xref: /dports/math/stp/stp-2.3.3/lib/ToSat/AIG/ToCNFAIG.cpp

/********************************************************************
 * AUTHORS: Trevor Hansen
 *
 * BEGIN DATE: Feb, 2010
 *
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#include "stp/ToSat/AIG/ToCNFAIG.h"

namespace stp
{

// Can it only add in the new variables somehow??
void addVariables(BBNodeManagerAIG& mgr, Cnf_Dat_t*& cnfData,
                  ToSATBase::ASTNodeToSATVar& nodeToVars)
{
  BBNodeManagerAIG::SymbolToBBNode::const_iterator it;
  // Each symbol maps to a vector of CNF variables.
  for (it = mgr.symbolToBBNode.begin(); it != mgr.symbolToBBNode.end(); it++)
  {
    const ASTNode& n = it->first;
    const vector<BBNodeAIG>& b = it->second;

    const int width = (n.GetType() == BOOLEAN_TYPE) ? 1 : n.GetValueWidth();

    // INT_MAX for parts of symbols that didn't get encoded.
    vector<unsigned> v(width, ~((unsigned)0));

    for (unsigned i = 0; i < b.size(); i++)
    {
      if (!b[i].IsNull())
      {
        Aig_Obj_t* pObj;
        pObj = (Aig_Obj_t*)Vec_PtrEntry(mgr.aigMgr->vPis, b[i].symbol_index);
        v[i] = cnfData->pVarNums[pObj->Id];
      }
    }
    nodeToVars.insert(make_pair(n, v));
  }
}

void ToCNFAIG::dag_aware_aig_rewrite(const bool needAbsRef,
                                     BBNodeManagerAIG& mgr)
{
  const int nodeCount = mgr.aigMgr->nObjs[AIG_OBJ_AND];

  if (!needAbsRef && uf.enable_AIG_rewrites_flag)
  {
    Dar_LibStart();
    Dar_RwrPar_t Pars, *pPars = &Pars;
    Dar_ManDefaultRwrParams(pPars);

    // Assertion errors occur with this enabled.
    // pPars->fUseZeros = 1;

    // For mul63bit.smt2 with iterations =3 & nCutsMax = 8
    // CNF generation was taking 139 seconds, solving 10 seconds.

    // With nCutsMax =2, CNF generation takes 16 seconds, solving 10 seconds.
    // The rewriting doesn't remove as many nodes of course..
    const int iterations = 3;

    for (int i = 0; i < iterations; i++)
    {
      Aig_Man_t* pTemp;
      mgr.aigMgr = Aig_ManDup(pTemp = mgr.aigMgr, 0);
      Aig_ManStop(pTemp);
      Dar_ManRewrite(mgr.aigMgr, pPars);

      mgr.aigMgr = Aig_ManDup(pTemp = mgr.aigMgr, 0);
      Aig_ManStop(pTemp);

      if (uf.stats_flag)
        cerr << "After rewrite [" << i
             << "]  nodes:" << mgr.aigMgr->nObjs[AIG_OBJ_AND] << endl;

      //Fixedpoint reached?
      if (nodeCount == mgr.aigMgr->nObjs[AIG_OBJ_AND])
        break;
    }
  }
}

void ToCNFAIG::toCNF(const BBNodeAIG& top, Cnf_Dat_t*& cnfData,
                     ToSATBase::ASTNodeToSATVar& nodeToVars, bool needAbsRef,
                     BBNodeManagerAIG& mgr)
{
  assert(cnfData == NULL);

  Aig_ObjCreatePo(mgr.aigMgr, top.n);
  if (!needAbsRef)
  {
    Aig_ManCleanup(mgr.aigMgr); // remove nodes not connected to the PO.
  }
  assert(Aig_ManCheck(mgr.aigMgr)); // check that AIG looks ok.

  assert(Aig_ManPoNum(mgr.aigMgr) == 1);

  // UseZeroes gives assertion errors.
  // Rewriting is sometimes very slow. Can it be configured to be faster?
  // What about refactoring???

  if (uf.stats_flag)
  {
    cerr << "Nodes before AIG rewrite:" << mgr.aigMgr->nObjs[AIG_OBJ_AND]
         << endl;
  }

  dag_aware_aig_rewrite(needAbsRef, mgr);

  if (!uf.simple_cnf)
  {
    cnfData = Cnf_Derive(mgr.aigMgr, 0);
    if (uf.stats_flag)
      cerr << "advanced CNF" << endl;
  }
  else
  {
    cnfData = Cnf_DeriveSimple(mgr.aigMgr, 0);
    if (uf.stats_flag)
      cerr << "simple CNF" << endl;
  }
  assert(cnfData != NULL);

  fill_node_to_var(cnfData, nodeToVars, mgr);
}

void ToCNFAIG::fill_node_to_var(Cnf_Dat_t* cnfData,
                                ToSATBase::ASTNodeToSATVar& nodeToVars,
                                BBNodeManagerAIG& mgr)
{
  BBNodeManagerAIG::SymbolToBBNode::const_iterator it;
  assert(nodeToVars.size() == 0);

  // todo. cf. with addvariables above...
  // Each symbol maps to a vector of CNF variables.
  for (it = mgr.symbolToBBNode.begin(); it != mgr.symbolToBBNode.end(); it++)
  {
    const ASTNode& n = it->first;
    const vector<BBNodeAIG>& b = it->second;
    assert(nodeToVars.find(n) == nodeToVars.end());

    const int width = (n.GetType() == BOOLEAN_TYPE) ? 1 : n.GetValueWidth();

    // INT_MAX for parts of symbols that didn't get encoded.
    vector<unsigned> v(width, ~((unsigned)0));

    for (unsigned i = 0; i < b.size(); i++)
    {
      if (!b[i].IsNull())
      {
        Aig_Obj_t* pObj;
        pObj = (Aig_Obj_t*)Vec_PtrEntry(mgr.aigMgr->vPis, b[i].symbol_index);
        v[i] = cnfData->pVarNums[pObj->Id];
      }
    }

    nodeToVars.insert(make_pair(n, v));
  }
}
}