src/theory/bv/bv_subtheory_core.cpp

   1 /*********************                                                        */
   2 /*! \file bv_subtheory_eq.cpp
   3  ** \verbatim
   4  ** Original author: dejan
   5  ** Major contributors: none
   6  ** Minor contributors (to current version): lianah
   7  ** This file is part of the CVC4 prototype.
   8  ** Copyright (c) 2009-2012  New York University and The University of Iowa
   9  ** See the file COPYING in the top-level source directory for licensing
  10  ** information.\endverbatim
  11  **
  12  ** \brief Algebraic solver.
  13  **
  14  ** Algebraic solver.
  15  **/
  16
  17 #include "theory/bv/bv_subtheory_eq.h"
  18
  19 #include "theory/bv/theory_bv.h"
  20 #include "theory/bv/theory_bv_utils.h"
  21 #include "theory/bv/slicer.h"
  22 #include "theory/model.h"
  23
  24 using namespace std;
  25 using namespace CVC4;
  26 using namespace CVC4::context;
  27 using namespace CVC4::theory;
  28 using namespace CVC4::theory::bv;
  29 using namespace CVC4::theory::bv::utils;
  30
  31 CoreSolver::CoreSolver(context::Context* c, TheoryBV* bv, Slicer* slicer)
  32   : SubtheorySolver(c, bv),
  33     d_notify(*this),
  34     d_equalityEngine(d_notify, c, "theory::bv::TheoryBV"),
  35     d_assertions(c),
  36     d_normalFormCache(),
  37     d_slicer(slicer),
  38     d_isCoreTheory(c, true)
  39 {
  40   if (d_useEqualityEngine) {
  41
  42     // The kinds we are treating as function application in congruence
  43     d_equalityEngine.addFunctionKind(kind::BITVECTOR_CONCAT);
  44     //    d_equalityEngine.addFunctionKind(kind::BITVECTOR_AND);
  45     //    d_equalityEngine.addFunctionKind(kind::BITVECTOR_OR);
  46     //    d_equalityEngine.addFunctionKind(kind::BITVECTOR_XOR);
  47     //    d_equalityEngine.addFunctionKind(kind::BITVECTOR_NOT);
  48     //    d_equalityEngine.addFunctionKind(kind::BITVECTOR_NAND);
  49     //    d_equalityEngine.addFunctionKind(kind::BITVECTOR_NOR);
  50     //    d_equalityEngine.addFunctionKind(kind::BITVECTOR_XNOR);
  51     //    d_equalityEngine.addFunctionKind(kind::BITVECTOR_COMP);
  52     d_equalityEngine.addFunctionKind(kind::BITVECTOR_MULT);
  53     d_equalityEngine.addFunctionKind(kind::BITVECTOR_PLUS);
  54     //    d_equalityEngine.addFunctionKind(kind::BITVECTOR_SUB);
  55     //    d_equalityEngine.addFunctionKind(kind::BITVECTOR_NEG);
  56     //    d_equalityEngine.addFunctionKind(kind::BITVECTOR_UDIV);
  57     //    d_equalityEngine.addFunctionKind(kind::BITVECTOR_UREM);
  58     //    d_equalityEngine.addFunctionKind(kind::BITVECTOR_SDIV);
  59     //    d_equalityEngine.addFunctionKind(kind::BITVECTOR_SREM);
  60     //    d_equalityEngine.addFunctionKind(kind::BITVECTOR_SMOD);
  61     //    d_equalityEngine.addFunctionKind(kind::BITVECTOR_SHL);
  62     //    d_equalityEngine.addFunctionKind(kind::BITVECTOR_LSHR);
  63     //    d_equalityEngine.addFunctionKind(kind::BITVECTOR_ASHR);
  64     //    d_equalityEngine.addFunctionKind(kind::BITVECTOR_ULT);
  65     //    d_equalityEngine.addFunctionKind(kind::BITVECTOR_ULE);
  66     //    d_equalityEngine.addFunctionKind(kind::BITVECTOR_UGT);
  67     //    d_equalityEngine.addFunctionKind(kind::BITVECTOR_UGE);
  68     //    d_equalityEngine.addFunctionKind(kind::BITVECTOR_SLT);
  69     //    d_equalityEngine.addFunctionKind(kind::BITVECTOR_SLE);
  70     //    d_equalityEngine.addFunctionKind(kind::BITVECTOR_SGT);
  71     //    d_equalityEngine.addFunctionKind(kind::BITVECTOR_SGE);
  72   }
  73 }
  74
  75 void CoreSolver::setMasterEqualityEngine(eq::EqualityEngine* eq) {
  76   d_equalityEngine.setMasterEqualityEngine(eq);
  77 }
  78
  79 void CoreSolver::preRegister(TNode node) {
  80   if (!d_useEqualityEngine)
  81     return;
  82
  83   if (node.getKind() == kind::EQUAL) {
  84       d_equalityEngine.addTriggerEquality(node);
  85   } else {
  86     d_equalityEngine.addTerm(node);
  87   }
  88 }
  89
  90
  91 void CoreSolver::explain(TNode literal, std::vector<TNode>& assumptions) {
  92   bool polarity = literal.getKind() != kind::NOT;
  93   TNode atom = polarity ? literal : literal[0];
  94   if (atom.getKind() == kind::EQUAL) {
  95     d_equalityEngine.explainEquality(atom[0], atom[1], polarity, assumptions);
  96   } else {
  97     d_equalityEngine.explainPredicate(atom, polarity, assumptions);
  98   }
  99 }
 100
 101 Node CoreSolver::getBaseDecomposition(TNode a) {
 102   if (d_normalFormCache.find(a) != d_normalFormCache.end()) {
 103     return d_normalFormCache[a];
 104   }
 105
 106   // otherwise we must compute the normal form
 107   std::vector<Node> a_decomp;
 108   d_slicer->getBaseDecomposition(a, a_decomp);
 109   Node new_a = utils::mkConcat(a_decomp);
 110   d_normalFormCache[a] = new_a;
 111   return new_a;
 112 }
 113
 114 bool CoreSolver::decomposeFact(TNode fact) {
 115   Debug("bv-slicer") << "CoreSolver::decomposeFact fact=" << fact << endl;
 116   // FIXME: are this the right things to assert?
 117   // assert decompositions since the equality engine does not know the semantics of
 118   // concat:
 119   //   a == a_1 concat ... concat a_k
 120   //   b == b_1 concat ... concat b_k
 121   TNode eq = fact.getKind() == kind::NOT? fact[0] : fact;
 122
 123   TNode a = eq[0];
 124   TNode b = eq[1];
 125   Node new_a = getBaseDecomposition(a);
 126   Node new_b = getBaseDecomposition(b);
 127
 128   Assert (utils::getSize(new_a) == utils::getSize(new_b) &&
 129           utils::getSize(new_a) == utils::getSize(a));
 130
 131   NodeManager* nm = NodeManager::currentNM();
 132   Node a_eq_new_a = nm->mkNode(kind::EQUAL, a, new_a);
 133   Node b_eq_new_b = nm->mkNode(kind::EQUAL, b, new_b);
 134
 135   bool ok = true;
 136   ok = assertFact(a_eq_new_a, utils::mkTrue());
 137   if (!ok) return false;
 138   ok = assertFact(b_eq_new_b, utils::mkTrue());
 139   if (!ok) return false;
 140   ok = assertFact(fact, fact);
 141   if (!ok) return false;
 142
 143   if (fact.getKind() == kind::EQUAL) {
 144     // assert the individual equalities as well
 145     //    a_i == b_i
 146     if (new_a.getKind() == kind::BITVECTOR_CONCAT &&
 147         new_b.getKind() == kind::BITVECTOR_CONCAT) {
 148
 149       Assert (new_a.getNumChildren() == new_b.getNumChildren());
 150       for (unsigned i = 0; i < new_a.getNumChildren(); ++i) {
 151         Node eq_i = nm->mkNode(kind::EQUAL, new_a[i], new_b[i]);
 152         ok = assertFact(eq_i, fact);
 153         if (!ok) return false;
 154       }
 155     }
 156   }
 157   return true;
 158 }
 159
 160 bool CoreSolver::addAssertions(const std::vector<TNode>& assertions, Theory::Effort e) {
 161   Trace("bitvector::core") << "CoreSolver::addAssertions \n";
 162   Assert (!d_bv->inConflict());
 163
 164   bool ok = true;
 165   std::vector<Node> core_eqs;
 166   for (unsigned i = 0; i < assertions.size(); ++i) {
 167     TNode fact = assertions[i];
 168
 169     // update whether we are in the core fragment
 170     // FIXME: move isCoreTerm into CoreSolver
 171     if (d_isCoreTheory && !d_slicer->isCoreTerm(fact)) {
 172       d_isCoreTheory = false;
 173     }
 174
 175     // only reason about equalities
 176     // FIXME: should we slice when we have the terms in inequalities?
 177     if (fact.getKind() == kind::EQUAL || (fact.getKind() == kind::NOT && fact[0].getKind() == kind::EQUAL)) {
 178       ok = decomposeFact(fact);
 179     } else {
 180       ok = assertFact(fact, fact);
 181     }
 182     if (!ok)
 183       return false;
 184   }
 185
 186   return true;
 187 }
 188
 189 bool CoreSolver::assertFact(TNode fact, TNode reason) {
 190   Debug("bv-slicer") << "CoreSolver::assertFact fact=" << fact << endl;
 191   Debug("bv-slicer") << "                     reason=" << reason << endl;
 192   // Notify the equality engine
 193   if (d_useEqualityEngine && !d_bv->inConflict() && !d_bv->propagatedBy(fact, SUB_CORE) ) {
 194     Trace("bitvector::core") << "     (assert " << fact << ")\n";
 195     //d_assertions.push_back(fact);
 196     bool negated = fact.getKind() == kind::NOT;
 197     TNode predicate = negated ? fact[0] : fact;
 198     if (predicate.getKind() == kind::EQUAL) {
 199       if (negated) {
 200         // dis-equality
 201         d_equalityEngine.assertEquality(predicate, false, reason);
 202       } else {
 203         // equality
 204         d_equalityEngine.assertEquality(predicate, true, reason);
 205       }
 206     } else {
 207       // Adding predicate if the congruence over it is turned on
 208       if (d_equalityEngine.isFunctionKind(predicate.getKind())) {
 209         d_equalityEngine.assertPredicate(predicate, !negated, reason);
 210       }
 211     }
 212   }
 213
 214   // checking for a conflict
 215   if (d_bv->inConflict()) {
 216     return false;
 217   }
 218   return true;
 219 }
 220
 221 bool CoreSolver::NotifyClass::eqNotifyTriggerEquality(TNode equality, bool value) {
 222   BVDebug("bitvector::core") << "NotifyClass::eqNotifyTriggerEquality(" << equality << ", " << (value ? "true" : "false" )<< ")" << std::endl;
 223   if (value) {
 224     return d_solver.storePropagation(equality);
 225   } else {
 226     return d_solver.storePropagation(equality.notNode());
 227   }
 228 }
 229
 230 bool CoreSolver::NotifyClass::eqNotifyTriggerPredicate(TNode predicate, bool value) {
 231   BVDebug("bitvector::core") << "NotifyClass::eqNotifyTriggerPredicate(" << predicate << ", " << (value ? "true" : "false" ) << ")" << std::endl;
 232   if (value) {
 233     return d_solver.storePropagation(predicate);
 234   } else {
 235     return d_solver.storePropagation(predicate.notNode());
 236   }
 237 }
 238
 239 bool CoreSolver::NotifyClass::eqNotifyTriggerTermEquality(TheoryId tag, TNode t1, TNode t2, bool value) {
 240   Debug("bitvector::core") << "NotifyClass::eqNotifyTriggerTermMerge(" << t1 << ", " << t2 << ")" << std::endl;
 241   if (value) {
 242     return d_solver.storePropagation(t1.eqNode(t2));
 243   } else {
 244     return d_solver.storePropagation(t1.eqNode(t2).notNode());
 245   }
 246 }
 247
 248 void CoreSolver::NotifyClass::eqNotifyConstantTermMerge(TNode t1, TNode t2) {
 249   d_solver.conflict(t1, t2);
 250 }
 251
 252 bool CoreSolver::storePropagation(TNode literal) {
 253   return d_bv->storePropagation(literal, SUB_CORE);
 254 }
 255
 256 void CoreSolver::conflict(TNode a, TNode b) {
 257   std::vector<TNode> assumptions;
 258   d_equalityEngine.explainEquality(a, b, true, assumptions);
 259   d_bv->setConflict(mkAnd(assumptions));
 260 }
 261
 262 void CoreSolver::collectModelInfo(TheoryModel* m) {
 263   if (Debug.isOn("bitvector-model")) {
 264     context::CDList<TNode>::const_iterator it = d_assertions.begin();
 265     for (; it!= d_assertions.end(); ++it) {
 266       Debug("bitvector-model") << "CoreSolver::collectModelInfo (assert "
 267                                << *it << ")\n";
 268     }
 269   }
 270   set<Node> termSet;
 271   d_bv->computeRelevantTerms(termSet);
 272   m->assertEqualityEngine(&d_equalityEngine, &termSet);
 273 }