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/********************* */
/*! \file kissat.cpp
** \verbatim
** Top contributors (to current version):
** Aina Niemetz
** This file is part of the CVC4 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.\endverbatim
**
** \brief Wrapper for Kissat SAT Solver.
**
** Wrapper for the Kissat SAT solver (for theory of bit-vectors).
**/
#include "prop/kissat.h"
#ifdef CVC4_USE_KISSAT
#include "base/check.h"
namespace cvc5 {
namespace prop {
using KissatLit = int32_t;
using KissatVar = int32_t;
// helper functions
namespace {
SatValue toSatValue(int32_t result)
{
if (result == 10) return SAT_VALUE_TRUE;
if (result == 20) return SAT_VALUE_FALSE;
Assert(result == 0);
return SAT_VALUE_UNKNOWN;
}
/**
* Helper to convert the value of a literal as returned by Kissat to the
* corresponding true/false SAT_VALUE.
* Note: Kissat returns lit/-lit for true/false. Older versions returned 1/-1.
*/
SatValue toSatValueLit(int value)
{
if (value > 0) return SAT_VALUE_TRUE;
Assert(value < 0);
return SAT_VALUE_FALSE;
}
/** Helper to convert SatLiteral to KissatLit. */
KissatLit toKissatLit(const SatLiteral lit)
{
return lit.isNegated() ? -lit.getSatVariable() : lit.getSatVariable();
}
/** Helper to convert a SatVariable to a KissatVar. */
KissatVar toKissatVar(SatVariable var) { return var; }
} // namespace
KissatSolver::KissatSolver(StatisticsRegistry* registry,
const std::string& name)
: d_solver(kissat_init()),
// Note: Kissat variables start with index 1 rather than 0 since negated
// literals are represented as the negation of the index.
d_nextVarIdx(1),
d_statistics(registry, name)
{
}
void KissatSolver::init()
{
d_true = newVar();
d_false = newVar();
kissat_add(d_solver, toKissatVar(d_true));
kissat_add(d_solver, 0);
kissat_add(d_solver, -toKissatVar(d_false));
kissat_add(d_solver, 0);
}
KissatSolver::~KissatSolver() { kissat_release(d_solver); }
ClauseId KissatSolver::addClause(SatClause& clause, bool removable)
{
for (const SatLiteral& lit : clause)
{
kissat_add(d_solver, toKissatLit(lit));
}
kissat_add(d_solver, 0);
++d_statistics.d_numClauses;
return ClauseIdError;
}
ClauseId KissatSolver::addXorClause(SatClause& clause, bool rhs, bool removable)
{
Unreachable() << "Kissat does not support adding XOR clauses.";
}
SatVariable KissatSolver::newVar(bool isTheoryAtom,
bool preRegister,
bool canErase)
{
++d_statistics.d_numVariables;
return d_nextVarIdx++;
}
SatVariable KissatSolver::trueVar() { return d_true; }
SatVariable KissatSolver::falseVar() { return d_false; }
SatValue KissatSolver::solve()
{
TimerStat::CodeTimer codeTimer(d_statistics.d_solveTime);
SatValue res = toSatValue(kissat_solve(d_solver));
d_okay = (res == SAT_VALUE_TRUE);
++d_statistics.d_numSatCalls;
return res;
}
SatValue KissatSolver::solve(long unsigned int&)
{
Unimplemented() << "Setting limits for Kissat not supported yet";
};
SatValue KissatSolver::solve(const std::vector<SatLiteral>& assumptions)
{
Unimplemented() << "Incremental solving with Kissat not supported yet";
}
void KissatSolver::interrupt() { kissat_terminate(d_solver); }
SatValue KissatSolver::value(SatLiteral l)
{
Assert(d_okay);
return toSatValueLit(kissat_value(d_solver, toKissatLit(l)));
}
SatValue KissatSolver::modelValue(SatLiteral l)
{
Assert(d_okay);
return value(l);
}
unsigned KissatSolver::getAssertionLevel() const
{
Unreachable() << "Kissat does not support assertion levels.";
}
bool KissatSolver::ok() const { return d_okay; }
KissatSolver::Statistics::Statistics(StatisticsRegistry* registry,
const std::string& prefix)
: d_registry(registry),
d_numSatCalls("theory::bv::" + prefix + "::Kissat::calls_to_solve", 0),
d_numVariables("theory::bv::" + prefix + "::Kissat::variables", 0),
d_numClauses("theory::bv::" + prefix + "::Kissat::clauses", 0),
d_solveTime("theory::bv::" + prefix + "::Kissat::solve_time")
{
d_registry->registerStat(&d_numSatCalls);
d_registry->registerStat(&d_numVariables);
d_registry->registerStat(&d_numClauses);
d_registry->registerStat(&d_solveTime);
}
KissatSolver::Statistics::~Statistics()
{
d_registry->unregisterStat(&d_numSatCalls);
d_registry->unregisterStat(&d_numVariables);
d_registry->unregisterStat(&d_numClauses);
d_registry->unregisterStat(&d_solveTime);
}
} // namespace prop
} // namespace cvc5
#endif // CVC4_USE_KISSAT
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