New MFS package.

9 files changed, 96 insertions, 98 deletions

diff --git a/src/base/abci/abc.c b/src/base/abci/abc.c
index a171ce66..c51c53c5 100644
--- a/src/base/abci/abc.c
+++ b/src/base/abci/abc.c
@@ -4475,7 +4475,7 @@ int Abc_CommandMfs2( Abc_Frame_t * pAbc, int argc, char ** argv )
     // set defaults
     Sfm_ParSetDefault( pPars );
     Extra_UtilGetoptReset();
-    while ( ( c = Extra_UtilGetopt( argc, argv, "WFDMNCZdlaevwh" ) ) != EOF )
+    while ( ( c = Extra_UtilGetopt( argc, argv, "WFDMCZdlaevwh" ) ) != EOF )
     {
         switch ( c )
         {
@@ -4523,17 +4523,6 @@ int Abc_CommandMfs2( Abc_Frame_t * pAbc, int argc, char ** argv )
             if ( pPars->nWinSizeMax < 0 )
                 goto usage;
             break;
-        case 'N':
-            if ( globalUtilOptind >= argc )
-            {
-                Abc_Print( -1, "Command line switch \"-N\" should be followed by an integer.\n" );
-                goto usage;
-            }
-            pPars->nDivNumMax = atoi(argv[globalUtilOptind]);
-            globalUtilOptind++;
-            if ( pPars->nDivNumMax < 0 )
-                goto usage;
-            break;
         case 'C':
             if ( globalUtilOptind >= argc )
             {
@@ -4590,11 +4579,6 @@ int Abc_CommandMfs2( Abc_Frame_t * pAbc, int argc, char ** argv )
         Abc_Print( -1, "This command can only be applied to a logic network.\n" );
         return 1;
     }
-    if ( !Abc_NtkIsSopLogic(pNtk) )
-    {
-        Abc_Print( -1, "Currently this command works only for SOP logic networks (run \"sop\").\n" );
-        return 1;
-    }
     // modify the current network
     if ( !Abc_NtkPerformMfs( pNtk, pPars ) )
     {
@@ -4604,13 +4588,12 @@ int Abc_CommandMfs2( Abc_Frame_t * pAbc, int argc, char ** argv )
     return 0;
 
 usage:
-    Abc_Print( -2, "usage: mfs2 [-WFDMNCZ <num>] [-dlaevwh]\n" );
+    Abc_Print( -2, "usage: mfs2 [-WFDMCZ <num>] [-dlaevwh]\n" );
     Abc_Print( -2, "\t           performs don't-care-based optimization of logic networks\n" );
     Abc_Print( -2, "\t-W <num> : the number of levels in the TFO cone (0 <= num) [default = %d]\n", pPars->nTfoLevMax );
     Abc_Print( -2, "\t-F <num> : the max number of fanouts to skip (1 <= num) [default = %d]\n", pPars->nFanoutMax );
     Abc_Print( -2, "\t-D <num> : the max depth nodes to try (0 = no limit) [default = %d]\n", pPars->nDepthMax );
     Abc_Print( -2, "\t-M <num> : the max node count of windows to consider (0 = no limit) [default = %d]\n", pPars->nWinSizeMax );
-    Abc_Print( -2, "\t-N <num> : the max number of divisors to consider (0 = no limit) [default = %d]\n", pPars->nDivNumMax );
     Abc_Print( -2, "\t-C <num> : the max number of conflicts in one SAT run (0 = no limit) [default = %d]\n", pPars->nBTLimit );
     Abc_Print( -2, "\t-Z <num> : treat the first <num> logic nodes as fixed (0 = none) [default = %d]\n", pPars->nFirstFixed );
     Abc_Print( -2, "\t-d       : toggle performing redundancy removal [default = %s]\n", pPars->fRrOnly? "yes": "no" );
diff --git a/src/base/abci/abcMfs.c b/src/base/abci/abcMfs.c
index 3368fe5d..c87c1a75 100644
--- a/src/base/abci/abcMfs.c
+++ b/src/base/abci/abcMfs.c
@@ -51,16 +51,16 @@ Vec_Ptr_t * Abc_NtkAssignIDs( Abc_Ntk_t * pNtk )
     int i;
     vNodes = Abc_NtkDfs( pNtk, 0 );
     Abc_NtkCleanCopy( pNtk );
-    Abc_NtkForEachPi( pNtk, pObj, i )
+    Abc_NtkForEachCi( pNtk, pObj, i )
         pObj->iTemp = i;
     Vec_PtrForEachEntry( Abc_Obj_t *, vNodes, pObj, i )
     {
-        pObj->iTemp = Abc_NtkPiNum(pNtk) + i;
+        pObj->iTemp = Abc_NtkCiNum(pNtk) + i;
 //printf( "%d->%d ", pObj->Id, pObj->iTemp );
     }
 //printf( "\n" );
-    Abc_NtkForEachPo( pNtk, pObj, i )
-        pObj->iTemp = Abc_NtkPiNum(pNtk) + Vec_PtrSize(vNodes) + i;
+    Abc_NtkForEachCo( pNtk, pObj, i )
+        pObj->iTemp = Abc_NtkCiNum(pNtk) + Vec_PtrSize(vNodes) + i;
     return vNodes;
 }
 Vec_Ptr_t * Abc_NtkAssignIDs2( Abc_Ntk_t * pNtk )
@@ -69,16 +69,16 @@ Vec_Ptr_t * Abc_NtkAssignIDs2( Abc_Ntk_t * pNtk )
     Abc_Obj_t * pObj;
     int i;
     Abc_NtkCleanCopy( pNtk );
-    Abc_NtkForEachPi( pNtk, pObj, i )
+    Abc_NtkForEachCi( pNtk, pObj, i )
         pObj->iTemp = i;
     vNodes = Vec_PtrAlloc( Abc_NtkNodeNum(pNtk) );
     Abc_NtkForEachNode( pNtk, pObj, i )
     {
         Vec_PtrPush( vNodes, pObj );
-        pObj->iTemp = Abc_NtkPiNum(pNtk) + i;
+        pObj->iTemp = Abc_NtkCiNum(pNtk) + i;
     }
-    Abc_NtkForEachPo( pNtk, pObj, i )
-        pObj->iTemp = Abc_NtkPiNum(pNtk) + Vec_PtrSize(vNodes) + i;
+    Abc_NtkForEachCo( pNtk, pObj, i )
+        pObj->iTemp = Abc_NtkCiNum(pNtk) + Vec_PtrSize(vNodes) + i;
     return vNodes;
 }
 
@@ -103,19 +103,22 @@ Sfm_Ntk_t * Abc_NtkExtractMfs( Abc_Ntk_t * pNtk, int nFirstFixed )
     Abc_Obj_t * pObj, * pFanin;
     int i, k, nObjs;
     vNodes  = nFirstFixed ? Abc_NtkAssignIDs2(pNtk) : Abc_NtkAssignIDs(pNtk);
-    nObjs   = Abc_NtkPiNum(pNtk) + Vec_PtrSize(vNodes) + Abc_NtkPoNum(pNtk);
+    nObjs   = Abc_NtkCiNum(pNtk) + Vec_PtrSize(vNodes) + Abc_NtkCoNum(pNtk);
     vFanins = Vec_WecStart( nObjs );
     vFixed  = Vec_StrStart( nObjs );
     vTruths = Vec_WrdStart( nObjs );
     Vec_PtrForEachEntry( Abc_Obj_t *, vNodes, pObj, i )
     {
+        word uTruth = Abc_SopToTruth((char *)pObj->pData, Abc_ObjFaninNum(pObj));
+        Vec_WrdWriteEntry( vTruths, pObj->iTemp, uTruth );
         vArray = Vec_WecEntry( vFanins, pObj->iTemp );
+        if ( uTruth == 0 || ~uTruth == 0 )
+            continue;
         Vec_IntGrow( vArray, Abc_ObjFaninNum(pObj) );
         Abc_ObjForEachFanin( pObj, pFanin, k )
             Vec_IntPush( vArray, pFanin->iTemp );
-        Vec_WrdWriteEntry( vTruths, pObj->iTemp, Abc_SopToTruth((char *)pObj->pData, Abc_ObjFaninNum(pObj)) );
     }
-    Abc_NtkForEachPo( pNtk, pObj, i )
+    Abc_NtkForEachCo( pNtk, pObj, i )
     {
         vArray = Vec_WecEntry( vFanins, pObj->iTemp );
         Vec_IntGrow( vArray, Abc_ObjFaninNum(pObj) );
@@ -125,9 +128,9 @@ Sfm_Ntk_t * Abc_NtkExtractMfs( Abc_Ntk_t * pNtk, int nFirstFixed )
     Vec_PtrFree( vNodes );
     // update fixed
     assert( nFirstFixed >= 0 && nFirstFixed < Abc_NtkNodeNum(pNtk) );
-    for ( i = Abc_NtkPiNum(pNtk); i < Abc_NtkPiNum(pNtk) + nFirstFixed; i++ )
+    for ( i = Abc_NtkCiNum(pNtk); i < Abc_NtkCiNum(pNtk) + nFirstFixed; i++ )
         Vec_StrWriteEntry( vFixed, i, (char)1 );
-    return Sfm_NtkConstruct( vFanins, Abc_NtkPiNum(pNtk), Abc_NtkPoNum(pNtk), vFixed, vTruths );
+    return Sfm_NtkConstruct( vFanins, Abc_NtkCiNum(pNtk), Abc_NtkCoNum(pNtk), vFixed, vTruths );
 }
 
 /**Function*************************************************************
@@ -150,7 +153,7 @@ void Abc_NtkInsertMfs( Abc_Ntk_t * pNtk, Sfm_Ntk_t * p )
     word * pTruth;
     // map new IDs into old nodes
     vMap = Vec_IntStart( Abc_NtkObjNumMax(pNtk) );
-    Abc_NtkForEachPi( pNtk, pNode, i )
+    Abc_NtkForEachCi( pNtk, pNode, i )
         Vec_IntWriteEntry( vMap, pNode->iTemp, Abc_ObjId(pNode) );
     Abc_NtkForEachNode( pNtk, pNode, i )
         if ( pNode->iTemp > 0 )
@@ -180,13 +183,14 @@ void Abc_NtkInsertMfs( Abc_Ntk_t * pNtk, Sfm_Ntk_t * p )
             pNode->pData = Abc_SopRegister( (Mem_Flex_t *)pNtk->pManFunc, " 1\n" );
         else
         {
-//            pNode->pData = Abc_SopCreateFromTruth( (Mem_Flex_t *)pNtk->pManFunc, Vec_IntSize(vArray), (unsigned *)pTruth );
             int RetValue = Kit_TruthIsop( (unsigned *)pTruth, Vec_IntSize(vArray), vCover, 1 );
+            assert( Vec_IntSize(vArray) > 0 );
             assert( RetValue == 0 || RetValue == 1 );
             pNode->pData = Abc_SopCreateFromIsop( (Mem_Flex_t *)pNtk->pManFunc, Vec_IntSize(vArray), vCover );
             if ( RetValue )
                 Abc_SopComplement( (char *)pNode->pData );
         }
+        assert( Abc_SopGetVarNum((char *)pNode->pData) == Vec_IntSize(vArray) );
     }
     Vec_IntFree( vMap );
 }
@@ -206,7 +210,7 @@ int Abc_NtkPerformMfs( Abc_Ntk_t * pNtk, Sfm_Par_t * pPars )
 {
     Sfm_Ntk_t * p;
     int nFaninMax, nNodes;
-    assert( Abc_NtkIsSopLogic(pNtk) );
+    assert( Abc_NtkIsLogic(pNtk) );
     // count fanouts
     nFaninMax = Abc_NtkGetFaninMax( pNtk );
     if ( nFaninMax > 6 )
@@ -214,6 +218,8 @@ int Abc_NtkPerformMfs( Abc_Ntk_t * pNtk, Sfm_Par_t * pPars )
         Abc_Print( 1, "Currently \"mfs\" cannot process the network containing nodes with more than 6 fanins.\n" );
         return 0;
     }
+    if ( !Abc_NtkHasSop(pNtk) )
+        Abc_NtkToSop( pNtk, 0 );
     // collect information
     p = Abc_NtkExtractMfs( pNtk, pPars->nFirstFixed );
     // perform optimization
@@ -224,7 +230,8 @@ int Abc_NtkPerformMfs( Abc_Ntk_t * pNtk, Sfm_Par_t * pPars )
     else
     {
         Abc_NtkInsertMfs( pNtk, p );
-        Abc_Print( 1, "The network has %d nodes changed by \"mfs\".\n", nNodes );
+        if( pPars->fVerbose )
+            Abc_Print( 1, "The network has %d nodes changed by \"mfs\".\n", nNodes );
     }
     Sfm_NtkFree( p );
     return 1;
diff --git a/src/opt/mfs/mfsMan.c b/src/opt/mfs/mfsMan.c
index 401c6edd..6042f15e 100644
--- a/src/opt/mfs/mfsMan.c
+++ b/src/opt/mfs/mfsMan.c
@@ -121,8 +121,8 @@ void Mfs_ManPrint( Mfs_Man_t * p )
         printf( "\n" );
 
         printf( "Reduction:   " );
-        printf( "Nodes  %6d out of %6d (%6.2f %%)   ", p->nTotalNodesBeg-p->nTotalNodesEnd, p->nTotalNodesEnd, 100.0*(p->nTotalNodesBeg-p->nTotalNodesEnd)/Abc_MaxInt(1, p->nTotalNodesBeg) );
-        printf( "Edges  %6d out of %6d (%6.2f %%)   ", p->nTotalEdgesBeg-p->nTotalEdgesEnd, p->nTotalEdgesEnd, 100.0*(p->nTotalEdgesBeg-p->nTotalEdgesEnd)/Abc_MaxInt(1, p->nTotalEdgesBeg) );
+        printf( "Nodes  %6d out of %6d (%6.2f %%)   ", p->nTotalNodesBeg-p->nTotalNodesEnd, p->nTotalNodesBeg, 100.0*(p->nTotalNodesBeg-p->nTotalNodesEnd)/Abc_MaxInt(1, p->nTotalNodesBeg) );
+        printf( "Edges  %6d out of %6d (%6.2f %%)   ", p->nTotalEdgesBeg-p->nTotalEdgesEnd, p->nTotalEdgesBeg, 100.0*(p->nTotalEdgesBeg-p->nTotalEdgesEnd)/Abc_MaxInt(1, p->nTotalEdgesBeg) );
         printf( "\n" );
 
         if (p->pPars->fPower)
diff --git a/src/opt/sfm/sfm.h b/src/opt/sfm/sfm.h
index 025d0dfa..9323aa47 100644
--- a/src/opt/sfm/sfm.h
+++ b/src/opt/sfm/sfm.h
@@ -46,7 +46,6 @@ struct Sfm_Par_t_
     int             nFanoutMax;    // the maximum number of fanouts
     int             nDepthMax;     // the maximum depth to try
     int             nWinSizeMax;   // the maximum window size
-    int             nDivNumMax;    // the maximum number of divisors
     int             nBTLimit;      // the maximum number of conflicts in one SAT run
     int             nFirstFixed;   // the number of first nodes to be treated as fixed
     int             fFixLevel;     // does not allow level to increase
diff --git a/src/opt/sfm/sfmCnf.c b/src/opt/sfm/sfmCnf.c
index f04a6970..02744cf4 100644
--- a/src/opt/sfm/sfmCnf.c
+++ b/src/opt/sfm/sfmCnf.c
@@ -73,6 +73,7 @@ int Sfm_TruthToCnf( word Truth, int nVars, Vec_Int_t * vCover, Vec_Str_t * vCnf
     Vec_StrClear( vCnf );
     if ( Truth == 0 || ~Truth == 0 )
     {
+//        assert( nVars == 0 );
         Vec_StrPush( vCnf, (char)(Truth == 0) );
         Vec_StrPush( vCnf, (char)-1 );
         return 1;
@@ -80,6 +81,7 @@ int Sfm_TruthToCnf( word Truth, int nVars, Vec_Int_t * vCover, Vec_Str_t * vCnf
     else 
     {
         int i, k, c, RetValue, Literal, Cube, nCubes = 0;
+        assert( nVars > 0 );
         for ( c = 0; c < 2; c ++ )
         {
             Truth = c ? ~Truth : Truth;
@@ -159,11 +161,9 @@ void Sfm_TranslateCnf( Vec_Wec_t * vRes, Vec_Str_t * vCnf, Vec_Int_t * vFaninMap
     {
         Lit = (int)Entry;
         if ( Lit == -1 )
-        {
             vClause = Vec_WecPushLevel( vRes );
-            continue;
-        }
-        Vec_IntPush( vClause, Abc_Lit2LitV( Vec_IntArray(vFaninMap), Lit ) );
+        else
+            Vec_IntPush( vClause, Abc_Lit2LitV( Vec_IntArray(vFaninMap), Lit ) );
     }
 }
 
diff --git a/src/opt/sfm/sfmCore.c b/src/opt/sfm/sfmCore.c
index 67cbaa3a..92f94562 100644
--- a/src/opt/sfm/sfmCore.c
+++ b/src/opt/sfm/sfmCore.c
@@ -49,7 +49,6 @@ void Sfm_ParSetDefault( Sfm_Par_t * pPars )
     pPars->nFanoutMax   =   30;  // the maximum number of fanouts
     pPars->nDepthMax    =   20;  // the maximum depth to try  
     pPars->nWinSizeMax  =  300;  // the maximum window size
-    pPars->nDivNumMax   =  300;  // the maximum number of divisors
     pPars->nBTLimit     =    0;  // the maximum number of conflicts in one SAT run
     pPars->fFixLevel    =    1;  // does not allow level to increase
     pPars->fRrOnly      =    0;  // perform redundancy removal
@@ -82,8 +81,8 @@ void Sfm_NtkPrintStats( Sfm_Ntk_t * p )
     printf( "\n" );
 
     printf( "Reduction:   " );
-    printf( "Nodes  %6d out of %6d (%6.2f %%)   ", p->nTotalNodesBeg-p->nTotalNodesEnd, p->nTotalNodesEnd, 100.0*(p->nTotalNodesBeg-p->nTotalNodesEnd)/Abc_MaxInt(1, p->nTotalNodesBeg) );
-    printf( "Edges  %6d out of %6d (%6.2f %%)   ", p->nTotalEdgesBeg-p->nTotalEdgesEnd, p->nTotalEdgesEnd, 100.0*(p->nTotalEdgesBeg-p->nTotalEdgesEnd)/Abc_MaxInt(1, p->nTotalEdgesBeg) );
+    printf( "Nodes  %6d out of %6d (%6.2f %%)   ", p->nTotalNodesBeg-p->nTotalNodesEnd, p->nTotalNodesBeg, 100.0*(p->nTotalNodesBeg-p->nTotalNodesEnd)/Abc_MaxInt(1, p->nTotalNodesBeg) );
+    printf( "Edges  %6d out of %6d (%6.2f %%)   ", p->nTotalEdgesBeg-p->nTotalEdgesEnd, p->nTotalEdgesBeg, 100.0*(p->nTotalEdgesBeg-p->nTotalEdgesEnd)/Abc_MaxInt(1, p->nTotalEdgesBeg) );
     printf( "\n" );
 
     ABC_PRTP( "Win", p->timeWin  ,  p->timeTotal );
@@ -254,14 +253,14 @@ int Sfm_NodeResub( Sfm_Ntk_t * p, int iNode )
 ***********************************************************************/
 int Sfm_NtkPerform( Sfm_Ntk_t * p, Sfm_Par_t * pPars )
 {
-    int i, Counter = 0;
+    int i, k, Counter = 0;
     p->timeTotal = clock();
     p->pPars = pPars;
     Sfm_NtkPrepare( p );
 //    Sfm_ComputeInterpolantCheck( p );
 //    return 0;
-    p->nTotalNodesBeg = Vec_WecSizeUsed(&p->vFanins) - Sfm_NtkPoNum(p);
-    p->nTotalEdgesBeg = Vec_WecSizeSize(&p->vFanins);
+    p->nTotalNodesBeg = Vec_WecSize(&p->vFanins) - Sfm_NtkPiNum(p) - Sfm_NtkPoNum(p);
+    p->nTotalEdgesBeg = Vec_WecSizeSize(&p->vFanins) - Sfm_NtkPoNum(p);
     Sfm_NtkForEachNode( p, i )
     {
         if ( Sfm_ObjIsFixed( p, i ) )
@@ -270,11 +269,12 @@ int Sfm_NtkPerform( Sfm_Ntk_t * p, Sfm_Par_t * pPars )
             continue;
         if ( Sfm_ObjFaninNum(p, i) < 2 || Sfm_ObjFaninNum(p, i) > 6 )
             continue;
-        while ( Sfm_NodeResub(p, i) )
-            Counter++;
+        for ( k = 0; Sfm_NodeResub(p, i); k++ )
+            ;
+        Counter += (k > 0);
     }
     p->nTotalNodesEnd = Vec_WecSizeUsed(&p->vFanins) - Sfm_NtkPoNum(p);
-    p->nTotalEdgesEnd = Vec_WecSizeSize(&p->vFanins);
+    p->nTotalEdgesEnd = Vec_WecSizeSize(&p->vFanins) - Sfm_NtkPoNum(p);
     p->timeTotal = clock() - p->timeTotal;
     if ( pPars->fVerbose )
         Sfm_NtkPrintStats( p );
diff --git a/src/opt/sfm/sfmNtk.c b/src/opt/sfm/sfmNtk.c
index 3783e368..79b7bb6a 100644
--- a/src/opt/sfm/sfmNtk.c
+++ b/src/opt/sfm/sfmNtk.c
@@ -168,7 +168,7 @@ void Sfm_NtkPrepare( Sfm_Ntk_t * p )
     p->vDivs     = Vec_IntAlloc( 100 );
     p->vRoots    = Vec_IntAlloc( 1000 );
     p->vTfo      = Vec_IntAlloc( 1000 );
-    p->vDivCexes = Vec_WrdStart( p->pPars->nDivNumMax );
+    p->vDivCexes = Vec_WrdStart( p->pPars->nWinSizeMax );
     p->vOrder    = Vec_IntAlloc( 100 );
     p->vDivVars  = Vec_IntAlloc( 100 );
     p->vDivIds   = Vec_IntAlloc( 1000 );
@@ -177,6 +177,7 @@ void Sfm_NtkPrepare( Sfm_Ntk_t * p )
     p->vClauses  = Vec_WecAlloc( 100 );
     p->vFaninMap = Vec_IntAlloc( 10 );
     p->pSat      = sat_solver_new();
+    sat_solver_setnvars( p->pSat, p->pPars->nWinSizeMax );
 }
 void Sfm_NtkFree( Sfm_Ntk_t * p )
 {
@@ -226,6 +227,8 @@ void Sfm_NtkFree( Sfm_Ntk_t * p )
 void Sfm_NtkRemoveFanin( Sfm_Ntk_t * p, int iNode, int iFanin )
 {
     int RetValue;
+    assert( Sfm_ObjIsNode(p, iNode) );
+    assert( !Sfm_ObjIsPo(p, iFanin) );
     RetValue = Vec_IntRemove( Sfm_ObjFiArray(p, iNode), iFanin );
     assert( RetValue );
     RetValue = Vec_IntRemove( Sfm_ObjFoArray(p, iFanin), iNode );
@@ -235,6 +238,8 @@ void Sfm_NtkAddFanin( Sfm_Ntk_t * p, int iNode, int iFanin )
 {
     if ( iFanin < 0 )
         return;
+    assert( Sfm_ObjIsNode(p, iNode) );
+    assert( !Sfm_ObjIsPo(p, iFanin) );
     assert( Vec_IntFind( Sfm_ObjFiArray(p, iNode), iFanin ) == -1 );
     assert( Vec_IntFind( Sfm_ObjFoArray(p, iFanin), iNode ) == -1 );
     Vec_IntPush( Sfm_ObjFiArray(p, iNode), iFanin );
@@ -268,13 +273,26 @@ void Sfm_NtkUpdateLevel_rec( Sfm_Ntk_t * p, int iNode )
 void Sfm_NtkUpdate( Sfm_Ntk_t * p, int iNode, int f, int iFaninNew, word uTruth )
 {
     int iFanin = Sfm_ObjFanin( p, iNode, f );
-    assert( iFanin != iFaninNew );
-    // replace old fanin by new fanin
     assert( Sfm_ObjIsNode(p, iNode) );
-    Sfm_NtkRemoveFanin( p, iNode, iFanin );
-    Sfm_NtkAddFanin( p, iNode, iFaninNew );
-    // recursively remove MFFC
-    Sfm_NtkDeleteObj_rec( p, iFanin );
+    assert( iFanin != iFaninNew );
+    if ( uTruth == 0 || ~uTruth == 0 )
+    {
+        Sfm_ObjForEachFanin( p, iNode, iFanin, f )
+        {
+            int RetValue = Vec_IntRemove( Sfm_ObjFoArray(p, iFanin), iNode );  assert( RetValue );
+            if ( Sfm_ObjFanoutNum(p, iFanin) == 0 )
+                Sfm_NtkDeleteObj_rec( p, iFanin );
+        }
+        Vec_IntClear( Sfm_ObjFiArray(p, iNode) );
+    }
+    else
+    {
+        // replace old fanin by new fanin
+        Sfm_NtkRemoveFanin( p, iNode, iFanin );
+        Sfm_NtkAddFanin( p, iNode, iFaninNew );
+        // recursively remove MFFC
+        Sfm_NtkDeleteObj_rec( p, iFanin );
+    }
     // update logic level
     Sfm_NtkUpdateLevel_rec( p, iNode );
     // update truth table
diff --git a/src/opt/sfm/sfmSat.c b/src/opt/sfm/sfmSat.c
index bf6a06b0..01b9d4cf 100644
--- a/src/opt/sfm/sfmSat.c
+++ b/src/opt/sfm/sfmSat.c
@@ -59,7 +59,7 @@ void Sfm_NtkWindowToSolver( Sfm_Ntk_t * p )
 //    if ( p->pSat )
 //        printf( "%d  ", p->pSat->stats.learnts );
     sat_solver_restart( p->pSat );
-    sat_solver_setnvars( p->pSat, 1 + Vec_IntSize(p->vDivs) + 2 * Vec_IntSize(p->vTfo) + Vec_IntSize(p->vRoots) + 100 );
+    sat_solver_setnvars( p->pSat, 1 + Vec_IntSize(p->vDivs) + 2 * Vec_IntSize(p->vTfo) + Vec_IntSize(p->vRoots) + 50 );
     // create SAT variables
     Sfm_NtkCleanVars( p );
     p->nSatVars = 1;
diff --git a/src/opt/sfm/sfmWin.c b/src/opt/sfm/sfmWin.c
index 1d2919f9..8ddd7865 100644
--- a/src/opt/sfm/sfmWin.c
+++ b/src/opt/sfm/sfmWin.c
@@ -192,7 +192,7 @@ void Sfm_NtkAddDivisors( Sfm_Ntk_t * p, int iNode, int nLevelMax )
         if ( p->pPars->nFanoutMax && i > p->pPars->nFanoutMax )
             break;
         // skip TFI nodes, PO nodes, or nodes with high logic level
-        if ( Sfm_ObjIsTravIdCurrent(p, iFanout) || Sfm_ObjIsPo(p, iFanout) || 
+        if ( Sfm_ObjIsTravIdCurrent(p, iFanout) || Sfm_ObjIsPo(p, iFanout) || Sfm_ObjIsFixed(p, iFanout) ||
             (p->pPars->fFixLevel && Sfm_ObjLevel(p, iFanout) >= nLevelMax) )
             continue;
         // handle single-input nodes
@@ -241,7 +241,7 @@ int Sfm_NtkCollectTfi_rec( Sfm_Ntk_t * p, int iNode, int nWinSizeMax )
 }
 int Sfm_NtkCreateWindow( Sfm_Ntk_t * p, int iNode, int fVerbose )
 {
-    int i, iTemp;
+    int i, k, iTemp, nDivStart;
     clock_t clk = clock();
     assert( Sfm_ObjIsNode( p, iNode ) );
     Vec_IntClear( p->vLeaves ); // leaves 
@@ -272,56 +272,47 @@ int Sfm_NtkCreateWindow( Sfm_Ntk_t * p, int iNode, int fVerbose )
         Vec_IntPush( p->vRoots, iNode );
     p->timeWin += clock() - clk;
     clk = clock();
+    // create divisors
+    Vec_IntClear( p->vDivs );
+    Vec_IntForEachEntry( p->vLeaves, iTemp, i )
+        Vec_IntPush( p->vDivs, iTemp );
+    Vec_IntForEachEntry( p->vNodes, iTemp, i )
+        Vec_IntPush( p->vDivs, iTemp );
+    Vec_IntPop( p->vDivs );
+    // add non-topological divisors
+    nDivStart = Vec_IntSize(p->vDivs);
+    if ( Vec_IntSize(p->vDivs) < p->pPars->nWinSizeMax )
+    {
+        Sfm_NtkIncrementTravId2( p );
+        Vec_IntForEachEntry( p->vDivs, iTemp, i )
+            if ( Vec_IntSize(p->vDivs) < p->pPars->nWinSizeMax )
+                Sfm_NtkAddDivisors( p, iTemp, Sfm_ObjLevel(p, iNode) );
+    }
+    if ( Vec_IntSize(p->vDivs) > p->pPars->nWinSizeMax )
+        Vec_IntShrink( p->vDivs, p->pPars->nWinSizeMax );
+    assert( Vec_IntSize(p->vDivs) <= p->pPars->nWinSizeMax );
+    p->nMaxDivs += (Vec_IntSize(p->vDivs) == p->pPars->nWinSizeMax);
     // create ordering of the nodes
     Vec_IntClear( p->vOrder );
     Vec_IntForEachEntryReverse( p->vNodes, iTemp, i )
         Vec_IntPush( p->vOrder, iTemp );
     Vec_IntForEachEntry( p->vLeaves, iTemp, i )
         Vec_IntPush( p->vOrder, iTemp );
+    Vec_IntForEachEntryStart( p->vDivs, iTemp, i, nDivStart )
+        Vec_IntPush( p->vOrder, iTemp );
+    // remove fanins from divisors
     // mark fanins
     Sfm_NtkIncrementTravId2( p );
     Sfm_ObjSetTravIdCurrent2( p, iNode );
     Sfm_ObjForEachFanin( p, iNode, iTemp, i )
         Sfm_ObjSetTravIdCurrent2( p, iTemp );
     // compact divisors
-    Vec_IntClear( p->vDivs );
-    Vec_IntForEachEntry( p->vLeaves, iTemp, i )
+    k = 0;
+    Vec_IntForEachEntry( p->vDivs, iTemp, i )
         if ( !Sfm_ObjIsTravIdCurrent2( p, iTemp ) )
-            Vec_IntPush( p->vDivs, iTemp );
-    Vec_IntForEachEntry( p->vNodes, iTemp, i )
-        if ( !Sfm_ObjIsTravIdCurrent2( p, iTemp ) )
-            Vec_IntPush( p->vDivs, iTemp );
-    // if we exceed the limit, remove the first few
-    if ( Vec_IntSize(p->vDivs) > p->pPars->nDivNumMax )
-    {
-        int k = 0;
-        Vec_IntForEachEntryStart( p->vDivs, iTemp, i, Vec_IntSize(p->vDivs) - p->pPars->nDivNumMax )
             Vec_IntWriteEntry( p->vDivs, k++, iTemp );
-        Vec_IntShrink( p->vDivs, k );
-        assert( Vec_IntSize(p->vDivs) == p->pPars->nDivNumMax );
-    }
-//Vec_IntPrint( p->vLeaves );
-//Vec_IntPrint( p->vNodes );
-//Vec_IntPrint( p->vDivs );
-    // collect additional divisors of the TFI nodes
-    if ( Vec_IntSize(p->vDivs) < p->pPars->nDivNumMax )
-    {
-        int nStartNew = Vec_IntSize(p->vDivs);
-        Sfm_NtkIncrementTravId2( p );
-        Sfm_ObjForEachFanin( p, iNode, iTemp, i )
-            if ( Vec_IntSize(p->vDivs) < p->pPars->nDivNumMax )
-                Sfm_NtkAddDivisors( p, iTemp, Sfm_ObjLevel(p, iNode) );
-        Vec_IntForEachEntry( p->vDivs, iTemp, i )
-            if ( Vec_IntSize(p->vDivs) < p->pPars->nDivNumMax )
-                Sfm_NtkAddDivisors( p, iTemp, Sfm_ObjLevel(p, iNode) );
-        if ( Vec_IntSize(p->vDivs) > p->pPars->nDivNumMax )
-            Vec_IntShrink( p->vDivs, p->pPars->nDivNumMax );
-        // add new divisor variable to the order
-        Vec_IntForEachEntryStart( p->vDivs, iTemp, i, nStartNew )
-            Vec_IntPush( p->vOrder, iTemp );
-    }
-    assert( Vec_IntSize(p->vDivs) <= p->pPars->nDivNumMax );
-    p->nMaxDivs += (Vec_IntSize(p->vDivs) == p->pPars->nDivNumMax);
+    Vec_IntShrink( p->vDivs, k );
+    assert( Vec_IntSize(p->vDivs) <= p->pPars->nWinSizeMax );
     // statistics
     p->nTotalDivs += Vec_IntSize(p->vDivs);
     p->timeDiv += clock() - clk;