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/**CFile****************************************************************
FileName [saigAbs.c]
SystemName [ABC: Logic synthesis and verification system.]
PackageName [Sequential AIG package.]
Synopsis [Proof-based abstraction.]
Author [Alan Mishchenko]
Affiliation [UC Berkeley]
Date [Ver. 1.0. Started - June 20, 2005.]
Revision [$Id: saigAbs.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
***********************************************************************/
#include "saig.h"
#include "cnf.h"
#include "satSolver.h"
#include "satStore.h"
////////////////////////////////////////////////////////////////////////
/// DECLARATIONS ///
////////////////////////////////////////////////////////////////////////
static inline Aig_Obj_t * Saig_ObjFrame( Aig_Obj_t ** ppMap, int nFrames, Aig_Obj_t * pObj, int i ) { return ppMap[nFrames*pObj->Id + i]; }
static inline void Saig_ObjSetFrame( Aig_Obj_t ** ppMap, int nFrames, Aig_Obj_t * pObj, int i, Aig_Obj_t * pNode ) { ppMap[nFrames*pObj->Id + i] = pNode; }
////////////////////////////////////////////////////////////////////////
/// FUNCTION DEFINITIONS ///
////////////////////////////////////////////////////////////////////////
/**Function*************************************************************
Synopsis [Create timeframes of the manager for BMC.]
Description [The resulting manager is combinational. The only PO is
the output of the last frame.]
SideEffects []
SeeAlso []
***********************************************************************/
Aig_Man_t * Saig_ManFramesBmcLast( Aig_Man_t * pAig, int nFrames, Aig_Obj_t *** pppMap )
{
Aig_Man_t * pFrames;
Aig_Obj_t ** ppMap;
Aig_Obj_t * pObj, * pObjLi, * pObjLo;
int i, f;
assert( Saig_ManRegNum(pAig) > 0 );
// start the mapping
ppMap = *pppMap = CALLOC( Aig_Obj_t *, Aig_ManObjNumMax(pAig) * nFrames );
// start the manager
pFrames = Aig_ManStart( Aig_ManNodeNum(pAig) * nFrames );
// create variables for register outputs
Saig_ManForEachLo( pAig, pObj, i )
{
pObj->pData = Aig_ManConst0( pFrames );
Saig_ObjSetFrame( ppMap, nFrames, pObj, 0, pObj->pData );
}
// add timeframes
for ( f = 0; f < nFrames; f++ )
{
// map the constant node
Aig_ManConst1(pAig)->pData = Aig_ManConst1( pFrames );
Saig_ObjSetFrame( ppMap, nFrames, Aig_ManConst1(pAig), f, Aig_ManConst1(pAig)->pData );
// create PI nodes for this frame
Saig_ManForEachPi( pAig, pObj, i )
{
pObj->pData = Aig_ObjCreatePi( pFrames );
Saig_ObjSetFrame( ppMap, nFrames, pObj, f, pObj->pData );
}
// add internal nodes of this frame
Aig_ManForEachNode( pAig, pObj, i )
{
pObj->pData = Aig_And( pFrames, Aig_ObjChild0Copy(pObj), Aig_ObjChild1Copy(pObj) );
Saig_ObjSetFrame( ppMap, nFrames, pObj, f, pObj->pData );
}
// create POs for this frame
if ( f == nFrames - 1 )
{
Saig_ManForEachPo( pAig, pObj, i )
{
pObj->pData = Aig_ObjCreatePo( pFrames, Aig_ObjChild0Copy(pObj) );
Saig_ObjSetFrame( ppMap, nFrames, pObj, f, pObj->pData );
}
break;
}
// save register inputs
Saig_ManForEachLi( pAig, pObj, i )
{
pObj->pData = Aig_ObjChild0Copy(pObj);
Saig_ObjSetFrame( ppMap, nFrames, pObj, f, pObj->pData );
}
// transfer to register outputs
Saig_ManForEachLiLo( pAig, pObjLi, pObjLo, i )
{
pObjLo->pData = pObjLi->pData;
Saig_ObjSetFrame( ppMap, nFrames, pObjLo, f, pObjLo->pData );
}
}
Aig_ManCleanup( pFrames );
// remove mapping for the nodes that are no longer there
for ( i = 0; i < Aig_ManObjNumMax(pAig) * nFrames; i++ )
if ( ppMap[i] && Aig_ObjIsNone( Aig_Regular(ppMap[i]) ) )
ppMap[i] = NULL;
return pFrames;
}
/**Function*************************************************************
Synopsis [Finds the set of variables involved in the UNSAT core.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
int * Saig_ManFindUnsatVariables( Cnf_Dat_t * pCnf, int nConfMax, int fVerbose )
{
void * pSatCnf;
Intp_Man_t * pManProof;
sat_solver * pSat;
Vec_Int_t * vCore;
int * pClause1, * pClause2, * pLit, * pVars, iClause, nVars;
int i, RetValue;
// create the SAT solver
pSat = sat_solver_new();
sat_solver_store_alloc( pSat );
sat_solver_setnvars( pSat, pCnf->nVars );
for ( i = 0; i < pCnf->nClauses; i++ )
{
if ( !sat_solver_addclause( pSat, pCnf->pClauses[i], pCnf->pClauses[i+1] ) )
{
printf( "The BMC problem is trivially UNSAT.\n" );
sat_solver_delete( pSat );
return NULL;
}
}
sat_solver_store_mark_roots( pSat );
// solve the problem
RetValue = sat_solver_solve( pSat, NULL, NULL, (sint64)nConfMax, (sint64)0, (sint64)0, (sint64)0 );
if ( RetValue == l_Undef )
{
printf( "Conflict limit is reached.\n" );
sat_solver_delete( pSat );
return NULL;
}
if ( RetValue == l_True )
{
printf( "The BMC problem is SAT.\n" );
sat_solver_delete( pSat );
return NULL;
}
printf( "SAT solver returned UNSAT after %d conflicts.\n", pSat->stats.conflicts );
assert( RetValue == l_False );
pSatCnf = sat_solver_store_release( pSat );
sat_solver_delete( pSat );
// derive the UNSAT core
pManProof = Intp_ManAlloc();
vCore = Intp_ManUnsatCore( pManProof, pSatCnf, fVerbose );
Intp_ManFree( pManProof );
Sto_ManFree( pSatCnf );
// derive the set of variables on which the core depends
// collect the variable numbers
nVars = 0;
pVars = ALLOC( int, pCnf->nVars );
memset( pVars, 0, sizeof(int) * pCnf->nVars );
Vec_IntForEachEntry( vCore, iClause, i )
{
pClause1 = pCnf->pClauses[iClause];
pClause2 = pCnf->pClauses[iClause+1];
for ( pLit = pClause1; pLit < pClause2; pLit++ )
{
if ( pVars[ (*pLit) >> 1 ] == 0 )
nVars++;
pVars[ (*pLit) >> 1 ] = 1;
if ( fVerbose )
printf( "%s%d ", ((*pLit) & 1)? "-" : "+", (*pLit) >> 1 );
}
if ( fVerbose )
printf( "\n" );
}
Vec_IntFree( vCore );
return pVars;
}
/**Function*************************************************************
Synopsis [Labels nodes with the given CNF variable.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Saig_ManMarkIntoPresentVars_rec( Aig_Obj_t * pObj, Cnf_Dat_t * pCnf, int iVar )
{
int iVarThis = pCnf->pVarNums[pObj->Id];
if ( iVarThis >= 0 && iVarThis != iVar )
return;
assert( Aig_ObjIsNode(pObj) );
Saig_ManMarkIntoPresentVars_rec( Aig_ObjFanin0(pObj), pCnf, iVar );
Saig_ManMarkIntoPresentVars_rec( Aig_ObjFanin1(pObj), pCnf, iVar );
pCnf->pVarNums[pObj->Id] = iVar;
}
/**Function*************************************************************
Synopsis [Performs proof-based abstraction using BMC of the given depth.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
Aig_Man_t * Saig_ManProofAbstraction( Aig_Man_t * p, int nFrames, int nConfMax, int fVerbose )
{
Cnf_Dat_t * pCnf;
Vec_Int_t * vFlops;
Aig_Man_t * pFrames, * pResult;
Aig_Obj_t ** ppAigToFrames;
Aig_Obj_t * pObj, * pObjFrame;
int f, i, * pUnsatCoreVars, clk = clock();
assert( Saig_ManPoNum(p) == 1 );
Aig_ManSetPioNumbers( p );
if ( fVerbose )
printf( "Performing proof-based abstraction with %d frames and %d max conflicts.\n", nFrames, nConfMax );
// create the timeframes
pFrames = Saig_ManFramesBmcLast( p, nFrames, &ppAigToFrames );
// convert them into CNF
// pCnf = Cnf_Derive( pFrames, 0 );
pCnf = Cnf_DeriveSimple( pFrames, 0 );
// collect CNF variables involved in UNSAT core
pUnsatCoreVars = Saig_ManFindUnsatVariables( pCnf, nConfMax, 0 );
if ( pUnsatCoreVars == NULL )
{
Aig_ManStop( pFrames );
Cnf_DataFree( pCnf );
return NULL;
}
if ( fVerbose )
{
int Counter = 0;
for ( i = 0; i < pCnf->nVars; i++ )
Counter += pUnsatCoreVars[i];
printf( "The number of variables in the UNSAT core is %d (out of %d).\n", Counter, pCnf->nVars );
}
// map other nodes into existing CNF variables
Aig_ManForEachNode( pFrames, pObj, i )
if ( pCnf->pVarNums[pObj->Id] >= 0 )
Saig_ManMarkIntoPresentVars_rec( pObj, pCnf, pCnf->pVarNums[pObj->Id] );
// collect relevant registers
for ( f = 0; f < nFrames; f++ )
{
Saig_ManForEachLo( p, pObj, i )
{
pObjFrame = Saig_ObjFrame( ppAigToFrames, nFrames, pObj, f );
if ( pObjFrame == NULL )
continue;
pObjFrame = Aig_Regular(pObjFrame);
if ( Aig_ObjIsConst1( pObjFrame ) )
continue;
assert( pCnf->pVarNums[pObjFrame->Id] >= 0 );
if ( pUnsatCoreVars[ pCnf->pVarNums[pObjFrame->Id] ] )
pObj->fMarkA = 1;
}
}
// collect the flops
vFlops = Vec_IntAlloc( 1000 );
Saig_ManForEachLo( p, pObj, i )
if ( pObj->fMarkA )
{
pObj->fMarkA = 0;
Vec_IntPush( vFlops, i );
}
if ( fVerbose )
{
printf( "The number of relevant registers is %d (out of %d).\n", Vec_IntSize(vFlops), Aig_ManRegNum(p) );
PRT( "Time", clock() - clk );
}
// create the resulting AIG
pResult = Saig_ManAbstraction( p, vFlops );
// cleanup
Aig_ManStop( pFrames );
Cnf_DataFree( pCnf );
free( ppAigToFrames );
free( pUnsatCoreVars );
Vec_IntFree( vFlops );
return pResult;
}
////////////////////////////////////////////////////////////////////////
/// END OF FILE ///
////////////////////////////////////////////////////////////////////////
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