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Diffstat (limited to 'src/smt_util/ite_removal.cpp')
| -rw-r--r-- | src/smt_util/ite_removal.cpp | 192 |
1 files changed, 192 insertions, 0 deletions
diff --git a/src/smt_util/ite_removal.cpp b/src/smt_util/ite_removal.cpp new file mode 100644 index 000000000..0d1c7b61e --- /dev/null +++ b/src/smt_util/ite_removal.cpp @@ -0,0 +1,192 @@ +/********************* */ +/*! \file ite_removal.cpp + ** \verbatim + ** Original author: Dejan Jovanovic + ** Major contributors: Tim King, Morgan Deters + ** Minor contributors (to current version): Kshitij Bansal, Andrew Reynolds, Clark Barrett + ** This file is part of the CVC4 project. + ** Copyright (c) 2009-2014 New York University and The University of Iowa + ** See the file COPYING in the top-level source directory for licensing + ** information.\endverbatim + ** + ** \brief Removal of term ITEs + ** + ** Removal of term ITEs. + **/ +#include "smt_util/ite_removal.h" + +#include <vector> + +#include "proof/proof_manager.h" +#include "smt_util/command.h" +#include "theory/ite_utilities.h" + +using namespace CVC4; +using namespace std; + +namespace CVC4 { + +RemoveITE::RemoveITE(context::UserContext* u) + : d_iteCache(u) +{ + d_containsVisitor = new theory::ContainsTermITEVisitor(); +} + +RemoveITE::~RemoveITE(){ + delete d_containsVisitor; +} + +void RemoveITE::garbageCollect(){ + d_containsVisitor->garbageCollect(); +} + +theory::ContainsTermITEVisitor* RemoveITE::getContainsVisitor() { + return d_containsVisitor; +} + +size_t RemoveITE::collectedCacheSizes() const{ + return d_containsVisitor->cache_size() + d_iteCache.size(); +} + +void RemoveITE::run(std::vector<Node>& output, IteSkolemMap& iteSkolemMap, bool reportDeps) +{ + size_t n = output.size(); + for (unsigned i = 0, i_end = output.size(); i < i_end; ++ i) { + // Do this in two steps to avoid Node problems(?) + // Appears related to bug 512, splitting this into two lines + // fixes the bug on clang on Mac OS + Node itesRemoved = run(output[i], output, iteSkolemMap, false); + // In some calling contexts, not necessary to report dependence information. + if(reportDeps && options::unsatCores()) { + // new assertions have a dependence on the node + PROOF( ProofManager::currentPM()->addDependence(itesRemoved, output[i]); ) + while(n < output.size()) { + PROOF( ProofManager::currentPM()->addDependence(output[n], output[i]); ) + ++n; + } + } + output[i] = itesRemoved; + } +} + +bool RemoveITE::containsTermITE(TNode e) const { + return d_containsVisitor->containsTermITE(e); +} + +Node RemoveITE::run(TNode node, std::vector<Node>& output, + IteSkolemMap& iteSkolemMap, bool inQuant) { + // Current node + Debug("ite") << "removeITEs(" << node << ")" << endl; + + if(node.isVar() || node.isConst() || + (options::biasedITERemoval() && !containsTermITE(node))){ + return Node(node); + } + + // The result may be cached already + std::pair<Node, bool> cacheKey(node, inQuant); + NodeManager *nodeManager = NodeManager::currentNM(); + ITECache::const_iterator i = d_iteCache.find(cacheKey); + if(i != d_iteCache.end()) { + Node cached = (*i).second; + Debug("ite") << "removeITEs: in-cache: " << cached << endl; + return cached.isNull() ? Node(node) : cached; + } + + // Remember that we're inside a quantifier + if(node.getKind() == kind::FORALL || node.getKind() == kind::EXISTS) { + inQuant = true; + } + + // If an ITE replace it + if(node.getKind() == kind::ITE) { + TypeNode nodeType = node.getType(); + if(!nodeType.isBoolean() && (!inQuant || !node.hasBoundVar())) { + Node skolem; + // Make the skolem to represent the ITE + skolem = nodeManager->mkSkolem("termITE", nodeType, "a variable introduced due to term-level ITE removal"); + + // The new assertion + Node newAssertion = + nodeManager->mkNode(kind::ITE, node[0], skolem.eqNode(node[1]), + skolem.eqNode(node[2])); + Debug("ite") << "removeITEs(" << node << ") => " << newAssertion << endl; + + // Attach the skolem + d_iteCache.insert(cacheKey, skolem); + + // Remove ITEs from the new assertion, rewrite it and push it to the output + newAssertion = run(newAssertion, output, iteSkolemMap, inQuant); + + iteSkolemMap[skolem] = output.size(); + output.push_back(newAssertion); + + // The representation is now the skolem + return skolem; + } + } + + // If not an ITE, go deep + vector<Node> newChildren; + bool somethingChanged = false; + if(node.getMetaKind() == kind::metakind::PARAMETERIZED) { + newChildren.push_back(node.getOperator()); + } + // Remove the ITEs from the children + for(TNode::const_iterator it = node.begin(), end = node.end(); it != end; ++it) { + Node newChild = run(*it, output, iteSkolemMap, inQuant); + somethingChanged |= (newChild != *it); + newChildren.push_back(newChild); + } + + // If changes, we rewrite + if(somethingChanged) { + Node cached = nodeManager->mkNode(node.getKind(), newChildren); + d_iteCache.insert(cacheKey, cached); + return cached; + } else { + d_iteCache.insert(cacheKey, Node::null()); + return node; + } +} + +Node RemoveITE::replace(TNode node, bool inQuant) const { + if(node.isVar() || node.isConst() || + (options::biasedITERemoval() && !containsTermITE(node))){ + return Node(node); + } + + // Check the cache + NodeManager *nodeManager = NodeManager::currentNM(); + ITECache::const_iterator i = d_iteCache.find(make_pair(node, inQuant)); + if(i != d_iteCache.end()) { + Node cached = (*i).second; + return cached.isNull() ? Node(node) : cached; + } + + // Remember that we're inside a quantifier + if(node.getKind() == kind::FORALL || node.getKind() == kind::EXISTS) { + inQuant = true; + } + + vector<Node> newChildren; + bool somethingChanged = false; + if(node.getMetaKind() == kind::metakind::PARAMETERIZED) { + newChildren.push_back(node.getOperator()); + } + // Replace in children + for(TNode::const_iterator it = node.begin(), end = node.end(); it != end; ++it) { + Node newChild = replace(*it, inQuant); + somethingChanged |= (newChild != *it); + newChildren.push_back(newChild); + } + + // If changes, we rewrite + if(somethingChanged) { + return nodeManager->mkNode(node.getKind(), newChildren); + } else { + return node; + } +} + +}/* CVC4 namespace */ |