summaryrefslogtreecommitdiffstats
path: root/src/aig/ivy/ivyRwrAlg.c
blob: ce60500307f6d459a396b2c1be5430816f9090a2 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
/**CFile****************************************************************

  FileName    [ivyRwrAlg.c]

  SystemName  [ABC: Logic synthesis and verification system.]

  PackageName [And-Inverter Graph package.]

  Synopsis    [Algebraic AIG rewriting.]

  Author      [Alan Mishchenko]
  
  Affiliation [UC Berkeley]

  Date        [Ver. 1.0. Started - May 11, 2006.]

  Revision    [$Id: ivyRwrAlg.c,v 1.00 2006/05/11 00:00:00 alanmi Exp $]

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

#include "ivy.h"

ABC_NAMESPACE_IMPL_START


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

static int Ivy_ManFindAlgCut( Ivy_Obj_t * pRoot, Vec_Ptr_t * vFront, Vec_Ptr_t * vLeaves, Vec_Ptr_t * vCone );
static Ivy_Obj_t * Ivy_NodeRewriteAlg( Ivy_Obj_t * pObj, Vec_Ptr_t * vFront, Vec_Ptr_t * vLeaves, Vec_Ptr_t * vCone, Vec_Ptr_t * vSols, int LevelR, int fUseZeroCost );
static int Ivy_NodeCountMffc( Ivy_Obj_t * pNode );

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

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

  Synopsis    [Algebraic AIG rewriting.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
int Ivy_ManRewriteAlg( Ivy_Man_t * p, int fUpdateLevel, int fUseZeroCost )
{
    Vec_Int_t * vRequired;
    Vec_Ptr_t * vFront, * vLeaves, * vCone, * vSol;
    Ivy_Obj_t * pObj, * pResult;
    int i, RetValue, LevelR, nNodesOld;
    int CountUsed, CountUndo;
    vRequired = fUpdateLevel? Ivy_ManRequiredLevels( p ) : NULL;
    vFront    = Vec_PtrAlloc( 100 );
    vLeaves   = Vec_PtrAlloc( 100 );
    vCone     = Vec_PtrAlloc( 100 );
    vSol      = Vec_PtrAlloc( 100 );
    // go through the nodes in the topological order
    CountUsed = CountUndo = 0;
    nNodesOld = Ivy_ManObjIdNext(p);
    Ivy_ManForEachObj( p, pObj, i )
    {
        assert( !Ivy_ObjIsBuf(pObj) );
        if ( i >= nNodesOld )
            break;
        // skip no-nodes and MUX roots
        if ( !Ivy_ObjIsNode(pObj) || Ivy_ObjIsExor(pObj) || Ivy_ObjIsMuxType(pObj) )
            continue;
//        if ( pObj->Id > 297 ) // 296 --- 297 
//            break;
        if ( pObj->Id == 297 )
        {
            int x = 0;
        }
        // get the largest algebraic cut
        RetValue = Ivy_ManFindAlgCut( pObj, vFront, vLeaves, vCone );
        // the case of a trivial tree cut
        if ( RetValue == 1 )
            continue;
        // the case of constant 0 cone
        if ( RetValue == -1 )
        {
            Ivy_ObjReplace( pObj, Ivy_ManConst0(p), 1, 0, 1 ); 
            continue;
        }
        assert( Vec_PtrSize(vLeaves) > 2 );
        // get the required level for this node
        LevelR = vRequired? Vec_IntEntry(vRequired, pObj->Id) : 1000000;
        // create a new cone
        pResult = Ivy_NodeRewriteAlg( pObj, vFront, vLeaves, vCone, vSol, LevelR, fUseZeroCost );
        if ( pResult == NULL || pResult == pObj )
            continue;
        assert( Vec_PtrSize(vSol) == 1 || !Ivy_IsComplement(pResult) );
        if ( Ivy_ObjLevel(Ivy_Regular(pResult)) > LevelR && Ivy_ObjRefs(Ivy_Regular(pResult)) == 0 )
            Ivy_ObjDelete_rec(Ivy_Regular(pResult), 1), CountUndo++;
        else
            Ivy_ObjReplace( pObj, pResult, 1, 0, 1 ), CountUsed++; 
    }
    printf( "Used = %d. Undo = %d.\n", CountUsed, CountUndo );
    Vec_PtrFree( vFront );
    Vec_PtrFree( vCone );
    Vec_PtrFree( vSol );
    if ( vRequired ) Vec_IntFree( vRequired );
    if ( i = Ivy_ManCleanup(p) )
        printf( "Cleanup after rewriting removed %d dangling nodes.\n", i );
    if ( !Ivy_ManCheck(p) )
        printf( "Ivy_ManRewriteAlg(): The check has failed.\n" );
    return 1;
}

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

  Synopsis    [Analizes one node.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
Ivy_Obj_t * Ivy_NodeRewriteAlg( Ivy_Obj_t * pObj, Vec_Ptr_t * vFront, Vec_Ptr_t * vLeaves, Vec_Ptr_t * vCone, Vec_Ptr_t * vSols, int LevelR, int fUseZeroCost )
{
    int fVerbose = 0;
    Ivy_Obj_t * pTemp;
    int k, Counter, nMffc, RetValue;

    if ( fVerbose )
    {
        if ( Ivy_ObjIsExor(pObj) )
            printf( "x " );
        else
            printf( "  " );
    }

/*       
    printf( "%d ", Vec_PtrSize(vFront) );
    printf( "( " );
    Vec_PtrForEachEntry( Ivy_Obj_t *, vFront, pTemp, k )
        printf( "%d ", Ivy_ObjRefs(Ivy_Regular(pTemp)) );
    printf( ")\n" );
*/
    // collect nodes in the cone
    if ( Ivy_ObjIsExor(pObj) )
        Ivy_ManCollectCone( pObj, vFront, vCone );
    else
        Ivy_ManCollectCone( pObj, vLeaves, vCone );

    // deref nodes in the cone
    Vec_PtrForEachEntry( Ivy_Obj_t *, vCone, pTemp, k )
    {
        Ivy_ObjRefsDec( Ivy_ObjFanin0(pTemp) );
        Ivy_ObjRefsDec( Ivy_ObjFanin1(pTemp) );
        pTemp->fMarkB = 1;
    }

    // count the MFFC size
    Vec_PtrForEachEntry( Ivy_Obj_t *, vFront, pTemp, k )
        Ivy_Regular(pTemp)->fMarkA = 1;
    nMffc = Ivy_NodeCountMffc( pObj );
    Vec_PtrForEachEntry( Ivy_Obj_t *, vFront, pTemp, k )
        Ivy_Regular(pTemp)->fMarkA = 0;

    if ( fVerbose )
    {
    Counter = 0;
    Vec_PtrForEachEntry( Ivy_Obj_t *, vCone, pTemp, k )
        Counter += (Ivy_ObjRefs(pTemp) > 0);
    printf( "%5d : Leaves = %2d. Cone = %2d. ConeRef = %2d.   Mffc = %d.   Lev = %d.  LevR = %d.\n", 
        pObj->Id, Vec_PtrSize(vFront), Vec_PtrSize(vCone), Counter-1, nMffc, Ivy_ObjLevel(pObj), LevelR );
    }
/*
    printf( "Leaves:" );
    Vec_PtrForEachEntry( Ivy_Obj_t *, vLeaves, pTemp, k )
        printf( " %d%s", Ivy_Regular(pTemp)->Id, Ivy_IsComplement(pTemp)? "\'" : "" );
    printf( "\n" );
    printf( "Cone:\n" );
    Vec_PtrForEachEntry( Ivy_Obj_t *, vCone, pTemp, k )
        printf( " %5d = %d%s %d%s\n", pTemp->Id,
            Ivy_ObjFaninId0(pTemp), Ivy_ObjFaninC0(pTemp)? "\'" : "",
            Ivy_ObjFaninId1(pTemp), Ivy_ObjFaninC1(pTemp)? "\'" : "" );
*/

    RetValue = Ivy_MultiPlus( vLeaves, vCone, Ivy_ObjType(pObj), nMffc + fUseZeroCost, vSols );

    // ref nodes in the cone
    Vec_PtrForEachEntry( Ivy_Obj_t *, vCone, pTemp, k )
    {
        Ivy_ObjRefsInc( Ivy_ObjFanin0(pTemp) );
        Ivy_ObjRefsInc( Ivy_ObjFanin1(pTemp) );
        pTemp->fMarkA = 0;
        pTemp->fMarkB = 0;
    }

    if ( !RetValue )
        return NULL;

    if ( Vec_PtrSize( vSols ) == 1 )
        return Vec_PtrEntry( vSols, 0 );
    return Ivy_NodeBalanceBuildSuper( vSols, Ivy_ObjType(pObj), 1 );
}

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

  Synopsis    [Comparison for node pointers.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
int Ivy_NodeCountMffc_rec( Ivy_Obj_t * pNode )
{
    if ( Ivy_ObjRefs(pNode) > 0 || Ivy_ObjIsCi(pNode) || pNode->fMarkA )
        return 0;
    assert( pNode->fMarkB );
    pNode->fMarkA = 1;
//    printf( "%d ", pNode->Id );
    if ( Ivy_ObjIsBuf(pNode) )
        return Ivy_NodeCountMffc_rec( Ivy_ObjFanin0(pNode) );
    return 1 + Ivy_NodeCountMffc_rec( Ivy_ObjFanin0(pNode) ) + Ivy_NodeCountMffc_rec( Ivy_ObjFanin1(pNode) );
}

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

  Synopsis    [Comparison for node pointers.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
int Ivy_NodeCountMffc( Ivy_Obj_t * pNode )
{
    assert( pNode->fMarkB );
    return 1 + Ivy_NodeCountMffc_rec( Ivy_ObjFanin0(pNode) ) + Ivy_NodeCountMffc_rec( Ivy_ObjFanin1(pNode) );
}

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

  Synopsis    [Comparison for node pointers.]

  Description []
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
int Ivy_ManFindAlgCutCompare( Ivy_Obj_t ** pp1, Ivy_Obj_t ** pp2 )
{
    if ( *pp1 < *pp2 )
        return -1;
    if ( *pp1 > *pp2 )
        return 1;
    return 0;
}

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

  Synopsis    [Computing one algebraic cut.]

  Description [Returns 1 if the tree-leaves of this node where traversed 
  and found to have no external references (and have not been collected). 
  Returns 0 if the tree-leaves have external references and are collected.]
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
int Ivy_ManFindAlgCut_rec( Ivy_Obj_t * pObj, Ivy_Type_t Type, Vec_Ptr_t * vFront, Vec_Ptr_t * vCone )
{
    int RetValue0, RetValue1;
    Ivy_Obj_t * pObjR = Ivy_Regular(pObj);
    assert( !Ivy_ObjIsBuf(pObjR) );
    assert( Type != IVY_EXOR || !Ivy_IsComplement(pObj) );

    // make sure the node is not visited twice in different polarities
    if ( Ivy_IsComplement(pObj) )
    { // if complemented, mark B
        if ( pObjR->fMarkA )
            return -1;
        pObjR->fMarkB = 1;
    }
    else
    { // if non-complicated, mark A
        if ( pObjR->fMarkB )
            return -1;
        pObjR->fMarkA = 1;
    }
    Vec_PtrPush( vCone, pObjR );

    // if the node is the end of the tree, return
    if ( Ivy_IsComplement(pObj) || Ivy_ObjType(pObj) != Type )
    {
        if ( Ivy_ObjRefs(pObjR) == 1 )
            return 1;
        assert( Ivy_ObjRefs(pObjR) > 1 );
        Vec_PtrPush( vFront, pObj );
        return 0;
    }

    // branch on the node
    assert( !Ivy_IsComplement(pObj) );
    assert( Ivy_ObjIsNode(pObj) );
    // what if buffer has more than one fanout???
    RetValue0 = Ivy_ManFindAlgCut_rec( Ivy_ObjReal( Ivy_ObjChild0(pObj) ), Type, vFront, vCone );
    RetValue1 = Ivy_ManFindAlgCut_rec( Ivy_ObjReal( Ivy_ObjChild1(pObj) ), Type, vFront, vCone );
    if ( RetValue0 == -1 || RetValue1 == -1 )
        return -1;

    // the case when both have no external references
    if ( RetValue0 && RetValue1 )
    {
        if ( Ivy_ObjRefs(pObj) == 1 )
            return 1;
        assert( Ivy_ObjRefs(pObj) > 1 );
        Vec_PtrPush( vFront, pObj );
        return 0;
    }
    // the case when one of them has external references
    if ( RetValue0 )
        Vec_PtrPush( vFront, Ivy_ObjReal( Ivy_ObjChild0(pObj) ) );
    if ( RetValue1 )
        Vec_PtrPush( vFront, Ivy_ObjReal( Ivy_ObjChild1(pObj) ) );
    return 0;
}

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

  Synopsis    [Computing one algebraic cut.]

  Description [Algebraic cut stops when we hit (a) CI, (b) complemented edge,
  (c) boundary of different gates. Returns 1 if this is a pure tree.
  Returns -1 if the contant 0 is detected. Return 0 if the array can be used.]
               
  SideEffects []

  SeeAlso     []

***********************************************************************/
int Ivy_ManFindAlgCut( Ivy_Obj_t * pRoot, Vec_Ptr_t * vFront, Vec_Ptr_t * vLeaves, Vec_Ptr_t * vCone )
{
    Ivy_Obj_t * pObj, * pPrev;
    int RetValue, i;
    assert( !Ivy_IsComplement(pRoot) );
    assert( Ivy_ObjIsNode(pRoot) );
    // clear the frontier and collect the nodes
    Vec_PtrClear( vCone );
    Vec_PtrClear( vFront );
    Vec_PtrClear( vLeaves );
    RetValue = Ivy_ManFindAlgCut_rec( pRoot, Ivy_ObjType(pRoot), vFront, vCone );
    // clean the marks
    Vec_PtrForEachEntry( Ivy_Obj_t *, vCone, pObj, i )
        pObj->fMarkA = pObj->fMarkB = 0;
    // quit if the same node is found in both polarities
    if ( RetValue == -1 )
        return -1;
    // return if the node is the root of a tree
    if ( RetValue == 1 )
        return 1;
    // return if the cut is composed of two nodes
    if ( Vec_PtrSize(vFront) <= 2 )
        return 1;
    // sort the entries in increasing order
    Vec_PtrSort( vFront, (int (*)(void))Ivy_ManFindAlgCutCompare );
    // remove duplicates from vFront and save the nodes in vLeaves
    pPrev = Vec_PtrEntry(vFront, 0);
    Vec_PtrPush( vLeaves, pPrev );
    Vec_PtrForEachEntryStart( Ivy_Obj_t *, vFront, pObj, i, 1 )
    {
        // compare current entry and the previous entry
        if ( pObj == pPrev )
        {
            if ( Ivy_ObjIsExor(pRoot) ) // A <+> A = 0
            {
                // vLeaves are no longer structural support of pRoot!!!
                Vec_PtrPop(vLeaves);  
                pPrev = Vec_PtrSize(vLeaves) == 0 ? NULL : Vec_PtrEntryLast(vLeaves);
            }
            continue;
        }
        if ( pObj == Ivy_Not(pPrev) )
        {
            assert( Ivy_ObjIsAnd(pRoot) );
            return -1;
        }
        pPrev = pObj;
        Vec_PtrPush( vLeaves, pObj );
    }
    if ( Vec_PtrSize(vLeaves) == 0 )
        return -1;
    if ( Vec_PtrSize(vLeaves) <= 2 )
        return 1;
    return 0;
}


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


ABC_NAMESPACE_IMPL_END