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GCC Code Coverage Report

Directory:	.		Exec	Total	Coverage
File:	src/preprocessing/passes/non_clausal_simp.cpp	Lines:	216	224	96.4 %
Date:	2021-05-22	Branches:	488	1178	41.4 %


/******************************************************************************
 * Top contributors (to current version):
 *   Aina Niemetz, Andrew Reynolds, Gereon Kremer
 *
 * 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.
 * ****************************************************************************
 *
 * Non-clausal simplification preprocessing pass.
 *
 * Run the nonclausal solver and try to solve all assigned theory literals.
 */

#include "preprocessing/passes/non_clausal_simp.h"

#include <vector>

#include "context/cdo.h"
#include "options/smt_options.h"
#include "preprocessing/assertion_pipeline.h"
#include "preprocessing/preprocessing_pass_context.h"
#include "smt/preprocess_proof_generator.h"
#include "smt/smt_statistics_registry.h"
#include "theory/booleans/circuit_propagator.h"
#include "theory/theory.h"
#include "theory/theory_engine.h"
#include "theory/theory_model.h"
#include "theory/trust_substitutions.h"

using namespace cvc5;
using namespace cvc5::theory;

namespace cvc5 {
namespace preprocessing {
namespace passes {

/* -------------------------------------------------------------------------- */

NonClausalSimp::Statistics::Statistics()
    : d_numConstantProps(smtStatisticsRegistry().registerInt(
        "preprocessing::passes::NonClausalSimp::NumConstantProps"))
{
}


/* -------------------------------------------------------------------------- */

NonClausalSimp::NonClausalSimp(PreprocessingPassContext* preprocContext)
    : PreprocessingPass(preprocContext, "non-clausal-simp"),
      d_pnm(preprocContext->getProofNodeManager()),
      d_llpg(d_pnm ? new smt::PreprocessProofGenerator(
                         d_pnm,
                         preprocContext->getUserContext(),
                         "NonClausalSimp::llpg")
                   : nullptr),
      d_llra(d_pnm ? new LazyCDProof(d_pnm,
                                     nullptr,
                                     preprocContext->getUserContext(),
                                     "NonClausalSimp::llra")
                   : nullptr),
      d_tsubsList(preprocContext->getUserContext())
{
}

PreprocessingPassResult NonClausalSimp::applyInternal(
    AssertionPipeline* assertionsToPreprocess)
{
  d_preprocContext->spendResource(Resource::PreprocessStep);

  theory::booleans::CircuitPropagator* propagator =
      d_preprocContext->getCircuitPropagator();

  for (size_t i = 0, size = assertionsToPreprocess->size(); i < size; ++i)
  {
    Trace("non-clausal-simplify") << "Assertion #" << i << " : "
                                  << (*assertionsToPreprocess)[i] << std::endl;
  }

  if (propagator->getNeedsFinish())
  {
    propagator->finish();
    propagator->setNeedsFinish(false);
  }
  propagator->initialize();

  // Assert all the assertions to the propagator
  Trace("non-clausal-simplify") << "asserting to propagator" << std::endl;
  for (size_t i = 0, size = assertionsToPreprocess->size(); i < size; ++i)
  {
    Assert(Rewriter::rewrite((*assertionsToPreprocess)[i])
           == (*assertionsToPreprocess)[i]);
    // Don't reprocess substitutions
    if (assertionsToPreprocess->isSubstsIndex(i))
    {
      continue;
    }
    Trace("non-clausal-simplify")
        << "asserting " << (*assertionsToPreprocess)[i] << std::endl;
    Debug("cores") << "propagator->assertTrue: " << (*assertionsToPreprocess)[i]
                   << std::endl;
    propagator->assertTrue((*assertionsToPreprocess)[i]);
  }

  Trace("non-clausal-simplify") << "propagating" << std::endl;
  TrustNode conf = propagator->propagate();
  if (!conf.isNull())
  {
    // If in conflict, just return false
    Trace("non-clausal-simplify")
        << "conflict in non-clausal propagation" << std::endl;
    assertionsToPreprocess->clear();
    assertionsToPreprocess->pushBackTrusted(conf);
    propagator->setNeedsFinish(true);
    return PreprocessingPassResult::CONFLICT;
  }

  Trace("non-clausal-simplify")
      << "Iterate through " << propagator->getLearnedLiterals().size()
      << " learned literals." << std::endl;
  // No conflict, go through the literals and solve them
  context::Context* u = d_preprocContext->getUserContext();
  TrustSubstitutionMap& ttls = d_preprocContext->getTopLevelSubstitutions();
  CVC5_UNUSED SubstitutionMap& top_level_substs = ttls.get();
  // constant propagations
  std::shared_ptr<TrustSubstitutionMap> constantPropagations =
      std::make_shared<TrustSubstitutionMap>(
          u, d_pnm, "NonClausalSimp::cprop", PfRule::PREPROCESS_LEMMA);
  SubstitutionMap& cps = constantPropagations->get();
  // new substitutions
  std::shared_ptr<TrustSubstitutionMap> newSubstitutions =
      std::make_shared<TrustSubstitutionMap>(
          u, d_pnm, "NonClausalSimp::newSubs", PfRule::PREPROCESS_LEMMA);
  SubstitutionMap& nss = newSubstitutions->get();

  size_t j = 0;
  std::vector<TrustNode>& learned_literals = propagator->getLearnedLiterals();
  // if proofs are enabled, we will need to track the proofs of learned literals
  if (isProofEnabled())
  {
    d_tsubsList.push_back(constantPropagations);
    d_tsubsList.push_back(newSubstitutions);
    for (const TrustNode& tll : learned_literals)
    {
      d_llpg->notifyNewTrustedAssert(tll);
    }
  }
  for (size_t i = 0, size = learned_literals.size(); i < size; ++i)
  {
    // Simplify the literal we learned wrt previous substitutions
    Node learnedLiteral = learned_literals[i].getNode();
    Assert(Rewriter::rewrite(learnedLiteral) == learnedLiteral);
    Assert(top_level_substs.apply(learnedLiteral) == learnedLiteral);
    // process the learned literal with substitutions and const propagations
    learnedLiteral = processLearnedLit(
        learnedLiteral, newSubstitutions.get(), constantPropagations.get());
    Trace("non-clausal-simplify")
        << "Process learnedLiteral, after constProp : " << learnedLiteral
        << std::endl;
    // It might just simplify to a constant
    if (learnedLiteral.isConst())
    {
      if (learnedLiteral.getConst<bool>())
      {
        // If the learned literal simplifies to true, it's redundant
        continue;
      }
      else
      {
        // If the learned literal simplifies to false, we're in conflict
        Trace("non-clausal-simplify")
            << "conflict with " << learned_literals[i].getNode() << std::endl;
        assertionsToPreprocess->clear();
        Node n = NodeManager::currentNM()->mkConst<bool>(false);
        assertionsToPreprocess->push_back(n, false, false, d_llpg.get());
        propagator->setNeedsFinish(true);
        return PreprocessingPassResult::CONFLICT;
      }
    }

    // Solve it with the corresponding theory, possibly adding new
    // substitutions to newSubstitutions
    Trace("non-clausal-simplify") << "solving " << learnedLiteral << std::endl;

    TrustNode tlearnedLiteral =
        TrustNode::mkTrustLemma(learnedLiteral, d_llpg.get());
    Theory::PPAssertStatus solveStatus =
        d_preprocContext->getTheoryEngine()->solve(tlearnedLiteral,
                                                   *newSubstitutions.get());

    switch (solveStatus)
    {
      case Theory::PP_ASSERT_STATUS_SOLVED:
      {
        // The literal should rewrite to true
        Trace("non-clausal-simplify")
            << "solved " << learnedLiteral << std::endl;
        Assert(Rewriter::rewrite(nss.apply(learnedLiteral)).isConst());
        // else fall through
        break;
      }
      case Theory::PP_ASSERT_STATUS_CONFLICT:
      {
        // If in conflict, we return false
        Trace("non-clausal-simplify")
            << "conflict while solving " << learnedLiteral << std::endl;
        assertionsToPreprocess->clear();
        Node n = NodeManager::currentNM()->mkConst<bool>(false);
        assertionsToPreprocess->push_back(n);
        propagator->setNeedsFinish(true);
        return PreprocessingPassResult::CONFLICT;
      }
      default:
        if (learnedLiteral.getKind() == kind::EQUAL
            && (learnedLiteral[0].isConst() || learnedLiteral[1].isConst()))
        {
          // constant propagation
          TNode t;
          TNode c;
          if (learnedLiteral[0].isConst())
          {
            t = learnedLiteral[1];
            c = learnedLiteral[0];
          }
          else
          {
            t = learnedLiteral[0];
            c = learnedLiteral[1];
          }
          Assert(!t.isConst());
          Assert(cps.apply(t, true) == t);
          Assert(top_level_substs.apply(t) == t);
          Assert(nss.apply(t) == t);
          // also add to learned literal
          ProofGenerator* cpg = constantPropagations->addSubstitutionSolved(
              t, c, tlearnedLiteral);
          // We need to justify (= t c) as a literal, since it is reasserted
          // to the assertion pipeline below. We do this with the proof
          // generator returned by the above call.
          if (isProofEnabled())
          {
            d_llpg->notifyNewAssert(t.eqNode(c), cpg);
          }
        }
        else
        {
          // Keep the literal
          learned_literals[j++] = learned_literals[i];
        }
        break;
    }
  }

#ifdef CVC5_ASSERTIONS
  // NOTE: When debugging this code, consider moving this check inside of the
  // loop over propagator->getLearnedLiterals(). This check has been moved
  // outside because it is costly for certain inputs (see bug 508).
  //
  // Check data structure invariants:
  // 1. for each lhs of top_level_substs, does not appear anywhere in rhs of
  // top_level_substs or anywhere in constantPropagations
  // 2. each lhs of constantPropagations rewrites to itself
  // 3. if l -> r is a constant propagation and l is a subterm of l' with l' ->
  // r' another constant propagation, then l'[l/r] -> r' should be a
  //    constant propagation too
  // 4. each lhs of constantPropagations is different from each rhs
  for (SubstitutionMap::iterator pos = nss.begin(); pos != nss.end(); ++pos)
  {
    Assert((*pos).first.isVar());
    Assert(top_level_substs.apply((*pos).first) == (*pos).first);
    Assert(top_level_substs.apply((*pos).second) == (*pos).second);
    Node app = nss.apply((*pos).second);
    Assert(nss.apply(app) == app);
  }
  for (SubstitutionMap::iterator pos = cps.begin(); pos != cps.end(); ++pos)
  {
    Assert((*pos).second.isConst());
    Assert(Rewriter::rewrite((*pos).first) == (*pos).first);
    Assert(cps.apply((*pos).second) == (*pos).second);
  }
#endif /* CVC5_ASSERTIONS */

  // Resize the learnt
  Trace("non-clausal-simplify")
      << "Resize non-clausal learned literals to " << j << std::endl;
  learned_literals.resize(j);

  std::unordered_set<TNode> s;
  for (size_t i = 0, size = assertionsToPreprocess->size(); i < size; ++i)
  {
    Node assertion = (*assertionsToPreprocess)[i];
    TrustNode assertionNew = newSubstitutions->applyTrusted(assertion);
    Trace("non-clausal-simplify") << "assertion = " << assertion << std::endl;
    if (!assertionNew.isNull())
    {
      Trace("non-clausal-simplify")
          << "assertionNew = " << assertionNew.getNode() << std::endl;
      assertionsToPreprocess->replaceTrusted(i, assertionNew);
      assertion = assertionNew.getNode();
      Assert(Rewriter::rewrite(assertion) == assertion);
    }
    for (;;)
    {
      assertionNew = constantPropagations->applyTrusted(assertion);
      if (assertionNew.isNull())
      {
        break;
      }
      Assert(assertionNew.getNode() != assertion);
      assertionsToPreprocess->replaceTrusted(i, assertionNew);
      assertion = assertionNew.getNode();
      d_statistics.d_numConstantProps += 1;
      Trace("non-clausal-simplify")
          << "assertionNew = " << assertion << std::endl;
    }
    s.insert(assertion);
    Trace("non-clausal-simplify")
        << "non-clausal preprocessed: " << assertion << std::endl;
  }

  // If necessary, add as assertions if needed (when incremental). This is
  // necessary because certain variables cannot truly be eliminated when
  // we are in incremental mode. For example, say our first call to check-sat
  // is a formula F containing variable x. On the second call to check-sat,
  // say we solve a top-level assertion (= x t). Since the solver already has
  // constraints involving x, we must still keep (= x t) as an assertion.
  // However, notice that we do not retract the substitution { x -> t }. This
  // means that all *subsequent* assertions after (= x t) will replace x by t.
  if (assertionsToPreprocess->storeSubstsInAsserts())
  {
    for (const std::pair<const Node, const Node>& pos: nss)
    {
      Node lhs = pos.first;
      // If using incremental, we must check whether this variable has occurred
      // before now. If it has, we must add as an assertion.
      if (d_preprocContext->getSymsInAssertions().contains(lhs))
      {
        // if it has, the substitution becomes an assertion
        TrustNode trhs = newSubstitutions->applyTrusted(lhs);
        Assert(!trhs.isNull());
        Trace("non-clausal-simplify")
            << "substitute: will notify SAT layer of substitution: "
            << trhs.getProven() << std::endl;
        assertionsToPreprocess->addSubstitutionNode(trhs.getProven(),
                                                    trhs.getGenerator());
      }
    }
  }

  Assert(assertionsToPreprocess->getRealAssertionsEnd()
         <= assertionsToPreprocess->size());
  // Learned literals to conjoin. If proofs are enabled, all these are
  // justified by d_llpg.
  std::vector<Node> learnedLitsToConjoin;

  for (size_t i = 0; i < learned_literals.size(); ++i)
  {
    Node learned = learned_literals[i].getNode();
    Assert(top_level_substs.apply(learned) == learned);
    // process learned literal
    learned = processLearnedLit(
        learned, newSubstitutions.get(), constantPropagations.get());
    if (s.find(learned) != s.end())
    {
      continue;
    }
    s.insert(learned);
    learnedLitsToConjoin.push_back(learned);
    Trace("non-clausal-simplify")
        << "non-clausal learned : " << learned << std::endl;
  }
  learned_literals.clear();

  for (SubstitutionMap::iterator pos = cps.begin(); pos != cps.end(); ++pos)
  {
    Node cProp = (*pos).first.eqNode((*pos).second);
    Assert(top_level_substs.apply(cProp) == cProp);
    // process learned literal (substitutions only)
    cProp = processLearnedLit(cProp, newSubstitutions.get(), nullptr);
    if (s.find(cProp) != s.end())
    {
      continue;
    }
    s.insert(cProp);
    learnedLitsToConjoin.push_back(cProp);
    Trace("non-clausal-simplify")
        << "non-clausal constant propagation : " << cProp << std::endl;
  }

  // Add new substitutions to topLevelSubstitutions
  // Note that we don't have to keep rhs's in full solved form
  // because SubstitutionMap::apply does a fixed-point iteration when
  // substituting
  ttls.addSubstitutions(*newSubstitutions.get());

  if (!learnedLitsToConjoin.empty())
  {
    size_t replIndex = assertionsToPreprocess->getRealAssertionsEnd() - 1;
    Node newConj = NodeManager::currentNM()->mkAnd(learnedLitsToConjoin);
    Trace("non-clausal-simplify")
        << "non-clausal simplification, reassert: " << newConj << std::endl;
    ProofGenerator* pg = nullptr;
    if (isProofEnabled())
    {
      // justify in d_llra
      for (const Node& lit : learnedLitsToConjoin)
      {
        d_llra->addLazyStep(lit, d_llpg.get());
      }
      if (learnedLitsToConjoin.size() > 1)
      {
        d_llra->addStep(newConj, PfRule::AND_INTRO, learnedLitsToConjoin, {});
        pg = d_llra.get();
      }
      else
      {
        // otherwise we ask the learned literal proof generator directly
        pg = d_llpg.get();
      }
    }
    // ------- from d_llpg    --------- from d_llpg
    //  conj[0]       ....    d_conj[n]
    // -------------------------------- AND_INTRO
    //  newConj
    // where newConj is conjoined at the given index
    assertionsToPreprocess->conjoin(replIndex, newConj, pg);
  }

  propagator->setNeedsFinish(true);

  // Note that typically ttls.apply(assert)==assert here.
  // However, this invariant is invalidated for cases where we use explicit
  // equality assertions for variables solved in incremental mode that already
  // exist in assertions, as described above.

  return PreprocessingPassResult::NO_CONFLICT;
}

bool NonClausalSimp::isProofEnabled() const { return d_pnm != nullptr; }

Node NonClausalSimp::processLearnedLit(Node lit,
                                       theory::TrustSubstitutionMap* subs,
                                       theory::TrustSubstitutionMap* cp)
{
  TrustNode tlit;
  if (subs != nullptr)
  {
    tlit = subs->applyTrusted(lit);
    if (!tlit.isNull())
    {
      lit = processRewrittenLearnedLit(tlit);
    }
    Trace("non-clausal-simplify")
        << "Process learnedLiteral, after newSubs : " << lit << std::endl;
  }
  // apply to fixed point
  if (cp != nullptr)
  {
    for (;;)
    {
      tlit = cp->applyTrusted(lit);
      if (tlit.isNull())
      {
        break;
      }
      Assert(lit != tlit.getNode());
      lit = processRewrittenLearnedLit(tlit);
      d_statistics.d_numConstantProps += 1;
    }
  }
  return lit;
}

Node NonClausalSimp::processRewrittenLearnedLit(theory::TrustNode trn)
{
  if (isProofEnabled())
  {
    d_llpg->notifyTrustedPreprocessed(trn);
  }
  // return the node
  return trn.getNode();
}

}  // namespace passes
}  // namespace preprocessing
}  // namespace cvc5


Generated by: GCOVR (Version 3.2)

Line	Exec	Source
1		/******************************************************************************
2		* Top contributors (to current version):
3		* Aina Niemetz, Andrew Reynolds, Gereon Kremer
4		*
5		* This file is part of the cvc5 project.
6		*
7		* Copyright (c) 2009-2021 by the authors listed in the file AUTHORS
8		* in the top-level source directory and their institutional affiliations.
9		* All rights reserved. See the file COPYING in the top-level source
10		* directory for licensing information.
11		* ****************************************************************************
12		*
13		* Non-clausal simplification preprocessing pass.
14		*
15		* Run the nonclausal solver and try to solve all assigned theory literals.
16		*/
17
18		#include "preprocessing/passes/non_clausal_simp.h"
19
20		#include <vector>
21
22		#include "context/cdo.h"
23		#include "options/smt_options.h"
24		#include "preprocessing/assertion_pipeline.h"
25		#include "preprocessing/preprocessing_pass_context.h"
26		#include "smt/preprocess_proof_generator.h"
27		#include "smt/smt_statistics_registry.h"
28		#include "theory/booleans/circuit_propagator.h"
29		#include "theory/theory.h"
30		#include "theory/theory_engine.h"
31		#include "theory/theory_model.h"
32		#include "theory/trust_substitutions.h"
33
34		using namespace cvc5;
35		using namespace cvc5::theory;
36
37		namespace cvc5 {
38		namespace preprocessing {
39		namespace passes {
40
41		/* -------------------------------------------------------------------------- */
42
43	9459	NonClausalSimp::Statistics::Statistics()
44	9459	: d_numConstantProps(smtStatisticsRegistry().registerInt(
45	9459	"preprocessing::passes::NonClausalSimp::NumConstantProps"))
46		{
47	9459	}
48
49
50		/* -------------------------------------------------------------------------- */
51
52	9459	NonClausalSimp::NonClausalSimp(PreprocessingPassContext* preprocContext)
53		: PreprocessingPass(preprocContext, "non-clausal-simp"),
54	9459	d_pnm(preprocContext->getProofNodeManager()),
55	9459	d_llpg(d_pnm ? new smt::PreprocessProofGenerator(
56		d_pnm,
57	3600	preprocContext->getUserContext(),
58	3600	"NonClausalSimp::llpg")
59		: nullptr),
60	9459	d_llra(d_pnm ? new LazyCDProof(d_pnm,
61		nullptr,
62	3600	preprocContext->getUserContext(),
63	3600	"NonClausalSimp::llra")
64		: nullptr),
65	52236	d_tsubsList(preprocContext->getUserContext())
66		{
67	9459	}
68
69	10277	PreprocessingPassResult NonClausalSimp::applyInternal(
70		AssertionPipeline* assertionsToPreprocess)
71		{
72	10277	d_preprocContext->spendResource(Resource::PreprocessStep);
73
74		theory::booleans::CircuitPropagator* propagator =
75	10277	d_preprocContext->getCircuitPropagator();
76
77	93255	for (size_t i = 0, size = assertionsToPreprocess->size(); i < size; ++i)
78		{
79	165956	Trace("non-clausal-simplify") << "Assertion #" << i << " : "
80	82978	<< (*assertionsToPreprocess)[i] << std::endl;
81		}
82
83	10277	if (propagator->getNeedsFinish())
84		{
85	3705	propagator->finish();
86	3705	propagator->setNeedsFinish(false);
87		}
88	10277	propagator->initialize();
89
90		// Assert all the assertions to the propagator
91	10277	Trace("non-clausal-simplify") << "asserting to propagator" << std::endl;
92	93255	for (size_t i = 0, size = assertionsToPreprocess->size(); i < size; ++i)
93		{
94	82978	Assert(Rewriter::rewrite((*assertionsToPreprocess)[i])
95		== (*assertionsToPreprocess)[i]);
96		// Don't reprocess substitutions
97	82978	if (assertionsToPreprocess->isSubstsIndex(i))
98		{
99	2591	continue;
100		}
101	160774	Trace("non-clausal-simplify")
102	80387	<< "asserting " << (*assertionsToPreprocess)[i] << std::endl;
103	160774	Debug("cores") << "propagator->assertTrue: " << (*assertionsToPreprocess)[i]
104	80387	<< std::endl;
105	80387	propagator->assertTrue((*assertionsToPreprocess)[i]);
106		}
107
108	10277	Trace("non-clausal-simplify") << "propagating" << std::endl;
109	20554	TrustNode conf = propagator->propagate();
110	10277	if (!conf.isNull())
111		{
112		// If in conflict, just return false
113	1802	Trace("non-clausal-simplify")
114	901	<< "conflict in non-clausal propagation" << std::endl;
115	901	assertionsToPreprocess->clear();
116	901	assertionsToPreprocess->pushBackTrusted(conf);
117	901	propagator->setNeedsFinish(true);
118	901	return PreprocessingPassResult::CONFLICT;
119		}
120
121	18752	Trace("non-clausal-simplify")
122	18752	<< "Iterate through " << propagator->getLearnedLiterals().size()
123	9376	<< " learned literals." << std::endl;
124		// No conflict, go through the literals and solve them
125	9376	context::Context* u = d_preprocContext->getUserContext();
126	9376	TrustSubstitutionMap& ttls = d_preprocContext->getTopLevelSubstitutions();
127	9376	CVC5_UNUSED SubstitutionMap& top_level_substs = ttls.get();
128		// constant propagations
129		std::shared_ptr<TrustSubstitutionMap> constantPropagations =
130		std::make_shared<TrustSubstitutionMap>(
131	18752	u, d_pnm, "NonClausalSimp::cprop", PfRule::PREPROCESS_LEMMA);
132	9376	SubstitutionMap& cps = constantPropagations->get();
133		// new substitutions
134		std::shared_ptr<TrustSubstitutionMap> newSubstitutions =
135		std::make_shared<TrustSubstitutionMap>(
136	18752	u, d_pnm, "NonClausalSimp::newSubs", PfRule::PREPROCESS_LEMMA);
137	9376	SubstitutionMap& nss = newSubstitutions->get();
138
139	9376	size_t j = 0;
140	9376	std::vector<TrustNode>& learned_literals = propagator->getLearnedLiterals();
141		// if proofs are enabled, we will need to track the proofs of learned literals
142	9376	if (isProofEnabled())
143		{
144	1755	d_tsubsList.push_back(constantPropagations);
145	1755	d_tsubsList.push_back(newSubstitutions);
146	30438	for (const TrustNode& tll : learned_literals)
147		{
148	28683	d_llpg->notifyNewTrustedAssert(tll);
149		}
150		}
151	122944	for (size_t i = 0, size = learned_literals.size(); i < size; ++i)
152		{
153		// Simplify the literal we learned wrt previous substitutions
154	226618	Node learnedLiteral = learned_literals[i].getNode();
155	113721	Assert(Rewriter::rewrite(learnedLiteral) == learnedLiteral);
156	113721	Assert(top_level_substs.apply(learnedLiteral) == learnedLiteral);
157		// process the learned literal with substitutions and const propagations
158	113721	learnedLiteral = processLearnedLit(
159		learnedLiteral, newSubstitutions.get(), constantPropagations.get());
160	227442	Trace("non-clausal-simplify")
161	113721	<< "Process learnedLiteral, after constProp : " << learnedLiteral
162	113721	<< std::endl;
163		// It might just simplify to a constant
164	113721	if (learnedLiteral.isConst())
165		{
166	824	if (learnedLiteral.getConst<bool>())
167		{
168		// If the learned literal simplifies to true, it's redundant
169	671	continue;
170		}
171		else
172		{
173		// If the learned literal simplifies to false, we're in conflict
174	306	Trace("non-clausal-simplify")
175	153	<< "conflict with " << learned_literals[i].getNode() << std::endl;
176	153	assertionsToPreprocess->clear();
177	306	Node n = NodeManager::currentNM()->mkConst<bool>(false);
178	153	assertionsToPreprocess->push_back(n, false, false, d_llpg.get());
179	153	propagator->setNeedsFinish(true);
180	153	return PreprocessingPassResult::CONFLICT;
181		}
182		}
183
184		// Solve it with the corresponding theory, possibly adding new
185		// substitutions to newSubstitutions
186	112897	Trace("non-clausal-simplify") << "solving " << learnedLiteral << std::endl;
187
188		TrustNode tlearnedLiteral =
189	225794	TrustNode::mkTrustLemma(learnedLiteral, d_llpg.get());
190		Theory::PPAssertStatus solveStatus =
191	338691	d_preprocContext->getTheoryEngine()->solve(tlearnedLiteral,
192	225794	*newSubstitutions.get());
193
194	112897	switch (solveStatus)
195		{
196	48236	case Theory::PP_ASSERT_STATUS_SOLVED:
197		{
198		// The literal should rewrite to true
199	96472	Trace("non-clausal-simplify")
200	48236	<< "solved " << learnedLiteral << std::endl;
201	48236	Assert(Rewriter::rewrite(nss.apply(learnedLiteral)).isConst());
202		// else fall through
203	48236	break;
204		}
205		case Theory::PP_ASSERT_STATUS_CONFLICT:
206		{
207		// If in conflict, we return false
208		Trace("non-clausal-simplify")
209		<< "conflict while solving " << learnedLiteral << std::endl;
210		assertionsToPreprocess->clear();
211		Node n = NodeManager::currentNM()->mkConst<bool>(false);
212		assertionsToPreprocess->push_back(n);
213		propagator->setNeedsFinish(true);
214		return PreprocessingPassResult::CONFLICT;
215		}
216	64661	default:
217	129322	if (learnedLiteral.getKind() == kind::EQUAL
218	129322	&& (learnedLiteral[0].isConst() \|\| learnedLiteral[1].isConst()))
219		{
220		// constant propagation
221	11052	TNode t;
222	11052	TNode c;
223	5526	if (learnedLiteral[0].isConst())
224		{
225	198	t = learnedLiteral[1];
226	198	c = learnedLiteral[0];
227		}
228		else
229		{
230	5328	t = learnedLiteral[0];
231	5328	c = learnedLiteral[1];
232		}
233	5526	Assert(!t.isConst());
234	5526	Assert(cps.apply(t, true) == t);
235	5526	Assert(top_level_substs.apply(t) == t);
236	5526	Assert(nss.apply(t) == t);
237		// also add to learned literal
238	11052	ProofGenerator* cpg = constantPropagations->addSubstitutionSolved(
239	5526	t, c, tlearnedLiteral);
240		// We need to justify (= t c) as a literal, since it is reasserted
241		// to the assertion pipeline below. We do this with the proof
242		// generator returned by the above call.
243	5526	if (isProofEnabled())
244		{
245	1440	d_llpg->notifyNewAssert(t.eqNode(c), cpg);
246		}
247		}
248		else
249		{
250		// Keep the literal
251	59135	learned_literals[j++] = learned_literals[i];
252		}
253	64661	break;
254		}
255		}
256
257		#ifdef CVC5_ASSERTIONS
258		// NOTE: When debugging this code, consider moving this check inside of the
259		// loop over propagator->getLearnedLiterals(). This check has been moved
260		// outside because it is costly for certain inputs (see bug 508).
261		//
262		// Check data structure invariants:
263		// 1. for each lhs of top_level_substs, does not appear anywhere in rhs of
264		// top_level_substs or anywhere in constantPropagations
265		// 2. each lhs of constantPropagations rewrites to itself
266		// 3. if l -> r is a constant propagation and l is a subterm of l' with l' ->
267		// r' another constant propagation, then l'[l/r] -> r' should be a
268		// constant propagation too
269		// 4. each lhs of constantPropagations is different from each rhs
270	56864	for (SubstitutionMap::iterator pos = nss.begin(); pos != nss.end(); ++pos)
271		{
272	47641	Assert((*pos).first.isVar());
273	47641	Assert(top_level_substs.apply((pos).first) == (pos).first);
274	47641	Assert(top_level_substs.apply((pos).second) == (pos).second);
275	95282	Node app = nss.apply((*pos).second);
276	47641	Assert(nss.apply(app) == app);
277		}
278	14731	for (SubstitutionMap::iterator pos = cps.begin(); pos != cps.end(); ++pos)
279		{
280	5508	Assert((*pos).second.isConst());
281	5508	Assert(Rewriter::rewrite((pos).first) == (pos).first);
282	5508	Assert(cps.apply((pos).second) == (pos).second);
283		}
284		#endif /* CVC5_ASSERTIONS */
285
286		// Resize the learnt
287	18446	Trace("non-clausal-simplify")
288	9223	<< "Resize non-clausal learned literals to " << j << std::endl;
289	9223	learned_literals.resize(j);
290
291	18446	std::unordered_set<TNode> s;
292	87442	for (size_t i = 0, size = assertionsToPreprocess->size(); i < size; ++i)
293		{
294	156438	Node assertion = (*assertionsToPreprocess)[i];
295	156438	TrustNode assertionNew = newSubstitutions->applyTrusted(assertion);
296	78219	Trace("non-clausal-simplify") << "assertion = " << assertion << std::endl;
297	78219	if (!assertionNew.isNull())
298		{
299	57534	Trace("non-clausal-simplify")
300	28767	<< "assertionNew = " << assertionNew.getNode() << std::endl;
301	28767	assertionsToPreprocess->replaceTrusted(i, assertionNew);
302	28767	assertion = assertionNew.getNode();
303	28767	Assert(Rewriter::rewrite(assertion) == assertion);
304		}
305		for (;;)
306		{
307	80301	assertionNew = constantPropagations->applyTrusted(assertion);
308	79260	if (assertionNew.isNull())
309		{
310	78219	break;
311		}
312	1041	Assert(assertionNew.getNode() != assertion);
313	1041	assertionsToPreprocess->replaceTrusted(i, assertionNew);
314	1041	assertion = assertionNew.getNode();
315	1041	d_statistics.d_numConstantProps += 1;
316	2082	Trace("non-clausal-simplify")
317	1041	<< "assertionNew = " << assertion << std::endl;
318		}
319	78219	s.insert(assertion);
320	156438	Trace("non-clausal-simplify")
321	78219	<< "non-clausal preprocessed: " << assertion << std::endl;
322		}
323
324		// If necessary, add as assertions if needed (when incremental). This is
325		// necessary because certain variables cannot truly be eliminated when
326		// we are in incremental mode. For example, say our first call to check-sat
327		// is a formula F containing variable x. On the second call to check-sat,
328		// say we solve a top-level assertion (= x t). Since the solver already has
329		// constraints involving x, we must still keep (= x t) as an assertion.
330		// However, notice that we do not retract the substitution { x -> t }. This
331		// means that all subsequent assertions after (= x t) will replace x by t.
332	9223	if (assertionsToPreprocess->storeSubstsInAsserts())
333		{
334	5112	for (const std::pair<const Node, const Node>& pos: nss)
335		{
336	5448	Node lhs = pos.first;
337		// If using incremental, we must check whether this variable has occurred
338		// before now. If it has, we must add as an assertion.
339	2724	if (d_preprocContext->getSymsInAssertions().contains(lhs))
340		{
341		// if it has, the substitution becomes an assertion
342	2682	TrustNode trhs = newSubstitutions->applyTrusted(lhs);
343	1341	Assert(!trhs.isNull());
344	2682	Trace("non-clausal-simplify")
345	1341	<< "substitute: will notify SAT layer of substitution: "
346	1341	<< trhs.getProven() << std::endl;
347	1341	assertionsToPreprocess->addSubstitutionNode(trhs.getProven(),
348		trhs.getGenerator());
349		}
350		}
351		}
352
353	9223	Assert(assertionsToPreprocess->getRealAssertionsEnd()
354		<= assertionsToPreprocess->size());
355		// Learned literals to conjoin. If proofs are enabled, all these are
356		// justified by d_llpg.
357	18446	std::vector<Node> learnedLitsToConjoin;
358
359	67802	for (size_t i = 0; i < learned_literals.size(); ++i)
360		{
361	96142	Node learned = learned_literals[i].getNode();
362	58579	Assert(top_level_substs.apply(learned) == learned);
363		// process learned literal
364	58579	learned = processLearnedLit(
365		learned, newSubstitutions.get(), constantPropagations.get());
366	58579	if (s.find(learned) != s.end())
367		{
368	21016	continue;
369		}
370	37563	s.insert(learned);
371	37563	learnedLitsToConjoin.push_back(learned);
372	75126	Trace("non-clausal-simplify")
373	37563	<< "non-clausal learned : " << learned << std::endl;
374		}
375	9223	learned_literals.clear();
376
377	14731	for (SubstitutionMap::iterator pos = cps.begin(); pos != cps.end(); ++pos)
378		{
379	10909	Node cProp = (pos).first.eqNode((pos).second);
380	5508	Assert(top_level_substs.apply(cProp) == cProp);
381		// process learned literal (substitutions only)
382	5508	cProp = processLearnedLit(cProp, newSubstitutions.get(), nullptr);
383	5508	if (s.find(cProp) != s.end())
384		{
385	107	continue;
386		}
387	5401	s.insert(cProp);
388	5401	learnedLitsToConjoin.push_back(cProp);
389	10802	Trace("non-clausal-simplify")
390	5401	<< "non-clausal constant propagation : " << cProp << std::endl;
391		}
392
393		// Add new substitutions to topLevelSubstitutions
394		// Note that we don't have to keep rhs's in full solved form
395		// because SubstitutionMap::apply does a fixed-point iteration when
396		// substituting
397	9223	ttls.addSubstitutions(*newSubstitutions.get());
398
399	9223	if (!learnedLitsToConjoin.empty())
400		{
401	2165	size_t replIndex = assertionsToPreprocess->getRealAssertionsEnd() - 1;
402	4330	Node newConj = NodeManager::currentNM()->mkAnd(learnedLitsToConjoin);
403	4330	Trace("non-clausal-simplify")
404	2165	<< "non-clausal simplification, reassert: " << newConj << std::endl;
405	2165	ProofGenerator* pg = nullptr;
406	2165	if (isProofEnabled())
407		{
408		// justify in d_llra
409	15352	for (const Node& lit : learnedLitsToConjoin)
410		{
411	14928	d_llra->addLazyStep(lit, d_llpg.get());
412		}
413	424	if (learnedLitsToConjoin.size() > 1)
414		{
415	319	d_llra->addStep(newConj, PfRule::AND_INTRO, learnedLitsToConjoin, {});
416	319	pg = d_llra.get();
417		}
418		else
419		{
420		// otherwise we ask the learned literal proof generator directly
421	105	pg = d_llpg.get();
422		}
423		}
424		// ------- from d_llpg --------- from d_llpg
425		// conj[0] .... d_conj[n]
426		// -------------------------------- AND_INTRO
427		// newConj
428		// where newConj is conjoined at the given index
429	2165	assertionsToPreprocess->conjoin(replIndex, newConj, pg);
430		}
431
432	9223	propagator->setNeedsFinish(true);
433
434		// Note that typically ttls.apply(assert)==assert here.
435		// However, this invariant is invalidated for cases where we use explicit
436		// equality assertions for variables solved in incremental mode that already
437		// exist in assertions, as described above.
438
439	9223	return PreprocessingPassResult::NO_CONFLICT;
440		}
441
442	58158	bool NonClausalSimp::isProofEnabled() const { return d_pnm != nullptr; }
443
444	177808	Node NonClausalSimp::processLearnedLit(Node lit,
445		theory::TrustSubstitutionMap* subs,
446		theory::TrustSubstitutionMap* cp)
447		{
448	355616	TrustNode tlit;
449	177808	if (subs != nullptr)
450		{
451	177808	tlit = subs->applyTrusted(lit);
452	177808	if (!tlit.isNull())
453		{
454	40951	lit = processRewrittenLearnedLit(tlit);
455		}
456	355616	Trace("non-clausal-simplify")
457	177808	<< "Process learnedLiteral, after newSubs : " << lit << std::endl;
458		}
459		// apply to fixed point
460	177808	if (cp != nullptr)
461		{
462		for (;;)
463		{
464	172580	tlit = cp->applyTrusted(lit);
465	172440	if (tlit.isNull())
466		{
467	172300	break;
468		}
469	140	Assert(lit != tlit.getNode());
470	140	lit = processRewrittenLearnedLit(tlit);
471	140	d_statistics.d_numConstantProps += 1;
472		}
473		}
474	355616	return lit;
475		}
476
477	41091	Node NonClausalSimp::processRewrittenLearnedLit(theory::TrustNode trn)
478		{
479	41091	if (isProofEnabled())
480		{
481	15386	d_llpg->notifyTrustedPreprocessed(trn);
482		}
483		// return the node
484	41091	return trn.getNode();
485		}
486
487		} // namespace passes
488		} // namespace preprocessing
489	28191	} // namespace cvc5