation);
Debug("bv-inequality-explain") << "InequalitySolver::explain " << literal << " with " << explanation <<"\n";
}
void InequalitySolver::propagate(Theory::Effort e) { Assert(false); }
bool InequalitySolver::collectModelValues(TheoryModel* m,
const std::set<Node>& termSet)
{
Debug("bitvector-model") << "InequalitySolver::collectModelValues \n";
std::vector<Node> model;
d_inequalityGraph.getAllValuesInModel(model);
for (unsigned i = 0; i < model.size(); ++i) {
Assert(model[i].getKind() == kind::EQUAL);
if (!m->assertEquality(model[i][0], model[i][1], true))
{
return false;
}
}
return true;
}
Node InequalitySolver::getModelValue(TNode var) {
Assert(isInequalityOnly(var));
Debug("bitvector-model") << "InequalitySolver::getModelValue (" << var <<")";
Assert(isComplete());
Node result = Node();
if (!d_inequalityGraph.hasValueInModel(var)) {
Assert(d_bv->isSharedTerm(var));
} else {
BitVector val = d_inequalityGraph.getValueInModel(var);
result = utils::mkConst(val);
}
Debug("bitvector-model") << " => " << result <<"\n";
return result;
}
void InequalitySolver::preRegister(TNode node) {
Kind kind = node.getKind();
if (kind == kind::EQUAL ||
kind == kind::BITVECTOR_ULE ||
kind == kind::BITVECTOR_ULT) {
d_ineqTerms.insert(node[0]);
d_ineqTerms.insert(node[1]);
}
}
bool InequalitySolver::addInequality(TNode a, TNode b, bool strict, TNode fact)
{
bool ok = d_inequalityGraph.addInequality(a, b, strict, fact);
if (!ok || !strict) return ok;
Node one = utils::mkConst(utils::getSize(a), 1);
Node a_plus_one = Rewriter::rewrite(
NodeManager::currentNM()->mkNode(kind::BITVECTOR_PLUS, a, one));
if (d_ineqTerms.find(a_plus_one) != d_ineqTerms.end())
{
ok = d_inequalityGraph.addInequality(a_plus_one, b, false, fact);
}
return ok;
}
InequalitySolver::Statistics::Statistics()
: d_numCallstoCheck(smtStatisticsRegistry().registerInt(
"theory::bv::inequality::NumCallsToCheck")),
d_solveTime(smtStatisticsRegistry().registerTimer(
"theory::bv::inequality::SolveTime"))
{
}
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