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/****************************************************************************** |
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* Top contributors (to current version): |
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* Andrew Reynolds, Yoni Zohar, Aina Niemetz |
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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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* Implementation of global_negate. |
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*/ |
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#include "preprocessing/passes/global_negate.h" |
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#include <vector> |
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#include "expr/node.h" |
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#include "preprocessing/assertion_pipeline.h" |
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#include "theory/rewriter.h" |
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using namespace std; |
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using namespace cvc5::kind; |
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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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Node GlobalNegate::simplify(const std::vector<Node>& assertions, |
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NodeManager* nm) |
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{ |
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Assert(!assertions.empty()); |
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Trace("cegqi-gn") << "Global negate : " << std::endl; |
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// collect free variables in all assertions |
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std::vector<Node> free_vars; |
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std::vector<TNode> visit; |
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std::unordered_set<TNode> visited; |
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for (const Node& as : assertions) |
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{ |
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Trace("cegqi-gn") << " " << as << std::endl; |
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TNode cur = as; |
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// compute free variables |
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visit.push_back(cur); |
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do |
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{ |
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cur = visit.back(); |
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visit.pop_back(); |
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if (visited.find(cur) == visited.end()) |
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{ |
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visited.insert(cur); |
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if (cur.isVar() && cur.getKind() != BOUND_VARIABLE) |
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{ |
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free_vars.push_back(cur); |
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} |
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for (const TNode& cn : cur) |
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{ |
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visit.push_back(cn); |
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} |
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} |
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} while (!visit.empty()); |
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} |
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Node body; |
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if (assertions.size() == 1) |
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{ |
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body = assertions[0]; |
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} |
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else |
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{ |
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body = nm->mkNode(AND, assertions); |
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} |
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// do the negation |
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body = body.negate(); |
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if (!free_vars.empty()) |
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{ |
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std::vector<Node> bvs; |
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for (const Node& v : free_vars) |
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{ |
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Node bv = nm->mkBoundVar(v.getType()); |
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bvs.push_back(bv); |
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} |
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body = body.substitute( |
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free_vars.begin(), free_vars.end(), bvs.begin(), bvs.end()); |
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Node bvl = nm->mkNode(BOUND_VAR_LIST, bvs); |
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body = nm->mkNode(FORALL, bvl, body); |
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} |
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Trace("cegqi-gn-debug") << "...got (pre-rewrite) : " << body << std::endl; |
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body = Rewriter::rewrite(body); |
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Trace("cegqi-gn") << "...got (post-rewrite) : " << body << std::endl; |
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return body; |
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} |
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GlobalNegate::GlobalNegate(PreprocessingPassContext* preprocContext) |
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: PreprocessingPass(preprocContext, "global-negate"){}; |
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PreprocessingPassResult GlobalNegate::applyInternal( |
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AssertionPipeline* assertionsToPreprocess) |
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{ |
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NodeManager* nm = NodeManager::currentNM(); |
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Node simplifiedNode = simplify(assertionsToPreprocess->ref(), nm); |
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Node trueNode = nm->mkConst(true); |
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for (unsigned i = 0, size = assertionsToPreprocess->size(); i < size; ++i) |
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{ |
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if (i == 0) |
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{ |
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assertionsToPreprocess->replace(i, simplifiedNode); |
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} |
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else |
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{ |
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assertionsToPreprocess->replace(i, trueNode); |
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} |
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} |
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return PreprocessingPassResult::NO_CONFLICT; |
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} |
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} // namespace passes |
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} // namespace preprocessing |
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} // namespace cvc5 |