/**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 ] 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" ABC_NAMESPACE_IMPL_START //////////////////////////////////////////////////////////////////////// /// 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 [] ***********************************************************************/ int Msat_ClauseCreate( Msat_Solver_t * p, Msat_IntVec_t * vLits, int 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; int 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, int 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 [] ***********************************************************************/ int 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; } int Msat_ClauseReadMark( Msat_Clause_t * pC ) { return pC->fMark; } int Msat_ClauseReadNum( Msat_Clause_t * pC ) { return pC->Num; } int Msat_ClauseReadTypeA( Msat_Clause_t * pC ) { return pC->fTypeA; } void Msat_ClauseSetMark( Msat_Clause_t * pC, int fMark ) { pC->fMark = fMark; } void Msat_ClauseSetNum( Msat_Clause_t * pC, int Num ) { pC->Num = Num; } void Msat_ClauseSetTypeA( Msat_Clause_t * pC, int 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 [] ***********************************************************************/ int Msat_ClauseIsLocked( Msat_Solver_t * p, Msat_Clause_t * pC ) { Msat_Clause_t ** pReasons = Msat_SolverReadReasonArray( p ); return (int )(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 [] ***********************************************************************/ int 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 [] ***********************************************************************/ int 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, int 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 /// //////////////////////////////////////////////////////////////////////// ABC_NAMESPACE_IMPL_END