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/******************************************************************************
* Top contributors (to current version):
* Aina Niemetz, Tim King, 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.
* ****************************************************************************
*
* ITE simplification preprocessing pass.
*/
#include "preprocessing/passes/ite_simp.h"
#include <vector>
#include "options/smt_options.h"
#include "preprocessing/assertion_pipeline.h"
#include "preprocessing/preprocessing_pass_context.h"
#include "smt/smt_statistics_registry.h"
#include "smt_util/nary_builder.h"
#include "theory/arith/arith_ite_utils.h"
#include "theory/rewriter.h"
#include "theory/theory_engine.h"
using namespace std;
using namespace cvc5;
using namespace cvc5::theory;
namespace cvc5 {
namespace preprocessing {
namespace passes {
/* -------------------------------------------------------------------------- */
namespace {
Node simpITE(util::ITEUtilities* ite_utils, TNode assertion)
{
if (!ite_utils->containsTermITE(assertion))
{
return assertion;
}
else
{
Node result = ite_utils->simpITE(assertion);
Node res_rewritten = Rewriter::rewrite(result);
if (options::simplifyWithCareEnabled())
{
Chat() << "starting simplifyWithCare()" << endl;
Node postSimpWithCare = ite_utils->simplifyWithCare(res_rewritten);
Chat() << "ending simplifyWithCare()"
<< " post simplifyWithCare()" << postSimpWithCare.getId() << endl;
result = Rewriter::rewrite(postSimpWithCare);
}
else
{
result = res_rewritten;
}
return result;
}
}
/**
* Ensures the assertions asserted after index 'before' now effectively come
* before 'real_assertions_end'.
*/
void compressBeforeRealAssertions(AssertionPipeline* assertionsToPreprocess,
size_t before)
{
size_t cur_size = assertionsToPreprocess->size();
if (before >= cur_size || assertionsToPreprocess->getRealAssertionsEnd() <= 0
|| assertionsToPreprocess->getRealAssertionsEnd() >= cur_size)
{
return;
}
// assertions
// original: [0 ... assertionsToPreprocess.getRealAssertionsEnd())
// can be modified
// ites skolems [assertionsToPreprocess.getRealAssertionsEnd(), before)
// cannot be moved
// added [before, cur_size)
// can be modified
Assert(0 < assertionsToPreprocess->getRealAssertionsEnd());
Assert(assertionsToPreprocess->getRealAssertionsEnd() <= before);
Assert(before < cur_size);
std::vector<Node> intoConjunction;
for (size_t i = before; i < cur_size; ++i)
{
intoConjunction.push_back((*assertionsToPreprocess)[i]);
}
assertionsToPreprocess->resize(before);
size_t lastBeforeItes = assertionsToPreprocess->getRealAssertionsEnd() - 1;
intoConjunction.push_back((*assertionsToPreprocess)[lastBeforeItes]);
Node newLast = cvc5::util::NaryBuilder::mkAssoc(kind::AND, intoConjunction);
assertionsToPreprocess->replace(lastBeforeItes, newLast);
Assert(assertionsToPreprocess->size() == before);
}
} // namespace
/* -------------------------------------------------------------------------- */
ITESimp::Statistics::Statistics()
: d_arithSubstitutionsAdded(smtStatisticsRegistry().registerInt(
"preprocessing::passes::ITESimp::ArithSubstitutionsAdded"))
{
}
bool ITESimp::doneSimpITE(AssertionPipeline* assertionsToPreprocess)
{
bool result = true;
bool simpDidALotOfWork = d_iteUtilities.simpIteDidALotOfWorkHeuristic();
if (simpDidALotOfWork)
{
if (options::compressItes())
{
result = d_iteUtilities.compress(assertionsToPreprocess);
}
if (result)
{
// if false, don't bother to reclaim memory here.
NodeManager* nm = NodeManager::currentNM();
if (nm->poolSize() >= options::zombieHuntThreshold())
{
Chat() << "..ite simplifier did quite a bit of work.. "
<< nm->poolSize() << endl;
Chat() << "....node manager contains " << nm->poolSize()
<< " nodes before cleanup" << endl;
d_iteUtilities.clear();
Rewriter::clearCaches();
nm->reclaimZombiesUntil(options::zombieHuntThreshold());
Chat() << "....node manager contains " << nm->poolSize()
<< " nodes after cleanup" << endl;
}
}
}
// Do theory specific preprocessing passes
TheoryEngine* theory_engine = d_preprocContext->getTheoryEngine();
if (theory_engine->getLogicInfo().isTheoryEnabled(theory::THEORY_ARITH)
&& !options::incrementalSolving())
{
if (!simpDidALotOfWork)
{
util::ContainsTermITEVisitor& contains =
*(d_iteUtilities.getContainsVisitor());
arith::ArithIteUtils aiteu(contains,
d_preprocContext->getUserContext(),
theory_engine->getModel());
bool anyItes = false;
for (size_t i = 0, size = assertionsToPreprocess->size(); i < size; ++i)
{
Node curr = (*assertionsToPreprocess)[i];
if (contains.containsTermITE(curr))
{
anyItes = true;
Node res = aiteu.reduceVariablesInItes(curr);
Debug("arith::ite::red") << "@ " << i << " ... " << curr << endl
<< " ->" << res << endl;
if (curr != res)
{
Node more = aiteu.reduceConstantIteByGCD(res);
Debug("arith::ite::red") << " gcd->" << more << endl;
Node morer = Rewriter::rewrite(more);
assertionsToPreprocess->replace(i, morer);
}
}
}
if (!anyItes)
{
unsigned prevSubCount = aiteu.getSubCount();
aiteu.learnSubstitutions(assertionsToPreprocess->ref());
if (prevSubCount < aiteu.getSubCount())
{
d_statistics.d_arithSubstitutionsAdded +=
aiteu.getSubCount() - prevSubCount;
bool anySuccess = false;
for (size_t i = 0, N = assertionsToPreprocess->size(); i < N; ++i)
{
Node curr = (*assertionsToPreprocess)[i];
Node next = Rewriter::rewrite(aiteu.applySubstitutions(curr));
Node res = aiteu.reduceVariablesInItes(next);
Debug("arith::ite::red") << "@ " << i << " ... " << next << endl
<< " ->" << res << endl;
Node more = aiteu.reduceConstantIteByGCD(res);
Debug("arith::ite::red") << " gcd->" << more << endl;
if (more != next)
{
anySuccess = true;
break;
}
}
for (size_t i = 0, N = assertionsToPreprocess->size();
anySuccess && i < N;
++i)
{
Node curr = (*assertionsToPreprocess)[i];
Node next = Rewriter::rewrite(aiteu.applySubstitutions(curr));
Node res = aiteu.reduceVariablesInItes(next);
Debug("arith::ite::red") << "@ " << i << " ... " << next << endl
<< " ->" << res << endl;
Node more = aiteu.reduceConstantIteByGCD(res);
Debug("arith::ite::red") << " gcd->" << more << endl;
Node morer = Rewriter::rewrite(more);
assertionsToPreprocess->replace(i, morer);
}
}
}
}
}
return result;
}
/* -------------------------------------------------------------------------- */
ITESimp::ITESimp(PreprocessingPassContext* preprocContext)
: PreprocessingPass(preprocContext, "ite-simp")
{
}
PreprocessingPassResult ITESimp::applyInternal(
AssertionPipeline* assertionsToPreprocess)
{
d_preprocContext->spendResource(Resource::PreprocessStep);
size_t nasserts = assertionsToPreprocess->size();
for (size_t i = 0; i < nasserts; ++i)
{
d_preprocContext->spendResource(Resource::PreprocessStep);
Node simp = simpITE(&d_iteUtilities, (*assertionsToPreprocess)[i]);
assertionsToPreprocess->replace(i, simp);
if (simp.isConst() && !simp.getConst<bool>())
{
return PreprocessingPassResult::CONFLICT;
}
}
bool done = doneSimpITE(assertionsToPreprocess);
if (nasserts < assertionsToPreprocess->size())
{
compressBeforeRealAssertions(assertionsToPreprocess, nasserts);
}
return done ? PreprocessingPassResult::NO_CONFLICT
: PreprocessingPassResult::CONFLICT;
}
/* -------------------------------------------------------------------------- */
} // namespace passes
} // namespace preprocessing
} // namespace cvc5
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