src/theory/bv/theory_bv.cpp

   1 /*********************                                                        */
   2 /*! \file theory_bv.cpp
   3  ** \verbatim
   4  ** Original author: Dejan Jovanovic
   5  ** Major contributors: Liana Hadarean
   6  ** Minor contributors (to current version): Tim King, Kshitij Bansal, Clark Barrett, Andrew Reynolds, Morgan Deters, Martin Brain <>
   7  ** This file is part of the CVC4 project.
   8  ** Copyright (c) 2009-2014  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  ** [[ Add lengthier description here ]]
  13  ** \todo document this file
  14 **/
  15
  16 #include "smt/options.h"
  17 #include "theory/bv/theory_bv.h"
  18 #include "theory/bv/theory_bv_utils.h"
  19 #include "theory/bv/slicer.h"
  20 #include "theory/valuation.h"
  21 #include "theory/bv/options.h"
  22 #include "theory/bv/theory_bv_rewrite_rules_normalization.h"
  23 #include "theory/bv/theory_bv_rewrite_rules_simplification.h"
  24 #include "theory/bv/bv_subtheory_core.h"
  25 #include "theory/bv/bv_subtheory_inequality.h"
  26 #include "theory/bv/bv_subtheory_algebraic.h"
  27 #include "theory/bv/bv_subtheory_bitblast.h"
  28 #include "theory/bv/bv_eager_solver.h"
  29 #include "theory/bv/theory_bv_rewriter.h"
  30 #include "theory/theory_model.h"
  31 #include "theory/bv/abstraction.h"
  32
  33 using namespace CVC4;
  34 using namespace CVC4::theory;
  35 using namespace CVC4::theory::bv;
  36 using namespace CVC4::context;
  37
  38 using namespace std;
  39 using namespace CVC4::theory::bv::utils;
  40
  41 TheoryBV::TheoryBV(context::Context* c, context::UserContext* u, OutputChannel& out, Valuation valuation, const LogicInfo& logicInfo)
  42   : Theory(THEORY_BV, c, u, out, valuation, logicInfo),
  43     d_context(c),
  44     d_alreadyPropagatedSet(c),
  45     d_sharedTermsSet(c),
  46     d_subtheories(),
  47     d_subtheoryMap(),
  48     d_statistics(),
  49     d_staticLearnCache(),
  50     d_lemmasAdded(c, false),
  51     d_conflict(c, false),
  52     d_invalidateModelCache(c, true),
  53     d_literalsToPropagate(c),
  54     d_literalsToPropagateIndex(c, 0),
  55     d_propagatedBy(c),
  56     d_eagerSolver(NULL),
  57     d_abstractionModule(new AbstractionModule()),
  58     d_isCoreTheory(false),
  59     d_calledPreregister(false)
  60 {
  61
  62   if (options::bitblastMode() == theory::bv::BITBLAST_MODE_EAGER) {
  63     d_eagerSolver = new EagerBitblastSolver(this);
  64     return;
  65   }
  66
  67   if (options::bitvectorEqualitySolver()) {
  68     SubtheorySolver* core_solver = new CoreSolver(c, this);
  69     d_subtheories.push_back(core_solver);
  70     d_subtheoryMap[SUB_CORE] = core_solver;
  71   }
  72
  73   if (options::bitvectorInequalitySolver()) {
  74     SubtheorySolver* ineq_solver = new InequalitySolver(c, this);
  75     d_subtheories.push_back(ineq_solver);
  76     d_subtheoryMap[SUB_INEQUALITY] = ineq_solver;
  77   }
  78
  79   if (options::bitvectorAlgebraicSolver()) {
  80     SubtheorySolver* alg_solver = new AlgebraicSolver(c, this);
  81     d_subtheories.push_back(alg_solver);
  82     d_subtheoryMap[SUB_ALGEBRAIC] = alg_solver;
  83   }
  84
  85   BitblastSolver* bb_solver = new BitblastSolver(c, this);
  86   if (options::bvAbstraction()) {
  87     bb_solver->setAbstraction(d_abstractionModule);
  88   }
  89   d_subtheories.push_back(bb_solver);
  90   d_subtheoryMap[SUB_BITBLAST] = bb_solver;
  91 }
  92
  93
  94 TheoryBV::~TheoryBV() {
  95   for (unsigned i = 0; i < d_subtheories.size(); ++i) {
  96     delete d_subtheories[i];
  97   }
  98 }
  99
 100 void TheoryBV::setMasterEqualityEngine(eq::EqualityEngine* eq) {
 101   if (options::bitblastMode() == theory::bv::BITBLAST_MODE_EAGER) {
 102     return;
 103   }
 104   if (options::bitvectorEqualitySolver()) {
 105     dynamic_cast<CoreSolver*>(d_subtheoryMap[SUB_CORE])->setMasterEqualityEngine(eq);
 106   }
 107 }
 108
 109 TheoryBV::Statistics::Statistics():
 110   d_avgConflictSize("theory::bv::AvgBVConflictSize"),
 111   d_solveSubstitutions("theory::bv::NumberOfSolveSubstitutions", 0),
 112   d_solveTimer("theory::bv::solveTimer"),
 113   d_numCallsToCheckFullEffort("theory::bv::NumberOfFullCheckCalls", 0),
 114   d_numCallsToCheckStandardEffort("theory::bv::NumberOfStandardCheckCalls", 0),
 115   d_weightComputationTimer("theory::bv::weightComputationTimer"),
 116   d_numMultSlice("theory::bv::NumMultSliceApplied", 0)
 117 {
 118   StatisticsRegistry::registerStat(&d_avgConflictSize);
 119   StatisticsRegistry::registerStat(&d_solveSubstitutions);
 120   StatisticsRegistry::registerStat(&d_solveTimer);
 121   StatisticsRegistry::registerStat(&d_numCallsToCheckFullEffort);
 122   StatisticsRegistry::registerStat(&d_numCallsToCheckStandardEffort);
 123   StatisticsRegistry::registerStat(&d_weightComputationTimer);
 124   StatisticsRegistry::registerStat(&d_numMultSlice);
 125 }
 126
 127 TheoryBV::Statistics::~Statistics() {
 128   StatisticsRegistry::unregisterStat(&d_avgConflictSize);
 129   StatisticsRegistry::unregisterStat(&d_solveSubstitutions);
 130   StatisticsRegistry::unregisterStat(&d_solveTimer);
 131   StatisticsRegistry::unregisterStat(&d_numCallsToCheckFullEffort);
 132   StatisticsRegistry::unregisterStat(&d_numCallsToCheckStandardEffort);
 133   StatisticsRegistry::unregisterStat(&d_weightComputationTimer);
 134   StatisticsRegistry::unregisterStat(&d_numMultSlice);
 135 }
 136
 137 Node TheoryBV::getBVDivByZero(Kind k, unsigned width) {
 138   NodeManager* nm = NodeManager::currentNM();
 139   if (k == kind::BITVECTOR_UDIV) {
 140     if (d_BVDivByZero.find(width) == d_BVDivByZero.end()) {
 141       // lazily create the function symbols
 142       ostringstream os;
 143       os << "BVUDivByZero_" << width;
 144       Node divByZero = nm->mkSkolem(os.str(),
 145                                     nm->mkFunctionType(nm->mkBitVectorType(width), nm->mkBitVectorType(width)),
 146                                     "partial bvudiv", NodeManager::SKOLEM_EXACT_NAME);
 147       d_BVDivByZero[width] = divByZero;
 148     }
 149     return d_BVDivByZero[width];
 150   }
 151   else if (k == kind::BITVECTOR_UREM) {
 152     if (d_BVRemByZero.find(width) == d_BVRemByZero.end()) {
 153       ostringstream os;
 154       os << "BVURemByZero_" << width;
 155       Node divByZero = nm->mkSkolem(os.str(),
 156                                     nm->mkFunctionType(nm->mkBitVectorType(width), nm->mkBitVectorType(width)),
 157                                     "partial bvurem", NodeManager::SKOLEM_EXACT_NAME);
 158       d_BVRemByZero[width] = divByZero;
 159     }
 160     return d_BVRemByZero[width];
 161   }
 162
 163   Unreachable();
 164 }
 165
 166
 167 void TheoryBV::collectNumerators(TNode term, TNodeSet& seen) {
 168   if (seen.find(term) != seen.end())
 169     return;
 170   if (term.getKind() == kind::BITVECTOR_ACKERMANIZE_UDIV) {
 171     unsigned size = utils::getSize(term[0]);
 172     if (d_BVDivByZeroAckerman.find(size) == d_BVDivByZeroAckerman.end()) {
 173       d_BVDivByZeroAckerman[size] = TNodeSet();
 174     }
 175     d_BVDivByZeroAckerman[size].insert(term[0]);
 176     seen.insert(term);
 177   } else if (term.getKind() == kind::BITVECTOR_ACKERMANIZE_UREM) {
 178     unsigned size = utils::getSize(term[0]);
 179     if (d_BVRemByZeroAckerman.find(size) == d_BVRemByZeroAckerman.end()) {
 180       d_BVRemByZeroAckerman[size] = TNodeSet();
 181     }
 182     d_BVRemByZeroAckerman[size].insert(term[0]);
 183     seen.insert(term);
 184   }
 185   for (unsigned i = 0; i < term.getNumChildren(); ++i) {
 186     collectNumerators(term[i], seen);
 187   }
 188   seen.insert(term);
 189 }
 190
 191 void TheoryBV::mkAckermanizationAsssertions(std::vector<Node>& assertions) {
 192   Debug("bv-ackermanize") << "TheoryBV::mkAckermanizationAsssertions\n";
 193
 194   Assert(options::bitblastMode() == theory::bv::BITBLAST_MODE_EAGER);
 195   AlwaysAssert(!options::incrementalSolving());
 196   TNodeSet seen;
 197   for (unsigned i = 0; i < assertions.size(); ++i) {
 198     collectNumerators(assertions[i], seen);
 199   }
 200
 201   // process division UF
 202   Debug("bv-ackermanize") << "Process division UF...\n";
 203   for (WidthToNumerators::const_iterator it = d_BVDivByZeroAckerman.begin(); it != d_BVDivByZeroAckerman.end(); ++it) {
 204     const TNodeSet& numerators= it->second;
 205     for (TNodeSet::const_iterator i = numerators.begin(); i != numerators.end(); ++i) {
 206       TNodeSet::const_iterator j = i;
 207       j++;
 208       for (; j != numerators.end(); ++j) {
 209         TNode arg1 = *i;
 210         TNode arg2 = *j;
 211         TNode acker1 = utils::mkNode(kind::BITVECTOR_ACKERMANIZE_UDIV, arg1);
 212         TNode acker2 = utils::mkNode(kind::BITVECTOR_ACKERMANIZE_UDIV, arg2);
 213
 214         Node arg_eq = utils::mkNode(kind::EQUAL, arg1, arg2);
 215         Node acker_eq = utils::mkNode(kind::EQUAL, acker1, acker2);
 216         Node lemma = utils::mkNode(kind::IMPLIES, arg_eq, acker_eq);
 217         Debug("bv-ackermanize") << "  " << lemma << "\n";
 218         assertions.push_back(lemma);
 219       }
 220     }
 221   }
 222   // process remainder UF
 223   Debug("bv-ackermanize") << "Process remainder UF...\n";
 224   for (WidthToNumerators::const_iterator it = d_BVRemByZeroAckerman.begin(); it != d_BVRemByZeroAckerman.end(); ++it) {
 225     const TNodeSet& numerators= it->second;
 226     for (TNodeSet::const_iterator i = numerators.begin(); i != numerators.end(); ++i) {
 227       TNodeSet::const_iterator j = i;
 228       j++;
 229       for (; j != numerators.end(); ++j) {
 230         TNode arg1 = *i;
 231         TNode arg2 = *j;
 232         TNode acker1 = utils::mkNode(kind::BITVECTOR_ACKERMANIZE_UREM, arg1);
 233         TNode acker2 = utils::mkNode(kind::BITVECTOR_ACKERMANIZE_UREM, arg2);
 234
 235         Node arg_eq = utils::mkNode(kind::EQUAL, arg1, arg2);
 236         Node acker_eq = utils::mkNode(kind::EQUAL, acker1, acker2);
 237         Node lemma = utils::mkNode(kind::IMPLIES, arg_eq, acker_eq);
 238         Debug("bv-ackermanize") << "  " << lemma << "\n";
 239         assertions.push_back(lemma);
 240       }
 241     }
 242   }
 243 }
 244
 245 Node TheoryBV::expandDefinition(LogicRequest &logicRequest, Node node) {
 246   Debug("bitvector-expandDefinition") << "TheoryBV::expandDefinition(" << node << ")" << std::endl;
 247
 248   switch (node.getKind()) {
 249   case kind::BITVECTOR_SDIV:
 250   case kind::BITVECTOR_SREM:
 251   case kind::BITVECTOR_SMOD:
 252     return TheoryBVRewriter::eliminateBVSDiv(node);
 253     break;
 254
 255   case kind::BITVECTOR_UDIV:
 256   case kind::BITVECTOR_UREM: {
 257     NodeManager* nm = NodeManager::currentNM();
 258     unsigned width = node.getType().getBitVectorSize();
 259
 260     if (options::bitvectorDivByZeroConst()) {
 261       Kind kind = node.getKind() == kind::BITVECTOR_UDIV ? kind::BITVECTOR_UDIV_TOTAL : kind::BITVECTOR_UREM_TOTAL;
 262       return nm->mkNode(kind, node[0], node[1]);
 263     }
 264
 265     TNode num = node[0], den = node[1];
 266     Node den_eq_0 = nm->mkNode(kind::EQUAL, den, nm->mkConst(BitVector(width, Integer(0))));
 267     Node divTotalNumDen = nm->mkNode(node.getKind() == kind::BITVECTOR_UDIV ? kind::BITVECTOR_UDIV_TOTAL :
 268                                      kind::BITVECTOR_UREM_TOTAL, num, den);
 269
 270     if (options::bitblastMode() == theory::bv::BITBLAST_MODE_EAGER) {
 271       // Ackermanize UF if using eager bit-blasting
 272       Node ackerman_var = nm->mkNode(node.getKind() == kind::BITVECTOR_UDIV ? kind::BITVECTOR_ACKERMANIZE_UDIV : kind::BITVECTOR_ACKERMANIZE_UREM, num);
 273       node = nm->mkNode(kind::ITE, den_eq_0, ackerman_var, divTotalNumDen);
 274       return node;
 275     } else {
 276       Node divByZero = getBVDivByZero(node.getKind(), width);
 277       Node divByZeroNum = nm->mkNode(kind::APPLY_UF, divByZero, num);
 278       node = nm->mkNode(kind::ITE, den_eq_0, divByZeroNum, divTotalNumDen);
 279       logicRequest.widenLogic(THEORY_UF);
 280       return node;
 281     }
 282   }
 283     break;
 284
 285   default:
 286     return node;
 287     break;
 288   }
 289
 290   Unreachable();
 291 }
 292
 293
 294 void TheoryBV::preRegisterTerm(TNode node) {
 295   d_calledPreregister = true;
 296   Debug("bitvector-preregister") << "TheoryBV::preRegister(" << node << ")" << std::endl;
 297
 298   if (options::bitblastMode() == theory::bv::BITBLAST_MODE_EAGER) {
 299     // the aig bit-blaster option is set heuristically
 300     // if bv abstraction is not used
 301     if (!d_eagerSolver->isInitialized()) {
 302       d_eagerSolver->initialize();
 303     }
 304
 305     if (node.getKind() == kind::BITVECTOR_EAGER_ATOM) {
 306       Node formula = node[0];
 307       d_eagerSolver->assertFormula(formula);
 308     }
 309     // nothing to do for the other terms
 310     return;
 311   }
 312
 313   for (unsigned i = 0; i < d_subtheories.size(); ++i) {
 314     d_subtheories[i]->preRegister(node);
 315   }
 316 }
 317
 318 void TheoryBV::sendConflict() {
 319   Assert(d_conflict);
 320   if (d_conflictNode.isNull()) {
 321     return;
 322   } else {
 323     Debug("bitvector") << indent() << "TheoryBV::check(): conflict " << d_conflictNode;
 324     d_out->conflict(d_conflictNode);
 325     d_statistics.d_avgConflictSize.addEntry(d_conflictNode.getNumChildren());
 326     d_conflictNode = Node::null();
 327   }
 328 }
 329
 330 void TheoryBV::checkForLemma(TNode fact) {
 331   if (fact.getKind() == kind::EQUAL) {
 332     if (fact[0].getKind() == kind::BITVECTOR_UREM_TOTAL) {
 333       TNode urem = fact[0];
 334       TNode result = fact[1];
 335       TNode divisor = urem[1];
 336       Node result_ult_div = mkNode(kind::BITVECTOR_ULT, result, divisor);
 337       Node divisor_eq_0 = mkNode(kind::EQUAL,
 338                                  divisor,
 339                                  mkConst(BitVector(getSize(divisor), 0u)));
 340       Node split = utils::mkNode(kind::OR, divisor_eq_0, mkNode(kind::NOT, fact), result_ult_div);
 341       lemma(split);
 342     }
 343     if (fact[1].getKind() == kind::BITVECTOR_UREM_TOTAL) {
 344       TNode urem = fact[1];
 345       TNode result = fact[0];
 346       TNode divisor = urem[1];
 347       Node result_ult_div = mkNode(kind::BITVECTOR_ULT, result, divisor);
 348       Node divisor_eq_0 = mkNode(kind::EQUAL,
 349                                  divisor,
 350                                  mkConst(BitVector(getSize(divisor), 0u)));
 351       Node split = utils::mkNode(kind::OR, divisor_eq_0, mkNode(kind::NOT, fact), result_ult_div);
 352       lemma(split);
 353     }
 354   }
 355 }
 356
 357
 358 void TheoryBV::check(Effort e)
 359 {
 360   Debug("bitvector") << "TheoryBV::check(" << e << ")" << std::endl;
 361   // we may be getting new assertions so the model cache may not be sound
 362   d_invalidateModelCache.set(true);
 363   // if we are using the eager solver
 364   if (options::bitblastMode() == theory::bv::BITBLAST_MODE_EAGER) {
 365     // this can only happen on an empty benchmark
 366     if (!d_eagerSolver->isInitialized()) {
 367       d_eagerSolver->initialize();
 368     }
 369     if (!Theory::fullEffort(e))
 370       return;
 371
 372     std::vector<TNode> assertions;
 373     while (!done()) {
 374       TNode fact = get().assertion;
 375       Assert (fact.getKind() == kind::BITVECTOR_EAGER_ATOM);
 376       assertions.push_back(fact);
 377     }
 378     Assert (d_eagerSolver->hasAssertions(assertions));
 379
 380     bool ok = d_eagerSolver->checkSat();
 381     if (!ok) {
 382       if (assertions.size() == 1) {
 383         d_out->conflict(assertions[0]);
 384         return;
 385       }
 386       Node conflict = NodeManager::currentNM()->mkNode(kind::AND, assertions);
 387       d_out->conflict(conflict);
 388       return;
 389     }
 390     return;
 391   }
 392
 393
 394   if (Theory::fullEffort(e)) {
 395     ++(d_statistics.d_numCallsToCheckFullEffort);
 396   } else {
 397     ++(d_statistics.d_numCallsToCheckStandardEffort);
 398   }
 399   // if we are already in conflict just return the conflict
 400   if (inConflict()) {
 401     sendConflict();
 402     return;
 403   }
 404
 405   while (!done()) {
 406     TNode fact = get().assertion;
 407
 408     checkForLemma(fact);
 409
 410     for (unsigned i = 0; i < d_subtheories.size(); ++i) {
 411       d_subtheories[i]->assertFact(fact);
 412     }
 413   }
 414
 415   bool ok = true;
 416   bool complete = false;
 417   for (unsigned i = 0; i < d_subtheories.size(); ++i) {
 418     Assert (!inConflict());
 419     ok = d_subtheories[i]->check(e);
 420     complete = d_subtheories[i]->isComplete();
 421
 422     if (!ok) {
 423       // if we are in a conflict no need to check with other theories
 424       Assert (inConflict());
 425       sendConflict();
 426       return;
 427     }
 428     if (complete) {
 429       // if the last subtheory was complete we stop
 430       return;
 431     }
 432   }
 433 }
 434
 435 void TheoryBV::collectModelInfo( TheoryModel* m, bool fullModel ){
 436   Assert(!inConflict());
 437   if (options::bitblastMode() == theory::bv::BITBLAST_MODE_EAGER) {
 438     d_eagerSolver->collectModelInfo(m, fullModel);
 439   }
 440   for (unsigned i = 0; i < d_subtheories.size(); ++i) {
 441     if (d_subtheories[i]->isComplete()) {
 442       d_subtheories[i]->collectModelInfo(m, fullModel);
 443       return;
 444     }
 445   }
 446 }
 447
 448 Node TheoryBV::getModelValue(TNode var) {
 449   Assert(!inConflict());
 450   for (unsigned i = 0; i < d_subtheories.size(); ++i) {
 451     if (d_subtheories[i]->isComplete()) {
 452       return d_subtheories[i]->getModelValue(var);
 453     }
 454   }
 455   Unreachable();
 456 }
 457
 458 void TheoryBV::propagate(Effort e) {
 459   Debug("bitvector") << indent() << "TheoryBV::propagate()" << std::endl;
 460   if (options::bitblastMode() == theory::bv::BITBLAST_MODE_EAGER) {
 461     return;
 462   }
 463
 464   if (inConflict()) {
 465     return;
 466   }
 467
 468   // go through stored propagations
 469   bool ok = true;
 470   for (; d_literalsToPropagateIndex < d_literalsToPropagate.size() && ok; d_literalsToPropagateIndex = d_literalsToPropagateIndex + 1) {
 471     TNode literal = d_literalsToPropagate[d_literalsToPropagateIndex];
 472     // temporary fix for incremental bit-blasting
 473     if (d_valuation.isSatLiteral(literal)) {
 474       Debug("bitvector::propagate") << "TheoryBV:: propagating " << literal <<"\n";
 475       ok = d_out->propagate(literal);
 476     }
 477   }
 478
 479   if (!ok) {
 480     Debug("bitvector::propagate") << indent() << "TheoryBV::propagate(): conflict from theory engine" << std::endl;
 481     setConflict();
 482   }
 483 }
 484
 485
 486 Theory::PPAssertStatus TheoryBV::ppAssert(TNode in, SubstitutionMap& outSubstitutions) {
 487   switch(in.getKind()) {
 488   case kind::EQUAL:
 489     {
 490       if (in[0].isVar() && !in[1].hasSubterm(in[0])) {
 491         ++(d_statistics.d_solveSubstitutions);
 492         outSubstitutions.addSubstitution(in[0], in[1]);
 493         return PP_ASSERT_STATUS_SOLVED;
 494       }
 495       if (in[1].isVar() && !in[0].hasSubterm(in[1])) {
 496         ++(d_statistics.d_solveSubstitutions);
 497         outSubstitutions.addSubstitution(in[1], in[0]);
 498         return PP_ASSERT_STATUS_SOLVED;
 499       }
 500       Node node = Rewriter::rewrite(in);
 501       if ((node[0].getKind() == kind::BITVECTOR_EXTRACT && node[1].isConst()) ||
 502           (node[1].getKind() == kind::BITVECTOR_EXTRACT && node[0].isConst())) {
 503         Node extract = node[0].isConst() ? node[1] : node[0];
 504         if (extract[0].getKind() == kind::VARIABLE) {
 505           Node c = node[0].isConst() ? node[0] : node[1];
 506
 507           unsigned high = utils::getExtractHigh(extract);
 508           unsigned low = utils::getExtractLow(extract);
 509           unsigned var_bitwidth = utils::getSize(extract[0]);
 510           std::vector<Node> children;
 511
 512           if (low == 0) {
 513             Assert (high != var_bitwidth - 1);
 514             unsigned skolem_size = var_bitwidth - high - 1;
 515             Node skolem = utils::mkVar(skolem_size);
 516             children.push_back(skolem);
 517             children.push_back(c);
 518           } else if (high == var_bitwidth - 1) {
 519             unsigned skolem_size = low;
 520             Node skolem = utils::mkVar(skolem_size);
 521             children.push_back(c);
 522             children.push_back(skolem);
 523           } else {
 524             unsigned skolem1_size = low;
 525             unsigned skolem2_size = var_bitwidth - high - 1;
 526             Node skolem1 = utils::mkVar(skolem1_size);
 527             Node skolem2 = utils::mkVar(skolem2_size);
 528             children.push_back(skolem2);
 529             children.push_back(c);
 530             children.push_back(skolem1);
 531           }
 532           Node concat = utils::mkNode(kind::BITVECTOR_CONCAT, children);
 533           Assert (utils::getSize(concat) == utils::getSize(extract[0]));
 534           outSubstitutions.addSubstitution(extract[0], concat);
 535           return PP_ASSERT_STATUS_SOLVED;
 536         }
 537       }
 538     }
 539     break;
 540   case kind::BITVECTOR_ULT:
 541   case kind::BITVECTOR_SLT:
 542   case kind::BITVECTOR_ULE:
 543   case kind::BITVECTOR_SLE:
 544
 545   default:
 546     // TODO other predicates
 547     break;
 548   }
 549   return PP_ASSERT_STATUS_UNSOLVED;
 550 }
 551
 552 Node TheoryBV::ppRewrite(TNode t)
 553 {
 554   Debug("bv-pp-rewrite") << "TheoryBV::ppRewrite " << t << "\n";
 555   Node res = t;
 556   if (RewriteRule<BitwiseEq>::applies(t)) {
 557     Node result = RewriteRule<BitwiseEq>::run<false>(t);
 558     res = Rewriter::rewrite(result);
 559   } else if (d_isCoreTheory && t.getKind() == kind::EQUAL) {
 560     std::vector<Node> equalities;
 561     Slicer::splitEqualities(t, equalities);
 562     res = utils::mkAnd(equalities);
 563   } else if (RewriteRule<UltPlusOne>::applies(t)) {
 564     Node result = RewriteRule<UltPlusOne>::run<false>(t);
 565     res = Rewriter::rewrite(result);
 566   } else if( res.getKind() == kind::EQUAL &&
 567       ((res[0].getKind() == kind::BITVECTOR_PLUS &&
 568         RewriteRule<ConcatToMult>::applies(res[1])) ||
 569        res[1].getKind() == kind::BITVECTOR_PLUS &&
 570        RewriteRule<ConcatToMult>::applies(res[0]))) {
 571     Node mult = RewriteRule<ConcatToMult>::applies(res[0])?
 572       RewriteRule<ConcatToMult>::run<false>(res[0]) :
 573       RewriteRule<ConcatToMult>::run<true>(res[1]);
 574     Node factor = mult[0];
 575     Node sum =  RewriteRule<ConcatToMult>::applies(res[0])? res[1] : res[0];
 576     Node new_eq =utils::mkNode(kind::EQUAL, sum, mult);
 577     Node rewr_eq = RewriteRule<SolveEq>::run<true>(new_eq);
 578     if (rewr_eq[0].isVar() || rewr_eq[1].isVar()){
 579       res = Rewriter::rewrite(rewr_eq);
 580     } else {
 581       res = t;
 582     }
 583   }
 584
 585
 586   // if(t.getKind() == kind::EQUAL &&
 587   //    ((t[0].getKind() == kind::BITVECTOR_MULT && t[1].getKind() == kind::BITVECTOR_PLUS) ||
 588   //     (t[1].getKind() == kind::BITVECTOR_MULT && t[0].getKind() == kind::BITVECTOR_PLUS))) {
 589   //   // if we have an equality between a multiplication and addition
 590   //   // try to express multiplication in terms of addition
 591   //   Node mult = t[0].getKind() == kind::BITVECTOR_MULT? t[0] : t[1];
 592   //   Node add = t[0].getKind() == kind::BITVECTOR_PLUS? t[0] : t[1];
 593   //   if (RewriteRule<MultSlice>::applies(mult)) {
 594   //     Node new_mult = RewriteRule<MultSlice>::run<false>(mult);
 595   //     Node new_eq = Rewriter::rewrite(utils::mkNode(kind::EQUAL, new_mult, add));
 596
 597   //     // the simplification can cause the formula to blow up
 598   //     // only apply if formula reduced
 599   //     if (d_subtheoryMap.find(SUB_BITBLAST) != d_subtheoryMap.end()) {
 600   //       BitblastSolver* bv = (BitblastSolver*)d_subtheoryMap[SUB_BITBLAST];
 601   //       uint64_t old_size = bv->computeAtomWeight(t);
 602   //       Assert (old_size);
 603   //       uint64_t new_size = bv->computeAtomWeight(new_eq);
 604   //       double ratio = ((double)new_size)/old_size;
 605   //       if (ratio <= 0.4) {
 606   //         ++(d_statistics.d_numMultSlice);
 607   //         return new_eq;
 608   //       }
 609   //     }
 610
 611   //     if (new_eq.getKind() == kind::CONST_BOOLEAN) {
 612   //       ++(d_statistics.d_numMultSlice);
 613   //       return new_eq;
 614   //     }
 615   //   }
 616   // }
 617
 618   if (options::bvAbstraction() && t.getType().isBoolean()) {
 619     d_abstractionModule->addInputAtom(res);
 620   }
 621   Debug("bv-pp-rewrite") << "to   " << res << "\n";
 622   return res;
 623 }
 624
 625 void TheoryBV::presolve() {
 626   Debug("bitvector") << "TheoryBV::presolve" << endl;
 627 }
 628
 629 static int prop_count = 0;
 630
 631 bool TheoryBV::storePropagation(TNode literal, SubTheory subtheory)
 632 {
 633   Debug("bitvector::propagate") << indent() << getSatContext()->getLevel() << " " << "TheoryBV::storePropagation(" << literal << ", " << subtheory << ")" << std::endl;
 634   prop_count++;
 635
 636   // If already in conflict, no more propagation
 637   if (d_conflict) {
 638     Debug("bitvector::propagate") << indent() << "TheoryBV::storePropagation(" << literal << ", " << subtheory << "): already in conflict" << std::endl;
 639     return false;
 640   }
 641
 642   // If propagated already, just skip
 643   PropagatedMap::const_iterator find = d_propagatedBy.find(literal);
 644   if (find != d_propagatedBy.end()) {
 645     return true;
 646   } else {
 647     bool polarity = literal.getKind() != kind::NOT;
 648     Node negatedLiteral = polarity ? literal.notNode() : (Node) literal[0];
 649     find = d_propagatedBy.find(negatedLiteral);
 650     if (find != d_propagatedBy.end() && (*find).second != subtheory) {
 651       // Safe to ignore this one, subtheory should produce a conflict
 652       return true;
 653     }
 654
 655     d_propagatedBy[literal] = subtheory;
 656   }
 657
 658   // Propagate differs depending on the subtheory
 659   // * bitblaster needs to be left alone until it's done, otherwise it doesn't know how to explain
 660   // * equality engine can propagate eagerly
 661   bool ok = true;
 662   if (subtheory == SUB_CORE) {
 663     d_out->propagate(literal);
 664     if (!ok) {
 665       setConflict();
 666     }
 667   } else {
 668     d_literalsToPropagate.push_back(literal);
 669   }
 670   return ok;
 671
 672 }/* TheoryBV::propagate(TNode) */
 673
 674
 675 void TheoryBV::explain(TNode literal, std::vector<TNode>& assumptions) {
 676   Assert (wasPropagatedBySubtheory(literal));
 677   SubTheory sub = getPropagatingSubtheory(literal);
 678   d_subtheoryMap[sub]->explain(literal, assumptions);
 679 }
 680
 681
 682 Node TheoryBV::explain(TNode node) {
 683   Debug("bitvector::explain") << "TheoryBV::explain(" << node << ")" << std::endl;
 684   std::vector<TNode> assumptions;
 685
 686   // Ask for the explanation
 687   explain(node, assumptions);
 688   // this means that it is something true at level 0
 689   if (assumptions.size() == 0) {
 690     return utils::mkTrue();
 691   }
 692   // return the explanation
 693   Node explanation = utils::mkAnd(assumptions);
 694   Debug("bitvector::explain") << "TheoryBV::explain(" << node << ") => " << explanation << std::endl;
 695   return explanation;
 696 }
 697
 698
 699 void TheoryBV::addSharedTerm(TNode t) {
 700   Debug("bitvector::sharing") << indent() << "TheoryBV::addSharedTerm(" << t << ")" << std::endl;
 701   d_sharedTermsSet.insert(t);
 702   if (options::bitvectorEqualitySolver()) {
 703     for (unsigned i = 0; i < d_subtheories.size(); ++i) {
 704       d_subtheories[i]->addSharedTerm(t);
 705     }
 706   }
 707 }
 708
 709
 710 EqualityStatus TheoryBV::getEqualityStatus(TNode a, TNode b)
 711 {
 712   Assert (options::bitblastMode() == theory::bv::BITBLAST_MODE_LAZY);
 713   for (unsigned i = 0; i < d_subtheories.size(); ++i) {
 714     EqualityStatus status = d_subtheories[i]->getEqualityStatus(a, b);
 715     if (status != EQUALITY_UNKNOWN) {
 716       return status;
 717     }
 718   }
 719   return EQUALITY_UNKNOWN; ;
 720 }
 721
 722
 723 void TheoryBV::enableCoreTheorySlicer() {
 724   Assert (!d_calledPreregister);
 725   d_isCoreTheory = true;
 726   if (d_subtheoryMap.find(SUB_CORE) != d_subtheoryMap.end()) {
 727     CoreSolver* core = (CoreSolver*)d_subtheoryMap[SUB_CORE];
 728     core->enableSlicer();
 729   }
 730 }
 731
 732
 733 void TheoryBV::ppStaticLearn(TNode in, NodeBuilder<>& learned) {
 734   if(d_staticLearnCache.find(in) != d_staticLearnCache.end()){
 735     return;
 736   }
 737   d_staticLearnCache.insert(in);
 738
 739   if (in.getKind() == kind::EQUAL) {
 740     if(in[0].getKind() == kind::BITVECTOR_PLUS && in[1].getKind() == kind::BITVECTOR_SHL ||
 741        in[1].getKind() == kind::BITVECTOR_PLUS && in[0].getKind() == kind::BITVECTOR_SHL){
 742       TNode p = in[0].getKind() == kind::BITVECTOR_PLUS ? in[0] : in[1];
 743       TNode s = in[0].getKind() == kind::BITVECTOR_PLUS ? in[1] : in[0];
 744
 745       if(p.getNumChildren() == 2
 746          && p[0].getKind()  == kind::BITVECTOR_SHL
 747          && p[1].getKind()  == kind::BITVECTOR_SHL ){
 748         unsigned size = utils::getSize(s);
 749         Node one = utils::mkConst(size, 1u);
 750         if(s[0] == one && p[0][0] == one && p[1][0] == one){
 751           Node zero = utils::mkConst(size, 0u);
 752           TNode b = p[0];
 753           TNode c = p[1];
 754           // (s : 1 << S) = (b : 1 << B) + (c : 1 << C)
 755           Node b_eq_0 = b.eqNode(zero);
 756           Node c_eq_0 = c.eqNode(zero);
 757           Node b_eq_c = b.eqNode(c);
 758
 759           Node dis = utils::mkNode(kind::OR, b_eq_0, c_eq_0, b_eq_c);
 760           Node imp = in.impNode(dis);
 761           learned << imp;
 762         }
 763       }
 764     }
 765   }else if(in.getKind() == kind::AND){
 766     for(size_t i = 0, N = in.getNumChildren(); i < N; ++i){
 767       ppStaticLearn(in[i], learned);
 768     }
 769   }
 770 }
 771
 772 bool TheoryBV::applyAbstraction(const std::vector<Node>& assertions, std::vector<Node>& new_assertions) {
 773   bool changed = d_abstractionModule->applyAbstraction(assertions, new_assertions);
 774   if (changed &&
 775       options::bitblastMode() == theory::bv::BITBLAST_MODE_EAGER &&
 776       options::bitvectorAig()) {
 777     // disable AIG mode
 778     AlwaysAssert (!d_eagerSolver->isInitialized());
 779     d_eagerSolver->turnOffAig();
 780     d_eagerSolver->initialize();
 781   }
 782   return changed;
 783 }
 784
 785 void TheoryBV::setConflict(Node conflict) {
 786   if (options::bvAbstraction()) {
 787     Node new_conflict = d_abstractionModule->simplifyConflict(conflict);
 788
 789     std::vector<Node> lemmas;
 790     lemmas.push_back(new_conflict);
 791     d_abstractionModule->generalizeConflict(new_conflict, lemmas);
 792     for (unsigned i = 0; i < lemmas.size(); ++i) {
 793       lemma(utils::mkNode(kind::NOT, lemmas[i]));
 794     }
 795   }
 796   d_conflict = true;
 797   d_conflictNode = conflict;
 798 }