abc/src/opt/sbd/sbdWin.c - third_party/vtr-verilog-to-routing - Git at Google


            
            /**CFile****************************************************************


              FileName    [sbd.c]


              SystemName  [ABC: Logic synthesis and verification system.]


              PackageName [SAT-based optimization using internal don't-cares.]


              Synopsis    []


              Author      [Alan Mishchenko]


              Affiliation [UC Berkeley]


              Date        [Ver. 1.0. Started - June 20, 2005.]


              Revision    [$Id: sbd.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]


            ***********************************************************************/


            #include "sbdInt.h"


            ABC_NAMESPACE_IMPL_START


            ////////////////////////////////////////////////////////////////////////

            
            ///                        DECLARATIONS                              ///

            
            ////////////////////////////////////////////////////////////////////////


            ////////////////////////////////////////////////////////////////////////

            
            ///                     FUNCTION DEFINITIONS                         ///

            
            ////////////////////////////////////////////////////////////////////////


            /**Function*************************************************************


              Synopsis    [Constructs SAT solver for the window.]


              Description [The window for the pivot node (Pivot) is represented as

            
              a DFS ordered array of objects (vWinObjs) whose indexed in the array

            
              (which will be used as SAT variables) are given in array vObj2Var.

            
              The TFO nodes are listed as the last ones in vWinObjs. The root nodes

            
              are labeled with Abc_LitIsCompl() in vTfo and also given in vRoots.

            
              If fQbf is 1, returns the instance meant for QBF solving. It is using

            
              the last variable (LastVar) as the placeholder for the second copy

            
              of the pivot node.]


              SideEffects []


              SeeAlso     []


            ***********************************************************************/

            
            sat_solver * Sbd_ManSatSolver( sat_solver * pSat, Gia_Man_t * p, Vec_Int_t * vMirrors,

            
                                           int Pivot, Vec_Int_t * vWinObjs, Vec_Int_t * vObj2Var,

            
                                           Vec_Int_t * vTfo, Vec_Int_t * vRoots, int fQbf )

            
            {

            
                Gia_Obj_t * pObj;

            
                int i, iLit = 1, iObj, Fan0, Fan1, Lit0m, Lit1m, Node, fCompl0, fCompl1, RetValue;

            
                int TfoStart = Vec_IntSize(vWinObjs) - Vec_IntSize(vTfo);

            
                int PivotVar = Vec_IntEntry(vObj2Var, Pivot);

            
                int LastVar = Vec_IntSize(vWinObjs) + Vec_IntSize(vTfo) + Vec_IntSize(vRoots);

            
                //Vec_IntPrint( vWinObjs );

            
                //Vec_IntPrint( vTfo );

            
                //Vec_IntPrint( vRoots );

            
                // create SAT solver

            
                if ( pSat == NULL )

            
                    pSat = sat_solver_new();

            
                else

            
                    sat_solver_restart( pSat );

            
                sat_solver_setnvars( pSat, Vec_IntSize(vWinObjs) + Vec_IntSize(vTfo) + Vec_IntSize(vRoots) + SBD_FVAR_MAX );

            
                // create constant 0 clause

            
                sat_solver_addclause( pSat, &iLit, &iLit + 1 );

            
                // add clauses for all nodes

            
                Vec_IntForEachEntryStart( vWinObjs, iObj, i, 1 )

            
                {

            
                    pObj = Gia_ManObj( p, iObj );

            
                    if ( Gia_ObjIsCi(pObj) )

            
                        continue;

            
                    assert( Gia_ObjIsAnd(pObj) );

            
                    assert( Vec_IntEntry( vMirrors, iObj ) < 0 );

            
                    Node = Vec_IntEntry( vObj2Var, iObj );

            
                    Lit0m = Vec_IntEntry( vMirrors, Gia_ObjFaninId0(pObj, iObj) );

            
                    Lit1m = Vec_IntEntry( vMirrors, Gia_ObjFaninId1(pObj, iObj) );

            
                    Fan0 = Lit0m >= 0 ? Abc_Lit2Var(Lit0m) : Gia_ObjFaninId0(pObj, iObj);

            
                    Fan1 = Lit1m >= 0 ? Abc_Lit2Var(Lit1m) : Gia_ObjFaninId1(pObj, iObj);

            
                    Fan0 = Vec_IntEntry( vObj2Var, Fan0 );

            
                    Fan1 = Vec_IntEntry( vObj2Var, Fan1 );

            
                    fCompl0 = Gia_ObjFaninC0(pObj) ^ (Lit0m >= 0 && Abc_LitIsCompl(Lit0m));

            
                    fCompl1 = Gia_ObjFaninC1(pObj) ^ (Lit1m >= 0 && Abc_LitIsCompl(Lit1m));

            
                    if ( Gia_ObjIsXor(pObj) )

            
                        sat_solver_add_xor( pSat, Node, Fan0, Fan1, fCompl0 ^ fCompl1 );

            
                    else

            
                        sat_solver_add_and( pSat, Node, Fan0, Fan1, fCompl0, fCompl1, 0 );

            
                }

            
                // add second clauses for the TFO

            
                Vec_IntForEachEntryStart( vWinObjs, iObj, i, TfoStart )

            
                {

            
                    pObj = Gia_ManObj( p, iObj );

            
                    assert( Gia_ObjIsAnd(pObj) );

            
                    assert( Vec_IntEntry( vMirrors, iObj ) < 0 );

            
                    Node = Vec_IntEntry( vObj2Var, iObj ) + Vec_IntSize(vTfo);

            
                    Lit0m = Vec_IntEntry( vMirrors, Gia_ObjFaninId0(pObj, iObj) );

            
                    Lit1m = Vec_IntEntry( vMirrors, Gia_ObjFaninId1(pObj, iObj) );

            
                    Fan0 = Lit0m >= 0 ? Abc_Lit2Var(Lit0m) : Gia_ObjFaninId0(pObj, iObj);

            
                    Fan1 = Lit1m >= 0 ? Abc_Lit2Var(Lit1m) : Gia_ObjFaninId1(pObj, iObj);

            
                    Fan0 = Vec_IntEntry( vObj2Var, Fan0 );

            
                    Fan1 = Vec_IntEntry( vObj2Var, Fan1 );

            
                    Fan0 = Fan0 < TfoStart ? Fan0 : Fan0 + Vec_IntSize(vTfo);

            
                    Fan1 = Fan1 < TfoStart ? Fan1 : Fan1 + Vec_IntSize(vTfo);

            
                    if ( fQbf )

            
                    {

            
                        Fan0 = Fan0 == PivotVar ? LastVar : Fan0;

            
                        Fan1 = Fan1 == PivotVar ? LastVar : Fan1;

            
                    }

            
                    fCompl0 = Gia_ObjFaninC0(pObj) ^ (!fQbf && Fan0 == PivotVar) ^ (Lit0m >= 0 && Abc_LitIsCompl(Lit0m));

            
                    fCompl1 = Gia_ObjFaninC1(pObj) ^ (!fQbf && Fan1 == PivotVar) ^ (Lit1m >= 0 && Abc_LitIsCompl(Lit1m));

            
                    if ( Gia_ObjIsXor(pObj) )

            
                        sat_solver_add_xor( pSat, Node, Fan0, Fan1, fCompl0 ^ fCompl1 );

            
                    else

            
                        sat_solver_add_and( pSat, Node, Fan0, Fan1, fCompl0, fCompl1, 0 );

            
                }

            
                if ( Vec_IntSize(vRoots) > 0 )

            
                {

            
                    // create XOR clauses for the roots

            
                    int nVars = Vec_IntSize(vWinObjs) + Vec_IntSize(vTfo);

            
                    Vec_Int_t * vFaninVars = Vec_IntAlloc( Vec_IntSize(vRoots) );

            
                    Vec_IntForEachEntry( vRoots, iObj, i )

            
                    {

            
                        assert( Vec_IntEntry( vMirrors, iObj ) < 0 );

            
                        Node = Vec_IntEntry( vObj2Var, iObj );

            
                        Vec_IntPush( vFaninVars, Abc_Var2Lit(nVars, 0) );

            
                        sat_solver_add_xor( pSat, Node, Node + Vec_IntSize(vTfo), nVars++, 0 );

            
                    }

            
                    // make OR clause for the last nRoots variables

            
                    RetValue = sat_solver_addclause( pSat, Vec_IntArray(vFaninVars), Vec_IntLimit(vFaninVars) );

            
                    Vec_IntFree( vFaninVars );

            
                    if ( RetValue == 0 )

            
                    {

            
                        sat_solver_delete( pSat );

            
                        return NULL;

            
                    }

            
                    assert( sat_solver_nvars(pSat) == nVars + SBD_FVAR_MAX );

            
                }

            
                else if ( fQbf )

            
                {

            
                    int n, pLits[2];

            
                    for ( n = 0; n < 2; n++ )

            
                    {

            
                        pLits[0] = Abc_Var2Lit( PivotVar, n );

            
                        pLits[1] = Abc_Var2Lit( LastVar, n );

            
                        RetValue = sat_solver_addclause( pSat, pLits, pLits + 2 );

            
                        assert( RetValue );

            
                    }

            
                }

            
                // finalize

            
                RetValue = sat_solver_simplify( pSat );

            
                if ( RetValue == 0 )

            
                {

            
                    sat_solver_delete( pSat );

            
                    return NULL;

            
                }

            
                return pSat;

            
            }


            /**Function*************************************************************


              Synopsis    [Solves one SAT problem.]


              Description [Computes node function for PivotVar with fanins in vDivSet

            
              using don't-care represented in the SAT solver. Uses array vValues to

            
              return the values of the first Vec_IntSize(vValues) SAT variables in case

            
              the implementation of the node with the given fanins does not exist.]


              SideEffects []


              SeeAlso     []


            ***********************************************************************/

            
            word Sbd_ManSolve( sat_solver * pSat, int PivotVar, int FreeVar, Vec_Int_t * vDivSet, Vec_Int_t * vDivVars, Vec_Int_t * vDivValues, Vec_Int_t * vTemp )

            
            {

            
                int nBTLimit = 0;

            
                word uCube, uTruth = 0;

            
                int status, i, iVar, nFinal, * pFinal, pLits[2], nIter = 0;

            
                assert( FreeVar < sat_solver_nvars(pSat) );

            
                assert( Vec_IntSize(vDivVars) == Vec_IntSize(vDivValues) );

            
                pLits[0] = Abc_Var2Lit( PivotVar, 0 ); // F = 1

            
                pLits[1] = Abc_Var2Lit( FreeVar, 0 );  // iNewLit

            
                while ( 1 )

            
                {

            
                    // find onset minterm

            
                    status = sat_solver_solve( pSat, pLits, pLits + 2, nBTLimit, 0, 0, 0 );

            
                    if ( status == l_Undef )

            
                        return SBD_SAT_UNDEC;

            
                    if ( status == l_False )

            
                        return uTruth;

            
                    assert( status == l_True );

            
                    // remember variable values

            
                    Vec_IntForEachEntry( vDivVars, iVar, i )

            
                        Vec_IntWriteEntry( vDivValues, i, 2*sat_solver_var_value(pSat, iVar) );

            
                    // collect divisor literals

            
                    Vec_IntClear( vTemp );

            
                    Vec_IntPush( vTemp, Abc_LitNot(pLits[0]) ); // F = 0

            
                    Vec_IntForEachEntry( vDivSet, iVar, i )

            
                        Vec_IntPush( vTemp, sat_solver_var_literal(pSat, iVar) );

            
                    // check against offset

            
                    status = sat_solver_solve( pSat, Vec_IntArray(vTemp), Vec_IntArray(vTemp) + Vec_IntSize(vTemp), nBTLimit, 0, 0, 0 );

            
                    if ( status == l_Undef )

            
                        return SBD_SAT_UNDEC;

            
                    if ( status == l_True )

            
                        break;

            
                    assert( status == l_False );

            
                    // compute cube and add clause

            
                    nFinal = sat_solver_final( pSat, &pFinal );

            
                    uCube = ~(word)0;

            
                    Vec_IntClear( vTemp );

            
                    Vec_IntPush( vTemp, Abc_LitNot(pLits[1]) ); // NOT(iNewLit)

            
                    for ( i = 0; i < nFinal; i++ )

            
                    {

            
                        if ( pFinal[i] == pLits[0] )

            
                            continue;

            
                        Vec_IntPush( vTemp, pFinal[i] );

            
                        iVar = Vec_IntFind( vDivSet, Abc_Lit2Var(pFinal[i]) );   assert( iVar >= 0 );

            
                        uCube &= Abc_LitIsCompl(pFinal[i]) ? s_Truths6[iVar] : ~s_Truths6[iVar];

            
                    }

            
                    uTruth |= uCube;

            
                    status = sat_solver_addclause( pSat, Vec_IntArray(vTemp), Vec_IntArray(vTemp) + Vec_IntSize(vTemp) );

            
                    assert( status );

            
                    nIter++;

            
                }

            
                assert( status == l_True );

            
                // store the counter-example

            
                Vec_IntForEachEntry( vDivVars, iVar, i )

            
                    Vec_IntAddToEntry( vDivValues, i, sat_solver_var_value(pSat, iVar) );


                for ( i = 0; i < Vec_IntSize(vDivValues); i++ )

            
                    Vec_IntAddToEntry( vDivValues, i, 0xC );

            
            /*

            
                // reduce the counter example

            
                for ( n = 0; n < 2; n++ )

            
                {

            
                    Vec_IntClear( vTemp );

            
                    Vec_IntPush( vTemp, Abc_Var2Lit(PivotVar, n) ); // n = 0 => F = 1  (expanding offset against onset)

            
                    for ( i = 0; i < Vec_IntSize(vValues); i++ )

            
                        Vec_IntPush( vTemp, Abc_Var2Lit(i, !((Vec_IntEntry(vValues, i) >> n) & 1)) );

            
                    status = sat_solver_solve( pSat, Vec_IntArray(vTemp), Vec_IntArray(vTemp) + Vec_IntSize(vTemp), nBTLimit, 0, 0, 0 );

            
                    assert( status == l_False );

            
                    // compute cube and add clause

            
                    nFinal = sat_solver_final( pSat, &pFinal );

            
                    for ( i = 0; i < nFinal; i++ )

            
                        if ( Abc_Lit2Var(pFinal[i]) != PivotVar )

            
                            Vec_IntAddToEntry( vValues, Abc_Lit2Var(pFinal[i]), 1 << (n+2) );

            
                }

            
            */

            
                return SBD_SAT_SAT;

            
            }


            /**Function*************************************************************


              Synopsis    []


              Description []


              SideEffects []


              SeeAlso     []


            ***********************************************************************/

            
            int Sbd_ManSolve2( sat_solver * pSat, int PivotVar, int FreeVar, Vec_Int_t * vDivVars, Vec_Int_t * vDivValues, Vec_Int_t * vTemp, Vec_Int_t * vSop )

            
            {

            
                int nBTLimit = 0;

            
                int status, i, iVar, nFinal, * pFinal, pLits[2], nIter = 0;

            
                assert( FreeVar < sat_solver_nvars(pSat) );

            
                assert( Vec_IntSize(vDivVars) == Vec_IntSize(vDivValues) );

            
                pLits[0] = Abc_Var2Lit( PivotVar, 0 ); // F = 1

            
                pLits[1] = Abc_Var2Lit( FreeVar, 0 );  // iNewLit

            
                Vec_IntClear( vSop );

            
                while ( 1 )

            
                {

            
                    // find onset minterm

            
                    status = sat_solver_solve( pSat, pLits, pLits + 2, nBTLimit, 0, 0, 0 );

            
                    if ( status == l_Undef )

            
                        return 0;

            
                    if ( status == l_False )

            
                        return 1;

            
                    assert( status == l_True );

            
                    // remember variable values

            
                    //for ( i = 0; i < Vec_IntSize(vValues); i++ )

            
                    //    Vec_IntWriteEntry( vValues, i, 2*sat_solver_var_value(pSat, i) );

            
                    // collect divisor literals

            
                    Vec_IntClear( vTemp );

            
                    Vec_IntPush( vTemp, Abc_LitNot(pLits[0]) ); // F = 0

            
                    //Vec_IntForEachEntry( vDivSet, iVar, i )

            
                    Vec_IntForEachEntry( vDivVars, iVar, i )

            
                        Vec_IntPush( vTemp, sat_solver_var_literal(pSat, iVar) );

            
                    // check against offset

            
                    status = sat_solver_solve( pSat, Vec_IntArray(vTemp), Vec_IntArray(vTemp) + Vec_IntSize(vTemp), nBTLimit, 0, 0, 0 );

            
                    if ( status == l_Undef )

            
                        return 0;

            
                    if ( status == l_True )

            
                        break;

            
                    assert( status == l_False );

            
                    // compute cube and add clause

            
                    nFinal = sat_solver_final( pSat, &pFinal );

            
                    Vec_IntClear( vTemp );

            
                    Vec_IntPush( vTemp, Abc_LitNot(pLits[1]) ); // NOT(iNewLit)

            
                    for ( i = 0; i < nFinal; i++ )

            
                    {

            
                        if ( pFinal[i] == pLits[0] )

            
                            continue;

            
                        Vec_IntPush( vTemp, pFinal[i] );

            
                        iVar = Vec_IntFind( vDivVars, Abc_Lit2Var(pFinal[i]) );   assert( iVar >= 0 );

            
                        //uCube &= Abc_LitIsCompl(pFinal[i]) ? s_Truths6[iVar] : ~s_Truths6[iVar];

            
                        Vec_IntPush( vSop, Abc_Var2Lit( iVar, !Abc_LitIsCompl(pFinal[i]) ) );

            
                    }

            
                    //uTruth |= uCube;

            
                    Vec_IntPush( vSop, -1 );

            
                    status = sat_solver_addclause( pSat, Vec_IntArray(vTemp), Vec_IntArray(vTemp) + Vec_IntSize(vTemp) );

            
                    assert( status );

            
                    nIter++;

            
                }

            
                assert( status == l_True );

            
                // store the counter-example

            
                //for ( i = 0; i < Vec_IntSize(vValues); i++ )

            
                //    Vec_IntAddToEntry( vValues, i, sat_solver_var_value(pSat, i) );

            
                return 0;

            
            }


            word Sbd_ManSolverSupp( Vec_Int_t * vSop, int * pInds, int * pnVars )

            
            {

            
                word Supp = 0;

            
                int i, Entry, nVars = 0;

            
                Vec_IntForEachEntry( vSop, Entry, i )

            
                {

            
                    if ( Entry == -1 )

            
                        continue;

            
                    assert( Abc_Lit2Var(Entry) < 64 );

            
                    if ( (Supp >> Abc_Lit2Var(Entry)) & 1 )

            
                        continue;

            
                    pInds[Abc_Lit2Var(Entry)] = nVars++;

            
                    Supp |= (word)1 << Abc_Lit2Var(Entry);

            
                }

            
                *pnVars = nVars;

            
                return Supp;

            
            }

            
            void Sbd_ManSolverPrint( Vec_Int_t * vSop )

            
            {

            
                int v, i, Entry, nVars, pInds[64];

            
                word Supp = Sbd_ManSolverSupp( vSop, pInds, &nVars );

            
                char Cube[65] = {'\0'};

            
                assert( Cube[nVars] == '\0' );

            
                for ( v = 0; v < nVars; v++ )

            
                    Cube[v] = '-';

            
                Vec_IntForEachEntry( vSop, Entry, i )

            
                {

            
                    if ( Entry == -1 )

            
                    {

            
                        printf( "%s\n", Cube );

            
                        for ( v = 0; v < nVars; v++ )

            
                            Cube[v] = '-';

            
                        continue;

            
                    }

            
                    Cube[pInds[Abc_Lit2Var(Entry)]] = '1' - (char)Abc_LitIsCompl(Entry);

            
                }

            
                Supp = 0;

            
            }

            
            void Sbd_ManSolveSelect( Gia_Man_t * p, Vec_Int_t * vMirrors, int Pivot, Vec_Int_t * vDivVars, Vec_Int_t * vDivValues, Vec_Int_t * vWinObjs, Vec_Int_t * vObj2Var, Vec_Int_t * vTfo, Vec_Int_t * vRoots )

            
            {

            
                Vec_Int_t * vSop = Vec_IntAlloc( 100 );

            
                Vec_Int_t * vTemp = Vec_IntAlloc( 100 );

            
                sat_solver * pSat = Sbd_ManSatSolver( NULL, p, vMirrors, Pivot, vWinObjs, vObj2Var, vTfo, vRoots, 0 );

            
                int PivotVar = Vec_IntEntry(vObj2Var, Pivot);

            
                int FreeVar = Vec_IntSize(vWinObjs) + Vec_IntSize(vTfo) + Vec_IntSize(vRoots);

            
                int Status = Sbd_ManSolve2( pSat, PivotVar, FreeVar, vDivVars, vDivValues, vTemp, vSop );

            
                printf( "Pivot = %4d. Divs = %4d.  ", Pivot, Vec_IntSize(vDivVars) );

            
                if ( Status == 0 )

            
                    printf( "UNSAT.\n" );

            
                else

            
                {

            
                    int nVars, pInds[64];

            
                    word Supp = Sbd_ManSolverSupp( vSop, pInds, &nVars );

            
                    //Sbd_ManSolverPrint( vSop );

            
                    printf( "SAT with %d vars and %d cubes.\n", nVars, Vec_IntCountEntry(vSop, -1) );

            
                    Supp = 0;

            
                }

            
                Vec_IntFree( vTemp );

            
                Vec_IntFree( vSop );

            
                sat_solver_delete( pSat );

            
            }


            /**Function*************************************************************


              Synopsis    [Returns a bunch of positive/negative random care minterms.]


              Description [Returns 0/1 if the functions is const 0/1.]


              SideEffects []


              SeeAlso     []


            ***********************************************************************/

            
            static void sat_solver_random_polarity(sat_solver* s)

            
            {

            
                int i, k;

            
                for ( i = 0; i < s->size; i += 64 )

            
                {

            
                    word Polar = Gia_ManRandomW(0);

            
                    for ( k = 0; k < 64 && (i << 6) + k < s->size; k++ )

            
                        s->polarity[(i << 6) + k] = Abc_TtGetBit(&Polar, k);

            
                }

            
            }

            
            int Sbd_ManCollectConstants( sat_solver * pSat, int nCareMints[2], int PivotVar, word * pVarSims[], Vec_Int_t * vInds )

            
            {

            
                int nBTLimit = 0;

            
                int i, Ind;

            
                assert( Vec_IntSize(vInds) == nCareMints[0] + nCareMints[1] );

            
                Vec_IntForEachEntry( vInds, Ind, i )

            
                {

            
                    int fOffSet = (int)(i < nCareMints[0]);

            
                    int status, k, iLit = Abc_Var2Lit( PivotVar, fOffSet );

            
                    sat_solver_random_polarity( pSat );

            
                    status = sat_solver_solve( pSat, &iLit, &iLit + 1, nBTLimit, 0, 0, 0 );

            
                    if ( status == l_Undef )

            
                        return -2;

            
                    if ( status == l_False )

            
                        return fOffSet;

            
                    for ( k = 0; k <= PivotVar; k++ )

            
                        if ( Abc_TtGetBit(pVarSims[k], Ind) != sat_solver_var_value(pSat, k) )

            
                            Abc_TtXorBit(pVarSims[k], Ind);

            
                }

            
                return -1;

            
            }


            int Sbd_ManCollectConstantsNew( sat_solver * pSat, Vec_Int_t * vDivVars, int nConsts, int PivotVar, word * pOnset, word * pOffset )

            
            {

            
                int nBTLimit = 0;

            
                int n, i, k, status, iLit, iVar;

            
                word * pPats[2] = {pOnset, pOffset};

            
                assert( Vec_IntSize(vDivVars) < 64 );

            
                for ( n = 0; n < 2; n++ )

            
                for ( i = 0; i < nConsts; i++ )

            
                {

            
                    sat_solver_random_polarity( pSat );

            
                    iLit = Abc_Var2Lit( PivotVar, n );

            
                    status = sat_solver_solve( pSat, &iLit, &iLit + 1, nBTLimit, 0, 0, 0 );

            
                    if ( status == l_Undef )

            
                        return -2;

            
                    if ( status == l_False )

            
                        return n;

            
                    pPats[n][i] = ((word)!n) << Vec_IntSize(vDivVars);

            
                    Vec_IntForEachEntry( vDivVars, iVar, k )

            
                        if ( sat_solver_var_value(pSat, iVar) )

            
                            Abc_TtXorBit(&pPats[n][i], k);

            
                }

            
                return -1;

            
            }


            ////////////////////////////////////////////////////////////////////////

            
            ///                       END OF FILE                                ///

            
            ////////////////////////////////////////////////////////////////////////


            ABC_NAMESPACE_IMPL_END
	/CFile**************************************************************

	FileName [sbd.c]

	SystemName [ABC: Logic synthesis and verification system.]

	PackageName [SAT-based optimization using internal don't-cares.]

	Synopsis []

	Author [Alan Mishchenko]

	Affiliation [UC Berkeley]

	Date [Ver. 1.0. Started - June 20, 2005.]

	Revision [$Id: sbd.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]

	***********************************************************************/

	#include "sbdInt.h"

	ABC_NAMESPACE_IMPL_START


	////////////////////////////////////////////////////////////////////////
	/// DECLARATIONS ///
	////////////////////////////////////////////////////////////////////////

	////////////////////////////////////////////////////////////////////////
	/// FUNCTION DEFINITIONS ///
	////////////////////////////////////////////////////////////////////////

	/Function***********************************************************

	Synopsis [Constructs SAT solver for the window.]

	Description [The window for the pivot node (Pivot) is represented as
	a DFS ordered array of objects (vWinObjs) whose indexed in the array
	(which will be used as SAT variables) are given in array vObj2Var.
	The TFO nodes are listed as the last ones in vWinObjs. The root nodes
	are labeled with Abc_LitIsCompl() in vTfo and also given in vRoots.
	If fQbf is 1, returns the instance meant for QBF solving. It is using
	the last variable (LastVar) as the placeholder for the second copy
	of the pivot node.]

	SideEffects []

	SeeAlso []

	***********************************************************************/
	sat_solver * Sbd_ManSatSolver( sat_solver * pSat, Gia_Man_t * p, Vec_Int_t * vMirrors,
	int Pivot, Vec_Int_t * vWinObjs, Vec_Int_t * vObj2Var,
	Vec_Int_t * vTfo, Vec_Int_t * vRoots, int fQbf )
	{
	Gia_Obj_t * pObj;
	int i, iLit = 1, iObj, Fan0, Fan1, Lit0m, Lit1m, Node, fCompl0, fCompl1, RetValue;
	int TfoStart = Vec_IntSize(vWinObjs) - Vec_IntSize(vTfo);
	int PivotVar = Vec_IntEntry(vObj2Var, Pivot);
	int LastVar = Vec_IntSize(vWinObjs) + Vec_IntSize(vTfo) + Vec_IntSize(vRoots);
	//Vec_IntPrint( vWinObjs );
	//Vec_IntPrint( vTfo );
	//Vec_IntPrint( vRoots );
	// create SAT solver
	if ( pSat == NULL )
	pSat = sat_solver_new();
	else
	sat_solver_restart( pSat );
	sat_solver_setnvars( pSat, Vec_IntSize(vWinObjs) + Vec_IntSize(vTfo) + Vec_IntSize(vRoots) + SBD_FVAR_MAX );
	// create constant 0 clause
	sat_solver_addclause( pSat, &iLit, &iLit + 1 );
	// add clauses for all nodes
	Vec_IntForEachEntryStart( vWinObjs, iObj, i, 1 )
	{
	pObj = Gia_ManObj( p, iObj );
	if ( Gia_ObjIsCi(pObj) )
	continue;
	assert( Gia_ObjIsAnd(pObj) );
	assert( Vec_IntEntry( vMirrors, iObj ) < 0 );
	Node = Vec_IntEntry( vObj2Var, iObj );
	Lit0m = Vec_IntEntry( vMirrors, Gia_ObjFaninId0(pObj, iObj) );
	Lit1m = Vec_IntEntry( vMirrors, Gia_ObjFaninId1(pObj, iObj) );
	Fan0 = Lit0m >= 0 ? Abc_Lit2Var(Lit0m) : Gia_ObjFaninId0(pObj, iObj);
	Fan1 = Lit1m >= 0 ? Abc_Lit2Var(Lit1m) : Gia_ObjFaninId1(pObj, iObj);
	Fan0 = Vec_IntEntry( vObj2Var, Fan0 );
	Fan1 = Vec_IntEntry( vObj2Var, Fan1 );
	fCompl0 = Gia_ObjFaninC0(pObj) ^ (Lit0m >= 0 && Abc_LitIsCompl(Lit0m));
	fCompl1 = Gia_ObjFaninC1(pObj) ^ (Lit1m >= 0 && Abc_LitIsCompl(Lit1m));
	if ( Gia_ObjIsXor(pObj) )
	sat_solver_add_xor( pSat, Node, Fan0, Fan1, fCompl0 ^ fCompl1 );
	else
	sat_solver_add_and( pSat, Node, Fan0, Fan1, fCompl0, fCompl1, 0 );
	}
	// add second clauses for the TFO
	Vec_IntForEachEntryStart( vWinObjs, iObj, i, TfoStart )
	{
	pObj = Gia_ManObj( p, iObj );
	assert( Gia_ObjIsAnd(pObj) );
	assert( Vec_IntEntry( vMirrors, iObj ) < 0 );
	Node = Vec_IntEntry( vObj2Var, iObj ) + Vec_IntSize(vTfo);
	Lit0m = Vec_IntEntry( vMirrors, Gia_ObjFaninId0(pObj, iObj) );
	Lit1m = Vec_IntEntry( vMirrors, Gia_ObjFaninId1(pObj, iObj) );
	Fan0 = Lit0m >= 0 ? Abc_Lit2Var(Lit0m) : Gia_ObjFaninId0(pObj, iObj);
	Fan1 = Lit1m >= 0 ? Abc_Lit2Var(Lit1m) : Gia_ObjFaninId1(pObj, iObj);
	Fan0 = Vec_IntEntry( vObj2Var, Fan0 );
	Fan1 = Vec_IntEntry( vObj2Var, Fan1 );
	Fan0 = Fan0 < TfoStart ? Fan0 : Fan0 + Vec_IntSize(vTfo);
	Fan1 = Fan1 < TfoStart ? Fan1 : Fan1 + Vec_IntSize(vTfo);
	if ( fQbf )
	{
	Fan0 = Fan0 == PivotVar ? LastVar : Fan0;
	Fan1 = Fan1 == PivotVar ? LastVar : Fan1;
	}
	fCompl0 = Gia_ObjFaninC0(pObj) ^ (!fQbf && Fan0 == PivotVar) ^ (Lit0m >= 0 && Abc_LitIsCompl(Lit0m));
	fCompl1 = Gia_ObjFaninC1(pObj) ^ (!fQbf && Fan1 == PivotVar) ^ (Lit1m >= 0 && Abc_LitIsCompl(Lit1m));
	if ( Gia_ObjIsXor(pObj) )
	sat_solver_add_xor( pSat, Node, Fan0, Fan1, fCompl0 ^ fCompl1 );
	else
	sat_solver_add_and( pSat, Node, Fan0, Fan1, fCompl0, fCompl1, 0 );
	}
	if ( Vec_IntSize(vRoots) > 0 )
	{
	// create XOR clauses for the roots
	int nVars = Vec_IntSize(vWinObjs) + Vec_IntSize(vTfo);
	Vec_Int_t * vFaninVars = Vec_IntAlloc( Vec_IntSize(vRoots) );
	Vec_IntForEachEntry( vRoots, iObj, i )
	{
	assert( Vec_IntEntry( vMirrors, iObj ) < 0 );
	Node = Vec_IntEntry( vObj2Var, iObj );
	Vec_IntPush( vFaninVars, Abc_Var2Lit(nVars, 0) );
	sat_solver_add_xor( pSat, Node, Node + Vec_IntSize(vTfo), nVars++, 0 );
	}
	// make OR clause for the last nRoots variables
	RetValue = sat_solver_addclause( pSat, Vec_IntArray(vFaninVars), Vec_IntLimit(vFaninVars) );
	Vec_IntFree( vFaninVars );
	if ( RetValue == 0 )
	{
	sat_solver_delete( pSat );
	return NULL;
	}
	assert( sat_solver_nvars(pSat) == nVars + SBD_FVAR_MAX );
	}
	else if ( fQbf )
	{
	int n, pLits[2];
	for ( n = 0; n < 2; n++ )
	{
	pLits[0] = Abc_Var2Lit( PivotVar, n );
	pLits[1] = Abc_Var2Lit( LastVar, n );
	RetValue = sat_solver_addclause( pSat, pLits, pLits + 2 );
	assert( RetValue );
	}
	}
	// finalize
	RetValue = sat_solver_simplify( pSat );
	if ( RetValue == 0 )
	{
	sat_solver_delete( pSat );
	return NULL;
	}
	return pSat;
	}

	/Function***********************************************************

	Synopsis [Solves one SAT problem.]

	Description [Computes node function for PivotVar with fanins in vDivSet
	using don't-care represented in the SAT solver. Uses array vValues to
	return the values of the first Vec_IntSize(vValues) SAT variables in case
	the implementation of the node with the given fanins does not exist.]

	SideEffects []

	SeeAlso []

	***********************************************************************/
	word Sbd_ManSolve( sat_solver * pSat, int PivotVar, int FreeVar, Vec_Int_t * vDivSet, Vec_Int_t * vDivVars, Vec_Int_t * vDivValues, Vec_Int_t * vTemp )
	{
	int nBTLimit = 0;
	word uCube, uTruth = 0;
	int status, i, iVar, nFinal, * pFinal, pLits[2], nIter = 0;
	assert( FreeVar < sat_solver_nvars(pSat) );
	assert( Vec_IntSize(vDivVars) == Vec_IntSize(vDivValues) );
	pLits[0] = Abc_Var2Lit( PivotVar, 0 ); // F = 1
	pLits[1] = Abc_Var2Lit( FreeVar, 0 ); // iNewLit
	while ( 1 )
	{
	// find onset minterm
	status = sat_solver_solve( pSat, pLits, pLits + 2, nBTLimit, 0, 0, 0 );
	if ( status == l_Undef )
	return SBD_SAT_UNDEC;
	if ( status == l_False )
	return uTruth;
	assert( status == l_True );
	// remember variable values
	Vec_IntForEachEntry( vDivVars, iVar, i )
	Vec_IntWriteEntry( vDivValues, i, 2*sat_solver_var_value(pSat, iVar) );
	// collect divisor literals
	Vec_IntClear( vTemp );
	Vec_IntPush( vTemp, Abc_LitNot(pLits[0]) ); // F = 0
	Vec_IntForEachEntry( vDivSet, iVar, i )
	Vec_IntPush( vTemp, sat_solver_var_literal(pSat, iVar) );
	// check against offset
	status = sat_solver_solve( pSat, Vec_IntArray(vTemp), Vec_IntArray(vTemp) + Vec_IntSize(vTemp), nBTLimit, 0, 0, 0 );
	if ( status == l_Undef )
	return SBD_SAT_UNDEC;
	if ( status == l_True )
	break;
	assert( status == l_False );
	// compute cube and add clause
	nFinal = sat_solver_final( pSat, &pFinal );
	uCube = ~(word)0;
	Vec_IntClear( vTemp );
	Vec_IntPush( vTemp, Abc_LitNot(pLits[1]) ); // NOT(iNewLit)
	for ( i = 0; i < nFinal; i++ )
	{
	if ( pFinal[i] == pLits[0] )
	continue;
	Vec_IntPush( vTemp, pFinal[i] );
	iVar = Vec_IntFind( vDivSet, Abc_Lit2Var(pFinal[i]) ); assert( iVar >= 0 );
	uCube &= Abc_LitIsCompl(pFinal[i]) ? s_Truths6[iVar] : ~s_Truths6[iVar];
	}
	uTruth \|= uCube;
	status = sat_solver_addclause( pSat, Vec_IntArray(vTemp), Vec_IntArray(vTemp) + Vec_IntSize(vTemp) );
	assert( status );
	nIter++;
	}
	assert( status == l_True );
	// store the counter-example
	Vec_IntForEachEntry( vDivVars, iVar, i )
	Vec_IntAddToEntry( vDivValues, i, sat_solver_var_value(pSat, iVar) );

	for ( i = 0; i < Vec_IntSize(vDivValues); i++ )
	Vec_IntAddToEntry( vDivValues, i, 0xC );
	/*
	// reduce the counter example
	for ( n = 0; n < 2; n++ )
	{
	Vec_IntClear( vTemp );
	Vec_IntPush( vTemp, Abc_Var2Lit(PivotVar, n) ); // n = 0 => F = 1 (expanding offset against onset)
	for ( i = 0; i < Vec_IntSize(vValues); i++ )
	Vec_IntPush( vTemp, Abc_Var2Lit(i, !((Vec_IntEntry(vValues, i) >> n) & 1)) );
	status = sat_solver_solve( pSat, Vec_IntArray(vTemp), Vec_IntArray(vTemp) + Vec_IntSize(vTemp), nBTLimit, 0, 0, 0 );
	assert( status == l_False );
	// compute cube and add clause
	nFinal = sat_solver_final( pSat, &pFinal );
	for ( i = 0; i < nFinal; i++ )
	if ( Abc_Lit2Var(pFinal[i]) != PivotVar )
	Vec_IntAddToEntry( vValues, Abc_Lit2Var(pFinal[i]), 1 << (n+2) );
	}
	*/
	return SBD_SAT_SAT;
	}

	/Function***********************************************************

	Synopsis []

	Description []

	SideEffects []

	SeeAlso []

	***********************************************************************/
	int Sbd_ManSolve2( sat_solver * pSat, int PivotVar, int FreeVar, Vec_Int_t * vDivVars, Vec_Int_t * vDivValues, Vec_Int_t * vTemp, Vec_Int_t * vSop )
	{
	int nBTLimit = 0;
	int status, i, iVar, nFinal, * pFinal, pLits[2], nIter = 0;
	assert( FreeVar < sat_solver_nvars(pSat) );
	assert( Vec_IntSize(vDivVars) == Vec_IntSize(vDivValues) );
	pLits[0] = Abc_Var2Lit( PivotVar, 0 ); // F = 1
	pLits[1] = Abc_Var2Lit( FreeVar, 0 ); // iNewLit
	Vec_IntClear( vSop );
	while ( 1 )
	{
	// find onset minterm
	status = sat_solver_solve( pSat, pLits, pLits + 2, nBTLimit, 0, 0, 0 );
	if ( status == l_Undef )
	return 0;
	if ( status == l_False )
	return 1;
	assert( status == l_True );
	// remember variable values
	//for ( i = 0; i < Vec_IntSize(vValues); i++ )
	// Vec_IntWriteEntry( vValues, i, 2*sat_solver_var_value(pSat, i) );
	// collect divisor literals
	Vec_IntClear( vTemp );
	Vec_IntPush( vTemp, Abc_LitNot(pLits[0]) ); // F = 0
	//Vec_IntForEachEntry( vDivSet, iVar, i )
	Vec_IntForEachEntry( vDivVars, iVar, i )
	Vec_IntPush( vTemp, sat_solver_var_literal(pSat, iVar) );
	// check against offset
	status = sat_solver_solve( pSat, Vec_IntArray(vTemp), Vec_IntArray(vTemp) + Vec_IntSize(vTemp), nBTLimit, 0, 0, 0 );
	if ( status == l_Undef )
	return 0;
	if ( status == l_True )
	break;
	assert( status == l_False );
	// compute cube and add clause
	nFinal = sat_solver_final( pSat, &pFinal );
	Vec_IntClear( vTemp );
	Vec_IntPush( vTemp, Abc_LitNot(pLits[1]) ); // NOT(iNewLit)
	for ( i = 0; i < nFinal; i++ )
	{
	if ( pFinal[i] == pLits[0] )
	continue;
	Vec_IntPush( vTemp, pFinal[i] );
	iVar = Vec_IntFind( vDivVars, Abc_Lit2Var(pFinal[i]) ); assert( iVar >= 0 );
	//uCube &= Abc_LitIsCompl(pFinal[i]) ? s_Truths6[iVar] : ~s_Truths6[iVar];
	Vec_IntPush( vSop, Abc_Var2Lit( iVar, !Abc_LitIsCompl(pFinal[i]) ) );
	}
	//uTruth \|= uCube;
	Vec_IntPush( vSop, -1 );
	status = sat_solver_addclause( pSat, Vec_IntArray(vTemp), Vec_IntArray(vTemp) + Vec_IntSize(vTemp) );
	assert( status );
	nIter++;
	}
	assert( status == l_True );
	// store the counter-example
	//for ( i = 0; i < Vec_IntSize(vValues); i++ )
	// Vec_IntAddToEntry( vValues, i, sat_solver_var_value(pSat, i) );
	return 0;
	}

	word Sbd_ManSolverSupp( Vec_Int_t * vSop, int * pInds, int * pnVars )
	{
	word Supp = 0;
	int i, Entry, nVars = 0;
	Vec_IntForEachEntry( vSop, Entry, i )
	{
	if ( Entry == -1 )
	continue;
	assert( Abc_Lit2Var(Entry) < 64 );
	if ( (Supp >> Abc_Lit2Var(Entry)) & 1 )
	continue;
	pInds[Abc_Lit2Var(Entry)] = nVars++;
	Supp \|= (word)1 << Abc_Lit2Var(Entry);
	}
	*pnVars = nVars;
	return Supp;
	}
	void Sbd_ManSolverPrint( Vec_Int_t * vSop )
	{
	int v, i, Entry, nVars, pInds[64];
	word Supp = Sbd_ManSolverSupp( vSop, pInds, &nVars );
	char Cube[65] = {'\0'};
	assert( Cube[nVars] == '\0' );
	for ( v = 0; v < nVars; v++ )
	Cube[v] = '-';
	Vec_IntForEachEntry( vSop, Entry, i )
	{
	if ( Entry == -1 )
	{
	printf( "%s\n", Cube );
	for ( v = 0; v < nVars; v++ )
	Cube[v] = '-';
	continue;
	}
	Cube[pInds[Abc_Lit2Var(Entry)]] = '1' - (char)Abc_LitIsCompl(Entry);
	}
	Supp = 0;
	}
	void Sbd_ManSolveSelect( Gia_Man_t * p, Vec_Int_t * vMirrors, int Pivot, Vec_Int_t * vDivVars, Vec_Int_t * vDivValues, Vec_Int_t * vWinObjs, Vec_Int_t * vObj2Var, Vec_Int_t * vTfo, Vec_Int_t * vRoots )
	{
	Vec_Int_t * vSop = Vec_IntAlloc( 100 );
	Vec_Int_t * vTemp = Vec_IntAlloc( 100 );
	sat_solver * pSat = Sbd_ManSatSolver( NULL, p, vMirrors, Pivot, vWinObjs, vObj2Var, vTfo, vRoots, 0 );
	int PivotVar = Vec_IntEntry(vObj2Var, Pivot);
	int FreeVar = Vec_IntSize(vWinObjs) + Vec_IntSize(vTfo) + Vec_IntSize(vRoots);
	int Status = Sbd_ManSolve2( pSat, PivotVar, FreeVar, vDivVars, vDivValues, vTemp, vSop );
	printf( "Pivot = %4d. Divs = %4d. ", Pivot, Vec_IntSize(vDivVars) );
	if ( Status == 0 )
	printf( "UNSAT.\n" );
	else
	{
	int nVars, pInds[64];
	word Supp = Sbd_ManSolverSupp( vSop, pInds, &nVars );
	//Sbd_ManSolverPrint( vSop );
	printf( "SAT with %d vars and %d cubes.\n", nVars, Vec_IntCountEntry(vSop, -1) );
	Supp = 0;
	}
	Vec_IntFree( vTemp );
	Vec_IntFree( vSop );
	sat_solver_delete( pSat );
	}


	/Function***********************************************************

	Synopsis [Returns a bunch of positive/negative random care minterms.]

	Description [Returns 0/1 if the functions is const 0/1.]

	SideEffects []

	SeeAlso []

	***********************************************************************/
	static void sat_solver_random_polarity(sat_solver* s)
	{
	int i, k;
	for ( i = 0; i < s->size; i += 64 )
	{
	word Polar = Gia_ManRandomW(0);
	for ( k = 0; k < 64 && (i << 6) + k < s->size; k++ )
	s->polarity[(i << 6) + k] = Abc_TtGetBit(&Polar, k);
	}
	}
	int Sbd_ManCollectConstants( sat_solver * pSat, int nCareMints[2], int PivotVar, word * pVarSims[], Vec_Int_t * vInds )
	{
	int nBTLimit = 0;
	int i, Ind;
	assert( Vec_IntSize(vInds) == nCareMints[0] + nCareMints[1] );
	Vec_IntForEachEntry( vInds, Ind, i )
	{
	int fOffSet = (int)(i < nCareMints[0]);
	int status, k, iLit = Abc_Var2Lit( PivotVar, fOffSet );
	sat_solver_random_polarity( pSat );
	status = sat_solver_solve( pSat, &iLit, &iLit + 1, nBTLimit, 0, 0, 0 );
	if ( status == l_Undef )
	return -2;
	if ( status == l_False )
	return fOffSet;
	for ( k = 0; k <= PivotVar; k++ )
	if ( Abc_TtGetBit(pVarSims[k], Ind) != sat_solver_var_value(pSat, k) )
	Abc_TtXorBit(pVarSims[k], Ind);
	}
	return -1;
	}

	int Sbd_ManCollectConstantsNew( sat_solver * pSat, Vec_Int_t * vDivVars, int nConsts, int PivotVar, word * pOnset, word * pOffset )
	{
	int nBTLimit = 0;
	int n, i, k, status, iLit, iVar;
	word * pPats[2] = {pOnset, pOffset};
	assert( Vec_IntSize(vDivVars) < 64 );
	for ( n = 0; n < 2; n++ )
	for ( i = 0; i < nConsts; i++ )
	{
	sat_solver_random_polarity( pSat );
	iLit = Abc_Var2Lit( PivotVar, n );
	status = sat_solver_solve( pSat, &iLit, &iLit + 1, nBTLimit, 0, 0, 0 );
	if ( status == l_Undef )
	return -2;
	if ( status == l_False )
	return n;
	pPats[n][i] = ((word)!n) << Vec_IntSize(vDivVars);
	Vec_IntForEachEntry( vDivVars, iVar, k )
	if ( sat_solver_var_value(pSat, iVar) )
	Abc_TtXorBit(&pPats[n][i], k);
	}
	return -1;
	}


	////////////////////////////////////////////////////////////////////////
	/// END OF FILE ///
	////////////////////////////////////////////////////////////////////////


	ABC_NAMESPACE_IMPL_END