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/**CFile****************************************************************
FileName [msatClause.c]
PackageName [A C version of SAT solver MINISAT, originally developed
in C++ by Niklas Een and Niklas Sorensson, Chalmers University of
Technology, Sweden: http://www.cs.chalmers.se/~een/Satzoo.]
Synopsis [Procedures working with SAT clauses.]
Author [Alan Mishchenko <alanmi@eecs.berkeley.edu>]
Affiliation [UC Berkeley]
Date [Ver. 1.0. Started - January 1, 2004.]
Revision [$Id: msatClause.c,v 1.0 2004/01/01 1:00:00 alanmi Exp $]
***********************************************************************/
#include "msatInt.h"
////////////////////////////////////////////////////////////////////////
/// DECLARATIONS ///
////////////////////////////////////////////////////////////////////////
struct Msat_Clause_t_
{
int Num; // unique number of the clause
unsigned fLearned : 1; // 1 if the clause is learned
unsigned fMark : 1; // used to mark visited clauses during proof recording
unsigned fTypeA : 1; // used to mark clauses belonging to A for interpolant computation
unsigned nSize : 14; // the number of literals in the clause
unsigned nSizeAlloc : 15; // the number of bytes allocated for the clause
Msat_Lit_t pData[0];
};
////////////////////////////////////////////////////////////////////////
/// FUNCTION DEFINITIONS ///
////////////////////////////////////////////////////////////////////////
/**Function*************************************************************
Synopsis [Creates a new clause.]
Description [Returns FALSE if top-level conflict detected (must be handled);
TRUE otherwise. 'pClause_out' may be set to NULL if clause is already
satisfied by the top-level assignment.]
SideEffects []
SeeAlso []
***********************************************************************/
bool Msat_ClauseCreate( Msat_Solver_t * p, Msat_IntVec_t * vLits, bool fLearned, Msat_Clause_t ** pClause_out )
{
int * pAssigns = Msat_SolverReadAssignsArray(p);
Msat_ClauseVec_t ** pvWatched;
Msat_Clause_t * pC;
int * pLits;
int nLits, i, j;
int nBytes;
Msat_Var_t Var;
bool Sign;
*pClause_out = NULL;
nLits = Msat_IntVecReadSize(vLits);
pLits = Msat_IntVecReadArray(vLits);
if ( !fLearned )
{
int * pSeen = Msat_SolverReadSeenArray( p );
int nSeenId;
assert( Msat_SolverReadDecisionLevel(p) == 0 );
// sorting literals makes the code trace-equivalent
// with to the original C++ solver
Msat_IntVecSort( vLits, 0 );
// increment the counter of seen twice
nSeenId = Msat_SolverIncrementSeenId( p );
nSeenId = Msat_SolverIncrementSeenId( p );
// nSeenId - 1 stands for negative
// nSeenId stands for positive
// Remove false literals
// there is a bug here!!!!
// when the same var in opposite polarities is given, it drops one polarity!!!
for ( i = j = 0; i < nLits; i++ ) {
// get the corresponding variable
Var = MSAT_LIT2VAR(pLits[i]);
Sign = MSAT_LITSIGN(pLits[i]); // Sign=0 for positive
// check if we already saw this variable in the this clause
if ( pSeen[Var] >= nSeenId - 1 )
{
if ( (pSeen[Var] != nSeenId) == Sign ) // the same lit
continue;
return 1; // two opposite polarity lits -- don't add the clause
}
// mark the variable as seen
pSeen[Var] = nSeenId - !Sign;
// analize the value of this literal
if ( pAssigns[Var] != MSAT_VAR_UNASSIGNED )
{
if ( pAssigns[Var] == pLits[i] )
return 1; // the clause is always true -- don't add anything
// the literal has no impact - skip it
continue;
}
// otherwise, add this literal to the clause
pLits[j++] = pLits[i];
}
Msat_IntVecShrink( vLits, j );
nLits = j;
/*
// the problem with this code is that performance is very
// sensitive to the ordering of adjacency lits
// the best ordering requires fanins first, next fanouts
// this ordering is more convenient to make from FRAIG
// create the adjacency information
if ( nLits > 2 )
{
Msat_Var_t VarI, VarJ;
Msat_IntVec_t * pAdjI, * pAdjJ;
for ( i = 0; i < nLits; i++ )
{
VarI = MSAT_LIT2VAR(pLits[i]);
pAdjI = (Msat_IntVec_t *)p->vAdjacents->pArray[VarI];
for ( j = i+1; j < nLits; j++ )
{
VarJ = MSAT_LIT2VAR(pLits[j]);
pAdjJ = (Msat_IntVec_t *)p->vAdjacents->pArray[VarJ];
Msat_IntVecPushUniqueOrder( pAdjI, VarJ, 1 );
Msat_IntVecPushUniqueOrder( pAdjJ, VarI, 1 );
}
}
}
*/
}
// 'vLits' is now the (possibly) reduced vector of literals.
if ( nLits == 0 )
return 0;
if ( nLits == 1 )
return Msat_SolverEnqueue( p, pLits[0], NULL );
// Allocate clause:
// nBytes = sizeof(unsigned)*(nLits + 1 + (int)fLearned);
nBytes = sizeof(unsigned)*(nLits + 2 + (int)fLearned);
#ifdef USE_SYSTEM_MEMORY_MANAGEMENT
pC = (Msat_Clause_t *)ABC_ALLOC( char, nBytes );
#else
pC = (Msat_Clause_t *)Msat_MmStepEntryFetch( Msat_SolverReadMem(p), nBytes );
#endif
pC->Num = p->nClauses++;
pC->fTypeA = 0;
pC->fMark = 0;
pC->fLearned = fLearned;
pC->nSize = nLits;
pC->nSizeAlloc = nBytes;
memcpy( pC->pData, pLits, sizeof(int)*nLits );
// For learnt clauses only:
if ( fLearned )
{
int * pLevel = Msat_SolverReadDecisionLevelArray( p );
int iLevelMax, iLevelCur, iLitMax;
// Put the second watch on the literal with highest decision level:
iLitMax = 1;
iLevelMax = pLevel[ MSAT_LIT2VAR(pLits[1]) ];
for ( i = 2; i < nLits; i++ )
{
iLevelCur = pLevel[ MSAT_LIT2VAR(pLits[i]) ];
assert( iLevelCur != -1 );
if ( iLevelMax < iLevelCur )
// this is very strange - shouldn't it be???
// if ( iLevelMax > iLevelCur )
iLevelMax = iLevelCur, iLitMax = i;
}
pC->pData[1] = pLits[iLitMax];
pC->pData[iLitMax] = pLits[1];
// Bumping:
// (newly learnt clauses should be considered active)
Msat_ClauseWriteActivity( pC, 0.0 );
Msat_SolverClaBumpActivity( p, pC );
// if ( nLits < 20 )
for ( i = 0; i < nLits; i++ )
{
Msat_SolverVarBumpActivity( p, pLits[i] );
// Msat_SolverVarBumpActivity( p, pLits[i] );
// p->pFreq[ MSAT_LIT2VAR(pLits[i]) ]++;
}
}
// Store clause:
pvWatched = Msat_SolverReadWatchedArray( p );
Msat_ClauseVecPush( pvWatched[ MSAT_LITNOT(pC->pData[0]) ], pC );
Msat_ClauseVecPush( pvWatched[ MSAT_LITNOT(pC->pData[1]) ], pC );
*pClause_out = pC;
return 1;
}
/**Function*************************************************************
Synopsis [Deallocates the clause.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Msat_ClauseFree( Msat_Solver_t * p, Msat_Clause_t * pC, bool fRemoveWatched )
{
if ( fRemoveWatched )
{
Msat_Lit_t Lit;
Msat_ClauseVec_t ** pvWatched;
pvWatched = Msat_SolverReadWatchedArray( p );
Lit = MSAT_LITNOT( pC->pData[0] );
Msat_ClauseRemoveWatch( pvWatched[Lit], pC );
Lit = MSAT_LITNOT( pC->pData[1] );
Msat_ClauseRemoveWatch( pvWatched[Lit], pC );
}
#ifdef USE_SYSTEM_MEMORY_MANAGEMENT
ABC_FREE( pC );
#else
Msat_MmStepEntryRecycle( Msat_SolverReadMem(p), (char *)pC, pC->nSizeAlloc );
#endif
}
/**Function*************************************************************
Synopsis [Access the data field of the clause.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
bool Msat_ClauseReadLearned( Msat_Clause_t * pC ) { return pC->fLearned; }
int Msat_ClauseReadSize( Msat_Clause_t * pC ) { return pC->nSize; }
int * Msat_ClauseReadLits( Msat_Clause_t * pC ) { return pC->pData; }
bool Msat_ClauseReadMark( Msat_Clause_t * pC ) { return pC->fMark; }
int Msat_ClauseReadNum( Msat_Clause_t * pC ) { return pC->Num; }
bool Msat_ClauseReadTypeA( Msat_Clause_t * pC ) { return pC->fTypeA; }
void Msat_ClauseSetMark( Msat_Clause_t * pC, bool fMark ) { pC->fMark = fMark; }
void Msat_ClauseSetNum( Msat_Clause_t * pC, int Num ) { pC->Num = Num; }
void Msat_ClauseSetTypeA( Msat_Clause_t * pC, bool fTypeA ) { pC->fTypeA = fTypeA; }
/**Function*************************************************************
Synopsis [Checks whether the learned clause is locked.]
Description [The clause may be locked if it is the reason of a
recent conflict. Such clause cannot be removed from the database.]
SideEffects []
SeeAlso []
***********************************************************************/
bool Msat_ClauseIsLocked( Msat_Solver_t * p, Msat_Clause_t * pC )
{
Msat_Clause_t ** pReasons = Msat_SolverReadReasonArray( p );
return (bool)(pReasons[MSAT_LIT2VAR(pC->pData[0])] == pC);
}
/**Function*************************************************************
Synopsis [Reads the activity of the given clause.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
float Msat_ClauseReadActivity( Msat_Clause_t * pC )
{
return *((float *)(pC->pData + pC->nSize));
}
/**Function*************************************************************
Synopsis [Sets the activity of the clause.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Msat_ClauseWriteActivity( Msat_Clause_t * pC, float Num )
{
*((float *)(pC->pData + pC->nSize)) = Num;
}
/**Function*************************************************************
Synopsis [Propages the assignment.]
Description [The literal that has become true (Lit) is given to this
procedure. The array of current variable assignments is given for
efficiency. The output literal (pLit_out) can be the second watched
literal (if TRUE is returned) or the conflict literal (if FALSE is
returned). This messy interface is used to improve performance.
This procedure accounts for ~50% of the runtime of the solver.]
SideEffects []
SeeAlso []
***********************************************************************/
bool Msat_ClausePropagate( Msat_Clause_t * pC, Msat_Lit_t Lit, int * pAssigns, Msat_Lit_t * pLit_out )
{
// make sure the false literal is pC->pData[1]
Msat_Lit_t LitF = MSAT_LITNOT(Lit);
if ( pC->pData[0] == LitF )
pC->pData[0] = pC->pData[1], pC->pData[1] = LitF;
assert( pC->pData[1] == LitF );
// if the 0-th watch is true, clause is already satisfied
if ( pAssigns[MSAT_LIT2VAR(pC->pData[0])] == pC->pData[0] )
return 1;
// look for a new watch
if ( pC->nSize > 2 )
{
int i;
for ( i = 2; i < (int)pC->nSize; i++ )
if ( pAssigns[MSAT_LIT2VAR(pC->pData[i])] != MSAT_LITNOT(pC->pData[i]) )
{
pC->pData[1] = pC->pData[i], pC->pData[i] = LitF;
*pLit_out = MSAT_LITNOT(pC->pData[1]);
return 1;
}
}
// clause is unit under assignment
*pLit_out = pC->pData[0];
return 0;
}
/**Function*************************************************************
Synopsis [Simplifies the clause.]
Description [Assumes everything has been propagated! (esp. watches
in clauses are NOT unsatisfied)]
SideEffects []
SeeAlso []
***********************************************************************/
bool Msat_ClauseSimplify( Msat_Clause_t * pC, int * pAssigns )
{
Msat_Var_t Var;
int i, j;
for ( i = j = 0; i < (int)pC->nSize; i++ )
{
Var = MSAT_LIT2VAR(pC->pData[i]);
if ( pAssigns[Var] == MSAT_VAR_UNASSIGNED )
{
pC->pData[j++] = pC->pData[i];
continue;
}
if ( pAssigns[Var] == pC->pData[i] )
return 1;
// otherwise, the value of the literal is false
// make sure, this literal is not watched
assert( i >= 2 );
}
// if the size has changed, update it and move activity
if ( j < (int)pC->nSize )
{
float Activ = Msat_ClauseReadActivity(pC);
pC->nSize = j;
Msat_ClauseWriteActivity(pC, Activ);
}
return 0;
}
/**Function*************************************************************
Synopsis [Computes reason of conflict in the given clause.]
Description [If the literal is unassigned, finds the reason by
complementing literals in the given cluase (pC). If the literal is
assigned, makes sure that this literal is the first one in the clause
and computes the complement of all other literals in the clause.
Returns the reason in the given array (vLits_out). If the clause is
learned, bumps its activity.]
SideEffects []
SeeAlso []
***********************************************************************/
void Msat_ClauseCalcReason( Msat_Solver_t * p, Msat_Clause_t * pC, Msat_Lit_t Lit, Msat_IntVec_t * vLits_out )
{
int i;
// clear the reason
Msat_IntVecClear( vLits_out );
assert( Lit == MSAT_LIT_UNASSIGNED || Lit == pC->pData[0] );
for ( i = (Lit != MSAT_LIT_UNASSIGNED); i < (int)pC->nSize; i++ )
{
assert( Msat_SolverReadAssignsArray(p)[MSAT_LIT2VAR(pC->pData[i])] == MSAT_LITNOT(pC->pData[i]) );
Msat_IntVecPush( vLits_out, MSAT_LITNOT(pC->pData[i]) );
}
if ( pC->fLearned )
Msat_SolverClaBumpActivity( p, pC );
}
/**Function*************************************************************
Synopsis [Removes the given clause from the watched list.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Msat_ClauseRemoveWatch( Msat_ClauseVec_t * vClauses, Msat_Clause_t * pC )
{
Msat_Clause_t ** pClauses;
int nClauses, i;
nClauses = Msat_ClauseVecReadSize( vClauses );
pClauses = Msat_ClauseVecReadArray( vClauses );
for ( i = 0; pClauses[i] != pC; i++ )
assert( i < nClauses );
for ( ; i < nClauses - 1; i++ )
pClauses[i] = pClauses[i+1];
Msat_ClauseVecPop( vClauses );
}
/**Function*************************************************************
Synopsis [Prints the given clause.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Msat_ClausePrint( Msat_Clause_t * pC )
{
int i;
if ( pC == NULL )
printf( "NULL pointer" );
else
{
if ( pC->fLearned )
printf( "Act = %.4f ", Msat_ClauseReadActivity(pC) );
for ( i = 0; i < (int)pC->nSize; i++ )
printf( " %s%d", ((pC->pData[i]&1)? "-": ""), pC->pData[i]/2 + 1 );
}
printf( "\n" );
}
/**Function*************************************************************
Synopsis [Writes the given clause in a file in DIMACS format.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Msat_ClauseWriteDimacs( FILE * pFile, Msat_Clause_t * pC, bool fIncrement )
{
int i;
for ( i = 0; i < (int)pC->nSize; i++ )
fprintf( pFile, "%s%d ", ((pC->pData[i]&1)? "-": ""), pC->pData[i]/2 + (int)(fIncrement>0) );
if ( fIncrement )
fprintf( pFile, "0" );
fprintf( pFile, "\n" );
}
/**Function*************************************************************
Synopsis [Prints the given clause.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Msat_ClausePrintSymbols( Msat_Clause_t * pC )
{
int i;
if ( pC == NULL )
printf( "NULL pointer" );
else
{
// if ( pC->fLearned )
// printf( "Act = %.4f ", Msat_ClauseReadActivity(pC) );
for ( i = 0; i < (int)pC->nSize; i++ )
printf(" "L_LIT, L_lit(pC->pData[i]));
}
printf( "\n" );
}
////////////////////////////////////////////////////////////////////////
/// END OF FILE ///
////////////////////////////////////////////////////////////////////////
|
