//
// Performs the actual cnfization
//
bool Tseitin::cnfize( Enode * formula, map< enodeid_t, Enode * > & cnf_cache )
{
(void)cnf_cache;
assert( formula );
assert( !formula->isAnd( ) );
Enode * arg_def = egraph.valDupMap1( formula );
if ( arg_def != NULL )
{
vector< Enode * > clause;
clause.push_back( arg_def );
#ifdef PRODUCE_PROOF
if ( config.produce_inter > 0 )
return solver.addSMTClause( clause, egraph.getIPartitions( formula ) );
#endif
return solver.addSMTClause( clause );
}
vector< Enode * > unprocessed_enodes; // Stack for unprocessed enodes
unprocessed_enodes.push_back( formula ); // formula needs to be processed
//
// Visit the DAG of the formula from the leaves to the root
//
while( !unprocessed_enodes.empty( ) )
{
Enode * enode = unprocessed_enodes.back( );
//
// Skip if the node has already been processed before
//
if ( egraph.valDupMap1( enode ) != NULL )
{
unprocessed_enodes.pop_back( );
continue;
}
bool unprocessed_children = false;
Enode * arg_list;
for ( arg_list = enode->getCdr( ) ;
arg_list != egraph.enil ;
arg_list = arg_list->getCdr( ) )
{
Enode * arg = arg_list->getCar( );
assert( arg->isTerm( ) );
//
// Push only if it is an unprocessed boolean operator
//
if ( enode->isBooleanOperator( )
&& egraph.valDupMap1( arg ) == NULL )
{
unprocessed_enodes.push_back( arg );
unprocessed_children = true;
}
//
// If it is an atom (either boolean or theory) just
// store it in the cache
//
else if ( arg->isAtom( ) )
{
egraph.storeDupMap1( arg, arg );
}
}
//
// SKip if unprocessed_children
//
if ( unprocessed_children )
continue;
unprocessed_enodes.pop_back( );
Enode * result = NULL;
//
// At this point, every child has been processed
//
//
// Do the actual cnfization, according to the node type
//
char def_name[ 32 ];
if ( enode->isLit( ) )
{
result = enode;
}
else if ( enode->isNot( ) )
{
Enode * arg_def = egraph.valDupMap1( enode->get1st( ) );
assert( arg_def );
result = egraph.mkNot( egraph.cons( arg_def ) ); // Toggle the literal
}
else
{
Enode * arg_def = NULL;
Enode * new_arg_list = egraph.copyEnodeEtypeListWithCache( enode->getCdr( ) );
//
// If the enode is not top-level it needs a definition
//
if ( formula != enode )
{
sprintf( def_name, CNF_STR, formula->getId( ), enode->getId( ) );
egraph.newSymbol( def_name, sstore.mkBool( ) );
arg_def = egraph.mkVar( def_name );
#ifdef PRODUCE_PROOF
if ( config.produce_inter > 0 )
{
// Tag Positive and negative literals
egraph.tagIFormula( arg_def
, egraph.getIPartitions( enode ) );
egraph.tagIFormula( egraph.mkNot( egraph.cons( arg_def ) )
, egraph.getIPartitions( enode ) );
}
#endif
}
#ifdef PRODUCE_PROOF
uint64_t partitions = 0;
if ( config.produce_inter > 0 )
{
partitions = egraph.getIPartitions( enode );
assert( partitions != 0 );
}
#endif
//
// Handle boolean operators
//
if ( enode->isAnd( ) )
cnfizeAnd( new_arg_list, arg_def
#ifdef PRODUCE_PROOF
, partitions
#endif
);
else if ( enode->isOr( ) )
cnfizeOr( new_arg_list, arg_def
#ifdef PRODUCE_PROOF
, partitions
#endif
);
else if ( enode->isIff( ) )
cnfizeIff( new_arg_list, arg_def
#ifdef PRODUCE_PROOF
, partitions
#endif
);
else if ( enode->isXor( ) )
cnfizeXor( new_arg_list, arg_def
#ifdef PRODUCE_PROOF
, partitions
#endif
);
else
{
opensmt_error2( "operator not handled ", enode->getCar( ) );
}
if ( arg_def != NULL )
result = arg_def;
}
assert( egraph.valDupMap1( enode ) == NULL );
egraph.storeDupMap1( enode, result );
}
if ( formula->isNot( ) )
{
// Retrieve definition of argument
Enode * arg_def = egraph.valDupMap1( formula->get1st( ) );
assert( arg_def );
vector< Enode * > clause;
clause.push_back( toggleLit( arg_def ) );
#ifdef PRODUCE_PROOF
if ( config.produce_inter > 0 )
return solver.addSMTClause( clause, egraph.getIPartitions( formula ) );
#endif
return solver.addSMTClause( clause );
}
return true;
}
//
// Rewrite formula with maximum arity for operators
//
Enode * Cnfizer::rewriteMaxArity( Enode * formula, map< enodeid_t, int > & enodeid_to_incoming_edges )
{
assert( formula );
vector< Enode * > unprocessed_enodes; // Stack for unprocessed enodes
unprocessed_enodes.push_back( formula ); // formula needs to be processed
map< enodeid_t, Enode * > cache; // Cache of processed nodes
//
// Visit the DAG of the formula from the leaves to the root
//
while( !unprocessed_enodes.empty( ) )
{
Enode * enode = unprocessed_enodes.back( );
//
// Skip if the node has already been processed before
//
if ( cache.find( enode->getId( ) ) != cache.end( ) )
{
unprocessed_enodes.pop_back( );
continue;
}
bool unprocessed_children = false;
Enode * arg_list;
for ( arg_list = enode->getCdr( ) ;
arg_list != egraph.enil ;
arg_list = arg_list->getCdr( ) )
{
Enode * arg = arg_list->getCar( );
assert( arg->isTerm( ) );
//
// Push only if it is an unprocessed boolean operator
//
if ( arg->isBooleanOperator( )
&& cache.find( arg->getId( ) ) == cache.end( ) )
{
unprocessed_enodes.push_back( arg );
unprocessed_children = true;
}
//
// If it is an atom (either boolean or theory) just
// store it in the cache
//
else if ( arg->isAtom( ) )
{
cache.insert( make_pair( arg->getId( ), arg ) );
}
}
//
// SKip if unprocessed_children
//
if ( unprocessed_children )
continue;
unprocessed_enodes.pop_back( );
Enode * result = NULL;
//
// At this point, every child has been processed
//
assert ( enode->isBooleanOperator( ) );
if ( enode->isAnd( )
|| enode->isOr ( ) )
{
assert( enode->isAnd( ) || enode->isOr( ) );
//
// Construct the new lists for the operators
//
result = mergeEnodeArgs( enode, cache, enodeid_to_incoming_edges );
}
else
{
result = enode;
}
assert( result );
assert( cache.find( enode->getId( ) ) == cache.end( ) );
cache[ enode->getId( ) ] = result;
}
Enode * top_enode = cache[ formula->getId( ) ];
return top_enode;
}