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/****************************************************************************** |
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* Top contributors (to current version): |
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* Aina Niemetz, Tim King, Andrew Reynolds |
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* |
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* This file is part of the cvc5 project. |
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* |
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* Copyright (c) 2009-2021 by the authors listed in the file AUTHORS |
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* in the top-level source directory and their institutional affiliations. |
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* All rights reserved. See the file COPYING in the top-level source |
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* directory for licensing information. |
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* **************************************************************************** |
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* |
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* ITE simplification preprocessing pass. |
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*/ |
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#include "preprocessing/passes/ite_simp.h" |
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#include <vector> |
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#include "options/base_options.h" |
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#include "options/smt_options.h" |
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#include "preprocessing/assertion_pipeline.h" |
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#include "preprocessing/preprocessing_pass_context.h" |
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#include "smt/smt_statistics_registry.h" |
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#include "smt_util/nary_builder.h" |
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#include "theory/arith/arith_ite_utils.h" |
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#include "theory/rewriter.h" |
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#include "theory/theory_engine.h" |
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using namespace std; |
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using namespace cvc5; |
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using namespace cvc5::theory; |
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namespace cvc5 { |
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namespace preprocessing { |
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namespace passes { |
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/* -------------------------------------------------------------------------- */ |
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namespace { |
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Node simpITE(util::ITEUtilities* ite_utils, TNode assertion) |
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{ |
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if (!ite_utils->containsTermITE(assertion)) |
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{ |
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return assertion; |
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} |
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else |
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{ |
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Node result = ite_utils->simpITE(assertion); |
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Node res_rewritten = Rewriter::rewrite(result); |
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if (options::simplifyWithCareEnabled()) |
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{ |
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Chat() << "starting simplifyWithCare()" << endl; |
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Node postSimpWithCare = ite_utils->simplifyWithCare(res_rewritten); |
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Chat() << "ending simplifyWithCare()" |
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<< " post simplifyWithCare()" << postSimpWithCare.getId() << endl; |
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result = Rewriter::rewrite(postSimpWithCare); |
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} |
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else |
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{ |
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result = res_rewritten; |
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} |
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return result; |
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} |
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} |
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/** |
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* Ensures the assertions asserted after index 'before' now effectively come |
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* before 'real_assertions_end'. |
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*/ |
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void compressBeforeRealAssertions(AssertionPipeline* assertionsToPreprocess, |
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size_t before) |
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{ |
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size_t cur_size = assertionsToPreprocess->size(); |
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if (before >= cur_size || assertionsToPreprocess->getRealAssertionsEnd() <= 0 |
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|| assertionsToPreprocess->getRealAssertionsEnd() >= cur_size) |
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{ |
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return; |
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} |
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// assertions |
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// original: [0 ... assertionsToPreprocess.getRealAssertionsEnd()) |
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// can be modified |
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// ites skolems [assertionsToPreprocess.getRealAssertionsEnd(), before) |
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// cannot be moved |
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// added [before, cur_size) |
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// can be modified |
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Assert(0 < assertionsToPreprocess->getRealAssertionsEnd()); |
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Assert(assertionsToPreprocess->getRealAssertionsEnd() <= before); |
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Assert(before < cur_size); |
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std::vector<Node> intoConjunction; |
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for (size_t i = before; i < cur_size; ++i) |
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{ |
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intoConjunction.push_back((*assertionsToPreprocess)[i]); |
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} |
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assertionsToPreprocess->resize(before); |
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size_t lastBeforeItes = assertionsToPreprocess->getRealAssertionsEnd() - 1; |
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intoConjunction.push_back((*assertionsToPreprocess)[lastBeforeItes]); |
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Node newLast = cvc5::util::NaryBuilder::mkAssoc(kind::AND, intoConjunction); |
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assertionsToPreprocess->replace(lastBeforeItes, newLast); |
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Assert(assertionsToPreprocess->size() == before); |
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} |
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} // namespace |
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/* -------------------------------------------------------------------------- */ |
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ITESimp::Statistics::Statistics() |
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: d_arithSubstitutionsAdded(smtStatisticsRegistry().registerInt( |
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"preprocessing::passes::ITESimp::ArithSubstitutionsAdded")) |
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{ |
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} |
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bool ITESimp::doneSimpITE(AssertionPipeline* assertionsToPreprocess) |
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{ |
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bool result = true; |
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bool simpDidALotOfWork = d_iteUtilities.simpIteDidALotOfWorkHeuristic(); |
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if (simpDidALotOfWork) |
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{ |
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if (options::compressItes()) |
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{ |
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result = d_iteUtilities.compress(assertionsToPreprocess); |
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} |
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if (result) |
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{ |
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// if false, don't bother to reclaim memory here. |
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NodeManager* nm = NodeManager::currentNM(); |
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if (nm->poolSize() >= options::zombieHuntThreshold()) |
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{ |
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Chat() << "..ite simplifier did quite a bit of work.. " |
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<< nm->poolSize() << endl; |
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Chat() << "....node manager contains " << nm->poolSize() |
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<< " nodes before cleanup" << endl; |
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d_iteUtilities.clear(); |
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Rewriter::clearCaches(); |
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nm->reclaimZombiesUntil(options::zombieHuntThreshold()); |
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Chat() << "....node manager contains " << nm->poolSize() |
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<< " nodes after cleanup" << endl; |
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} |
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} |
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} |
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// Do theory specific preprocessing passes |
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TheoryEngine* theory_engine = d_preprocContext->getTheoryEngine(); |
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if (theory_engine->getLogicInfo().isTheoryEnabled(theory::THEORY_ARITH) |
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&& !options::incrementalSolving()) |
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{ |
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if (!simpDidALotOfWork) |
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{ |
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util::ContainsTermITEVisitor& contains = |
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*(d_iteUtilities.getContainsVisitor()); |
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arith::ArithIteUtils aiteu(contains, |
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d_preprocContext->getUserContext(), |
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d_preprocContext->getTopLevelSubstitutions().get()); |
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bool anyItes = false; |
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for (size_t i = 0, size = assertionsToPreprocess->size(); i < size; ++i) |
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{ |
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Node curr = (*assertionsToPreprocess)[i]; |
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if (contains.containsTermITE(curr)) |
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{ |
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anyItes = true; |
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Node res = aiteu.reduceVariablesInItes(curr); |
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Debug("arith::ite::red") << "@ " << i << " ... " << curr << endl |
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<< " ->" << res << endl; |
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if (curr != res) |
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{ |
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Node more = aiteu.reduceConstantIteByGCD(res); |
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Debug("arith::ite::red") << " gcd->" << more << endl; |
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Node morer = Rewriter::rewrite(more); |
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assertionsToPreprocess->replace(i, morer); |
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} |
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} |
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} |
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if (!anyItes) |
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{ |
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unsigned prevSubCount = aiteu.getSubCount(); |
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aiteu.learnSubstitutions(assertionsToPreprocess->ref()); |
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if (prevSubCount < aiteu.getSubCount()) |
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{ |
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d_statistics.d_arithSubstitutionsAdded += |
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aiteu.getSubCount() - prevSubCount; |
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bool anySuccess = false; |
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for (size_t i = 0, N = assertionsToPreprocess->size(); i < N; ++i) |
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{ |
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Node curr = (*assertionsToPreprocess)[i]; |
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Node next = Rewriter::rewrite(aiteu.applySubstitutions(curr)); |
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Node res = aiteu.reduceVariablesInItes(next); |
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Debug("arith::ite::red") << "@ " << i << " ... " << next << endl |
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<< " ->" << res << endl; |
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Node more = aiteu.reduceConstantIteByGCD(res); |
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Debug("arith::ite::red") << " gcd->" << more << endl; |
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if (more != next) |
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{ |
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anySuccess = true; |
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break; |
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} |
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} |
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for (size_t i = 0, N = assertionsToPreprocess->size(); |
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anySuccess && i < N; |
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++i) |
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{ |
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Node curr = (*assertionsToPreprocess)[i]; |
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Node next = Rewriter::rewrite(aiteu.applySubstitutions(curr)); |
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Node res = aiteu.reduceVariablesInItes(next); |
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Debug("arith::ite::red") << "@ " << i << " ... " << next << endl |
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<< " ->" << res << endl; |
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Node more = aiteu.reduceConstantIteByGCD(res); |
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Debug("arith::ite::red") << " gcd->" << more << endl; |
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Node morer = Rewriter::rewrite(more); |
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assertionsToPreprocess->replace(i, morer); |
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} |
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} |
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} |
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} |
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} |
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return result; |
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} |
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/* -------------------------------------------------------------------------- */ |
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ITESimp::ITESimp(PreprocessingPassContext* preprocContext) |
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: PreprocessingPass(preprocContext, "ite-simp") |
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{ |
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} |
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PreprocessingPassResult ITESimp::applyInternal( |
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AssertionPipeline* assertionsToPreprocess) |
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{ |
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d_preprocContext->spendResource(Resource::PreprocessStep); |
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size_t nasserts = assertionsToPreprocess->size(); |
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for (size_t i = 0; i < nasserts; ++i) |
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{ |
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d_preprocContext->spendResource(Resource::PreprocessStep); |
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Node simp = simpITE(&d_iteUtilities, (*assertionsToPreprocess)[i]); |
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assertionsToPreprocess->replace(i, simp); |
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if (simp.isConst() && !simp.getConst<bool>()) |
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{ |
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return PreprocessingPassResult::CONFLICT; |
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} |
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} |
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bool done = doneSimpITE(assertionsToPreprocess); |
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if (nasserts < assertionsToPreprocess->size()) |
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{ |
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compressBeforeRealAssertions(assertionsToPreprocess, nasserts); |
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} |
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return done ? PreprocessingPassResult::NO_CONFLICT |
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: PreprocessingPassResult::CONFLICT; |
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} |
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/* -------------------------------------------------------------------------- */ |
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} // namespace passes |
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} // namespace preprocessing |
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} // namespace cvc5 |