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/********************* */
/*! \file eager_bitblaster.cpp
** \verbatim
** Original author: Liana Hadarean
** Major contributors: none
** Minor contributors (to current version): none
** This file is part of the CVC4 project.
** Copyright (c) 2009-2014 New York University and The University of Iowa
** See the file COPYING in the top-level source directory for licensing
** information.\endverbatim
**
** \brief
**
** Bitblaster for the eager bv solver.
**/
#include "cvc4_private.h"
#include "theory/bv/bitblaster_template.h"
#include "theory/bv/options.h"
#include "theory/theory_model.h"
#include "theory/bv/theory_bv.h"
#include "prop/cnf_stream.h"
#include "prop/sat_solver_factory.h"
using namespace CVC4;
using namespace CVC4::theory;
using namespace CVC4::theory::bv;
void BitblastingRegistrar::preRegister(Node n) {
d_bitblaster->bbAtom(n);
};
EagerBitblaster::EagerBitblaster(TheoryBV* theory_bv)
: TBitblaster<Node>()
, d_bv(theory_bv)
, d_bbAtoms()
, d_variables()
{
d_bitblastingRegistrar = new BitblastingRegistrar(this);
d_nullContext = new context::Context();
d_satSolver = prop::SatSolverFactory::createMinisat(d_nullContext, "EagerBitblaster");
d_cnfStream = new prop::TseitinCnfStream(d_satSolver, d_bitblastingRegistrar, d_nullContext);
MinisatEmptyNotify* notify = new MinisatEmptyNotify();
d_satSolver->setNotify(notify);
}
EagerBitblaster::~EagerBitblaster() {
delete d_cnfStream;
delete d_satSolver;
delete d_nullContext;
delete d_bitblastingRegistrar;
}
void EagerBitblaster::bbFormula(TNode node) {
d_cnfStream->convertAndAssert(node, false, false);
}
/**
* Bitblasts the atom, assigns it a marker literal, adding it to the SAT solver
* NOTE: duplicate clauses are not detected because of marker literal
* @param node the atom to be bitblasted
*
*/
void EagerBitblaster::bbAtom(TNode node) {
node = node.getKind() == kind::NOT? node[0] : node;
if (node.getKind() == kind::BITVECTOR_BITOF)
return;
if (hasBBAtom(node)) {
return;
}
Debug("bitvector-bitblast") << "Bitblasting node " << node <<"\n";
// the bitblasted definition of the atom
Node normalized = Rewriter::rewrite(node);
Node atom_bb = normalized.getKind() != kind::CONST_BOOLEAN ?
Rewriter::rewrite(d_atomBBStrategies[normalized.getKind()](normalized, this)) :
normalized;
// asserting that the atom is true iff the definition holds
Node atom_definition = utils::mkNode(kind::IFF, node, atom_bb);
AlwaysAssert (options::bitblastMode() == theory::bv::BITBLAST_MODE_EAGER);
storeBBAtom(node, atom_definition);
d_cnfStream->convertAndAssert(atom_definition, false, false);
}
void EagerBitblaster::storeBBAtom(TNode atom, Node atom_bb) {
// no need to store the definition for the lazy bit-blaster
d_bbAtoms.insert(atom);
}
bool EagerBitblaster::hasBBAtom(TNode atom) const {
return d_bbAtoms.find(atom) != d_bbAtoms.end();
}
void EagerBitblaster::bbTerm(TNode node, Bits& bits) {
if (hasBBTerm(node)) {
getBBTerm(node, bits);
return;
}
Debug("bitvector-bitblast") << "Bitblasting node " << node <<"\n";
d_termBBStrategies[node.getKind()] (node, bits, this);
Assert (bits.size() == utils::getSize(node));
storeBBTerm(node, bits);
}
void EagerBitblaster::makeVariable(TNode var, Bits& bits) {
Assert(bits.size() == 0);
for (unsigned i = 0; i < utils::getSize(var); ++i) {
bits.push_back(utils::mkBitOf(var, i));
}
d_variables.insert(var);
}
Node EagerBitblaster::getBBAtom(TNode node) const {
return node;
}
/**
* Calls the solve method for the Sat Solver.
*
* @return true for sat, and false for unsat
*/
bool EagerBitblaster::solve() {
if (Trace.isOn("bitvector")) {
Trace("bitvector") << "EagerBitblaster::solve(). \n";
}
Debug("bitvector") << "EagerBitblaster::solve(). \n";
// TODO: clear some memory
// if (something) {
// NodeManager* nm= NodeManager::currentNM();
// Rewriter::garbageCollect();
// nm->reclaimZombiesUntil(options::zombieHuntThreshold());
// }
return prop::SAT_VALUE_TRUE == d_satSolver->solve();
}
/**
* Returns the value a is currently assigned to in the SAT solver
* or null if the value is completely unassigned.
*
* @param a
* @param fullModel whether to create a "full model," i.e., add
* constants to equivalence classes that don't already have them
*
* @return
*/
Node EagerBitblaster::getVarValue(TNode a, bool fullModel) {
if (!hasBBTerm(a)) {
Assert(isSharedTerm(a));
return Node();
}
Bits bits;
getBBTerm(a, bits);
Integer value(0);
for (int i = bits.size() -1; i >= 0; --i) {
prop::SatValue bit_value;
if (d_cnfStream->hasLiteral(bits[i])) {
prop::SatLiteral bit = d_cnfStream->getLiteral(bits[i]);
bit_value = d_satSolver->value(bit);
Assert (bit_value != prop::SAT_VALUE_UNKNOWN);
} else {
// the bit is unconstrainted so we can give it an arbitrary value
bit_value = prop::SAT_VALUE_FALSE;
}
Integer bit_int = bit_value == prop::SAT_VALUE_TRUE ? Integer(1) : Integer(0);
value = value * 2 + bit_int;
}
return utils::mkConst(BitVector(bits.size(), value));
}
void EagerBitblaster::collectModelInfo(TheoryModel* m, bool fullModel) {
TNodeSet::const_iterator it = d_variables.begin();
for (; it!= d_variables.end(); ++it) {
TNode var = *it;
if (Theory::theoryOf(var) == theory::THEORY_BV || isSharedTerm(var)) {
Node const_value = getVarValue(var, fullModel);
if(const_value == Node()) {
if( fullModel ){
// if the value is unassigned just set it to zero
const_value = utils::mkConst(BitVector(utils::getSize(var), 0u));
}
}
if(const_value != Node()) {
Debug("bitvector-model") << "TLazyBitblaster::collectModelInfo (assert (= "
<< var << " "
<< const_value << "))\n";
m->assertEquality(var, const_value, true);
}
}
}
}
bool EagerBitblaster::isSharedTerm(TNode node) {
return d_bv->d_sharedTermsSet.find(node) != d_bv->d_sharedTermsSet.end();
}
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