luke
/
abc
mirror of https://github.com/YosysHQ/abc.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity
abc/src/base/abci/abcSweep.c

956 lines
30 KiB
C
Raw Blame History

/**CFile****************************************************************
FileName [abcDsd.c]
SystemName [ABC: Logic synthesis and verification system.]
PackageName [Network and node package.]
Synopsis [Technology dependent sweep.]
Author [Alan Mishchenko]
Affiliation [UC Berkeley]
Date [Ver. 1.0. Started - June 20, 2005.]
Revision [$Id: abcDsd.c,v 1.00 2005/06/20 00:00:00 alanmi Exp $]
***********************************************************************/
#include "abc.h"
#include "main.h"
#include "fraig.h"
ABC_NAMESPACE_IMPL_START
////////////////////////////////////////////////////////////////////////
/// DECLARATIONS ///
////////////////////////////////////////////////////////////////////////
static void Abc_NtkFraigSweepUsingExdc( Fraig_Man_t * pMan, Abc_Ntk_t * pNtk );
static stmm_table * Abc_NtkFraigEquiv( Abc_Ntk_t * pNtk, int fUseInv, int fVerbose, int fVeryVerbose );
static void Abc_NtkFraigTransform( Abc_Ntk_t * pNtk, stmm_table * tEquiv, int fUseInv, int fVerbose );
static void Abc_NtkFraigMergeClassMapped( Abc_Ntk_t * pNtk, Abc_Obj_t * pChain, int fUseInv, int fVerbose );
static void Abc_NtkFraigMergeClass( Abc_Ntk_t * pNtk, Abc_Obj_t * pChain, int fUseInv, int fVerbose );
static int Abc_NodeDroppingCost( Abc_Obj_t * pNode );
static int Abc_NtkReduceNodes( Abc_Ntk_t * pNtk, Vec_Ptr_t * vNodes );
static void Abc_NodeSweep( Abc_Obj_t * pNode, int fVerbose );
static void Abc_NodeConstantInput( Abc_Obj_t * pNode, Abc_Obj_t * pFanin, int fConst0 );
static void Abc_NodeComplementInput( Abc_Obj_t * pNode, Abc_Obj_t * pFanin );
////////////////////////////////////////////////////////////////////////
/// FUNCTION DEFINITIONS ///
////////////////////////////////////////////////////////////////////////
/**Function*************************************************************
Synopsis [Sweping functionally equivalence nodes.]
Description [Removes gates with equivalent functionality. Works for
both technology-independent and mapped networks. If the flag is set,
allows adding inverters at the gate outputs.]
SideEffects []
SeeAlso []
***********************************************************************/
int Abc_NtkFraigSweep( Abc_Ntk_t * pNtk, int fUseInv, int fExdc, int fVerbose, int fVeryVerbose )
{
Fraig_Params_t Params;
Abc_Ntk_t * pNtkAig;
Fraig_Man_t * pMan;
stmm_table * tEquiv;
Abc_Obj_t * pObj;
int i, fUseTrick;
assert( !Abc_NtkIsStrash(pNtk) );
// save gate assignments
fUseTrick = 0;
if ( Abc_NtkIsMappedLogic(pNtk) )
{
fUseTrick = 1;
Abc_NtkForEachNode( pNtk, pObj, i )
pObj->pNext = (Abc_Obj_t *)pObj->pData;
}
// derive the AIG
pNtkAig = Abc_NtkStrash( pNtk, 0, 1, 0 );
// reconstruct gate assignments
if ( fUseTrick )
{
// extern void * Abc_FrameReadLibGen();
Hop_ManStop( (Hop_Man_t *)pNtk->pManFunc );
pNtk->pManFunc = Abc_FrameReadLibGen();
pNtk->ntkFunc = ABC_FUNC_MAP;
Abc_NtkForEachNode( pNtk, pObj, i )
pObj->pData = pObj->pNext, pObj->pNext = NULL;
}
// perform fraiging of the AIG
Fraig_ParamsSetDefault( &Params );
Params.fInternal = 1;
pMan = (Fraig_Man_t *)Abc_NtkToFraig( pNtkAig, &Params, 0, 0 );
// cannot use EXDC with FRAIG because it can create classes of equivalent FRAIG nodes
// with representative nodes that do not correspond to the nodes with the current network
// update FRAIG using EXDC
if ( fExdc )
{
if ( pNtk->pExdc == NULL )
printf( "Warning: Networks has no EXDC.\n" );
else
Abc_NtkFraigSweepUsingExdc( pMan, pNtk );
}
// assign levels to the nodes of the network
Abc_NtkLevel( pNtk );
// collect the classes of equivalent nets
tEquiv = Abc_NtkFraigEquiv( pNtk, fUseInv, fVerbose, fVeryVerbose );
// transform the network into the equivalent one
Abc_NtkFraigTransform( pNtk, tEquiv, fUseInv, fVerbose );
stmm_free_table( tEquiv );
// free the manager
Fraig_ManFree( pMan );
Abc_NtkDelete( pNtkAig );
// cleanup the dangling nodes
if ( Abc_NtkHasMapping(pNtk) )
Abc_NtkCleanup( pNtk, fVerbose );
else
Abc_NtkSweep( pNtk, fVerbose );
// check
if ( !Abc_NtkCheck( pNtk ) )
{
printf( "Abc_NtkFraigSweep: The network check has failed.\n" );
return 0;
}
return 1;
}
/**Function*************************************************************
Synopsis [Sweep the network using EXDC.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Abc_NtkFraigSweepUsingExdc( Fraig_Man_t * pMan, Abc_Ntk_t * pNtk )
{
Fraig_Node_t * gNodeExdc, * gNode, * gNodeRes;
Abc_Obj_t * pNode, * pNodeAig;
int i;
extern Fraig_Node_t * Abc_NtkToFraigExdc( Fraig_Man_t * pMan, Abc_Ntk_t * pNtk, Abc_Ntk_t * pNtkExdc );
assert( pNtk->pExdc );
// derive FRAIG node representing don't-cares in the EXDC network
gNodeExdc = Abc_NtkToFraigExdc( pMan, pNtk, pNtk->pExdc );
// update the node pointers
Abc_NtkForEachNode( pNtk, pNode, i )
{
// skip the constant input nodes
if ( Abc_ObjFaninNum(pNode) == 0 )
continue;
// get the strashed node
pNodeAig = pNode->pCopy;
// skip the dangling nodes
if ( pNodeAig == NULL )
continue;
// get the FRAIG node
gNode = Fraig_NotCond( Abc_ObjRegular(pNodeAig)->pCopy, (int)Abc_ObjIsComplement(pNodeAig) );
// perform ANDing with EXDC
gNodeRes = Fraig_NodeAnd( pMan, gNode, Fraig_Not(gNodeExdc) );
// write the node back
Abc_ObjRegular(pNodeAig)->pCopy = (Abc_Obj_t *)Fraig_NotCond( gNodeRes, (int)Abc_ObjIsComplement(pNodeAig) );
}
}
/**Function*************************************************************
Synopsis [Collects equivalence classses of node in the network.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
stmm_table * Abc_NtkFraigEquiv( Abc_Ntk_t * pNtk, int fUseInv, int fVerbose, int fVeryVerbose )
{
Abc_Obj_t * pList, * pNode, * pNodeAig;
Fraig_Node_t * gNode;
Abc_Obj_t ** ppSlot;
stmm_table * tStrash2Net;
stmm_table * tResult;
stmm_generator * gen;
int c, Counter;
// create mapping of strashed nodes into the corresponding network nodes
tStrash2Net = stmm_init_table(stmm_ptrcmp,stmm_ptrhash);
Abc_NtkForEachNode( pNtk, pNode, c )
{
// skip the constant input nodes
if ( Abc_ObjFaninNum(pNode) == 0 )
continue;
// get the strashed node
pNodeAig = pNode->pCopy;
// skip the dangling nodes
if ( pNodeAig == NULL )
continue;
// skip the nodes that fanout into COs
if ( Abc_NodeFindCoFanout(pNode) )
continue;
// get the FRAIG node
gNode = Fraig_NotCond( Abc_ObjRegular(pNodeAig)->pCopy, (int)Abc_ObjIsComplement(pNodeAig) );
if ( !stmm_find_or_add( tStrash2Net, (char *)Fraig_Regular(gNode), (char ***)&ppSlot ) )
*ppSlot = NULL;
// add the node to the list
pNode->pNext = *ppSlot;
*ppSlot = pNode;
// mark the node if it is complemented
pNode->fPhase = Fraig_IsComplement(gNode);
}
// print the classes
c = 0;
Counter = 0;
tResult = stmm_init_table(stmm_ptrcmp,stmm_ptrhash);
stmm_foreach_item( tStrash2Net, gen, (char **)&gNode, (char **)&pList )
{
// skip the trival classes
if ( pList == NULL || pList->pNext == NULL )
continue;
// add the non-trival class
stmm_insert( tResult, (char *)pList, NULL );
// count nodes in the non-trival classes
for ( pNode = pList; pNode; pNode = pNode->pNext )
Counter++;
if ( fVeryVerbose )
{
printf( "Class %2d : {", c );
for ( pNode = pList; pNode; pNode = pNode->pNext )
{
pNode->pCopy = NULL;
printf( " %s", Abc_ObjName(pNode) );
printf( "(%c)", pNode->fPhase? '-' : '+' );
printf( "(%d)", pNode->Level );
}
printf( " }\n" );
c++;
}
}
if ( fVerbose || fVeryVerbose )
{
printf( "Sweeping stats for network \"%s\":\n", pNtk->pName );
printf( "Internal nodes = %d. Different functions (up to compl) = %d.\n", Abc_NtkNodeNum(pNtk), stmm_count(tStrash2Net) );
printf( "Non-trivial classes = %d. Nodes in non-trivial classes = %d.\n", stmm_count(tResult), Counter );
}
stmm_free_table( tStrash2Net );
return tResult;
}
/**Function*************************************************************
Synopsis [Transforms the network using the equivalence relation on nodes.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Abc_NtkFraigTransform( Abc_Ntk_t * pNtk, stmm_table * tEquiv, int fUseInv, int fVerbose )
{
stmm_generator * gen;
Abc_Obj_t * pList;
if ( stmm_count(tEquiv) == 0 )
return;
// merge nodes in the classes
if ( Abc_NtkHasMapping( pNtk ) )
{
Abc_NtkDelayTrace( pNtk );
stmm_foreach_item( tEquiv, gen, (char **)&pList, NULL )
Abc_NtkFraigMergeClassMapped( pNtk, pList, fUseInv, fVerbose );
}
else
{
stmm_foreach_item( tEquiv, gen, (char **)&pList, NULL )
Abc_NtkFraigMergeClass( pNtk, pList, fUseInv, fVerbose );
}
}
/**Function*************************************************************
Synopsis [Transforms the list of one-phase equivalent nodes.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Abc_NtkFraigMergeClassMapped( Abc_Ntk_t * pNtk, Abc_Obj_t * pChain, int fUseInv, int fVerbose )
{
Abc_Obj_t * pListDir, * pListInv;
Abc_Obj_t * pNodeMin, * pNode, * pNext;
float Arrival1, Arrival2;
assert( pChain );
assert( pChain->pNext );
// divide the nodes into two parts:
// those that need the invertor and those that don't need
pListDir = pListInv = NULL;
for ( pNode = pChain, pNext = pChain->pNext;
pNode;
pNode = pNext, pNext = pNode? pNode->pNext : NULL )
{
// check to which class the node belongs
if ( pNode->fPhase == 1 )
{
pNode->pNext = pListDir;
pListDir = pNode;
}
else
{
pNode->pNext = pListInv;
pListInv = pNode;
}
}
// find the node with the smallest number of logic levels
pNodeMin = pListDir;
for ( pNode = pListDir; pNode; pNode = pNode->pNext )
{
Arrival1 = Abc_NodeReadArrival(pNodeMin)->Worst;
Arrival2 = Abc_NodeReadArrival(pNode )->Worst;
// assert( Abc_ObjIsCi(pNodeMin) || Arrival1 > 0 );
// assert( Abc_ObjIsCi(pNode) || Arrival2 > 0 );
if ( Arrival1 > Arrival2 ||
(Arrival1 == Arrival2 && pNodeMin->Level > pNode->Level) ||
(Arrival1 == Arrival2 && pNodeMin->Level == pNode->Level &&
Abc_NodeDroppingCost(pNodeMin) < Abc_NodeDroppingCost(pNode)) )
pNodeMin = pNode;
}
// move the fanouts of the direct nodes
for ( pNode = pListDir; pNode; pNode = pNode->pNext )
if ( pNode != pNodeMin )
Abc_ObjTransferFanout( pNode, pNodeMin );
// find the node with the smallest number of logic levels
pNodeMin = pListInv;
for ( pNode = pListInv; pNode; pNode = pNode->pNext )
{
Arrival1 = Abc_NodeReadArrival(pNodeMin)->Worst;
Arrival2 = Abc_NodeReadArrival(pNode )->Worst;
// assert( Abc_ObjIsCi(pNodeMin) || Arrival1 > 0 );
// assert( Abc_ObjIsCi(pNode) || Arrival2 > 0 );
if ( Arrival1 > Arrival2 ||
(Arrival1 == Arrival2 && pNodeMin->Level > pNode->Level) ||
(Arrival1 == Arrival2 && pNodeMin->Level == pNode->Level &&
Abc_NodeDroppingCost(pNodeMin) < Abc_NodeDroppingCost(pNode)) )
pNodeMin = pNode;
}
// move the fanouts of the direct nodes
for ( pNode = pListInv; pNode; pNode = pNode->pNext )
if ( pNode != pNodeMin )
Abc_ObjTransferFanout( pNode, pNodeMin );
}
/**Function*************************************************************
Synopsis [Process one equivalence class of nodes.]
Description [This function does not remove the nodes. It only switches
around the connections.]
SideEffects []
SeeAlso []
***********************************************************************/
void Abc_NtkFraigMergeClass( Abc_Ntk_t * pNtk, Abc_Obj_t * pChain, int fUseInv, int fVerbose )
{
Abc_Obj_t * pListDir, * pListInv;
Abc_Obj_t * pNodeMin, * pNodeMinInv;
Abc_Obj_t * pNode, * pNext;
assert( pChain );
assert( pChain->pNext );
// find the node with the smallest number of logic levels
pNodeMin = pChain;
for ( pNode = pChain->pNext; pNode; pNode = pNode->pNext )
if ( pNodeMin->Level > pNode->Level ||
( pNodeMin->Level == pNode->Level &&
Abc_NodeDroppingCost(pNodeMin) < Abc_NodeDroppingCost(pNode) ) )
pNodeMin = pNode;
// divide the nodes into two parts:
// those that need the invertor and those that don't need
pListDir = pListInv = NULL;
for ( pNode = pChain, pNext = pChain->pNext;
pNode;
pNode = pNext, pNext = pNode? pNode->pNext : NULL )
{
if ( pNode == pNodeMin )
continue;
// check to which class the node belongs
if ( pNodeMin->fPhase == pNode->fPhase )
{
pNode->pNext = pListDir;
pListDir = pNode;
}
else
{
pNode->pNext = pListInv;
pListInv = pNode;
}
}
// move the fanouts of the direct nodes
for ( pNode = pListDir; pNode; pNode = pNode->pNext )
Abc_ObjTransferFanout( pNode, pNodeMin );
// skip if there are no inverted nodes
if ( pListInv == NULL )
return;
// add the invertor
pNodeMinInv = Abc_NtkCreateNodeInv( pNtk, pNodeMin );
// move the fanouts of the inverted nodes
for ( pNode = pListInv; pNode; pNode = pNode->pNext )
Abc_ObjTransferFanout( pNode, pNodeMinInv );
}
/**Function*************************************************************
Synopsis [Returns the number of literals saved if this node becomes useless.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
int Abc_NodeDroppingCost( Abc_Obj_t * pNode )
{
return 1;
}
/**Function*************************************************************
Synopsis [Removes dangling nodes.]
Description [Returns the number of nodes removed.]
SideEffects []
SeeAlso []
***********************************************************************/
int Abc_NtkCleanup( Abc_Ntk_t * pNtk, int fVerbose )
{
Vec_Ptr_t * vNodes;
int Counter;
assert( Abc_NtkIsLogic(pNtk) );
// mark the nodes reachable from the POs
vNodes = Abc_NtkDfs( pNtk, 0 );
Counter = Abc_NtkReduceNodes( pNtk, vNodes );
if ( fVerbose )
printf( "Cleanup removed %d dangling nodes.\n", Counter );
Vec_PtrFree( vNodes );
return Counter;
}
/**Function*************************************************************
Synopsis [Preserves the nodes collected in the array.]
Description [Returns the number of nodes removed.]
SideEffects []
SeeAlso []
***********************************************************************/
int Abc_NtkReduceNodes( Abc_Ntk_t * pNtk, Vec_Ptr_t * vNodes )
{
Abc_Obj_t * pNode;
int i, Counter;
assert( Abc_NtkIsLogic(pNtk) );
// mark the nodes reachable from the POs
Vec_PtrForEachEntry( Abc_Obj_t *, vNodes, pNode, i )
pNode->fMarkA = 1;
// remove the non-marked nodes
Counter = 0;
Abc_NtkForEachNode( pNtk, pNode, i )
if ( pNode->fMarkA == 0 )
{
Abc_NtkDeleteObj( pNode );
Counter++;
}
// unmark the remaining nodes
Vec_PtrForEachEntry( Abc_Obj_t *, vNodes, pNode, i )
pNode->fMarkA = 0;
// check
if ( !Abc_NtkCheck( pNtk ) )
printf( "Abc_NtkCleanup: The network check has failed.\n" );
return Counter;
}
/**Function*************************************************************
Synopsis [Tranditional sweep of the network.]
Description [Propagates constant and single-input node, removes dangling nodes.]
SideEffects []
SeeAlso []
***********************************************************************/
int Abc_NtkSweep( Abc_Ntk_t * pNtk, int fVerbose )
{
Vec_Ptr_t * vNodes;
Abc_Obj_t * pNode, * pFanout, * pDriver;
int i, nNodesOld;
assert( Abc_NtkIsLogic(pNtk) );
// convert network to BDD representation
if ( !Abc_NtkToBdd(pNtk) )
{
fprintf( stdout, "Converting to BDD has failed.\n" );
return 1;
}
// perform cleanup
nNodesOld = Abc_NtkNodeNum(pNtk);
Abc_NtkCleanup( pNtk, 0 );
// prepare nodes for sweeping
Abc_NtkRemoveDupFanins(pNtk);
Abc_NtkMinimumBase(pNtk);
// collect sweepable nodes
vNodes = Vec_PtrAlloc( 100 );
Abc_NtkForEachNode( pNtk, pNode, i )
if ( Abc_ObjFaninNum(pNode) < 2 )
Vec_PtrPush( vNodes, pNode );
// sweep the nodes
while ( Vec_PtrSize(vNodes) > 0 )
{
// get any sweepable node
pNode = (Abc_Obj_t *)Vec_PtrPop(vNodes);
if ( !Abc_ObjIsNode(pNode) )
continue;
// get any non-CO fanout of this node
pFanout = Abc_NodeFindNonCoFanout(pNode);
if ( pFanout == NULL )
continue;
assert( Abc_ObjIsNode(pFanout) );
// transform the function of the fanout
if ( Abc_ObjFaninNum(pNode) == 0 )
Abc_NodeConstantInput( pFanout, pNode, Abc_NodeIsConst0(pNode) );
else
{
assert( Abc_ObjFaninNum(pNode) == 1 );
pDriver = Abc_ObjFanin0(pNode);
if ( Abc_NodeIsInv(pNode) )
Abc_NodeComplementInput( pFanout, pNode );
Abc_ObjPatchFanin( pFanout, pNode, pDriver );
}
Abc_NodeRemoveDupFanins( pFanout );
Abc_NodeMinimumBase( pFanout );
// check if the fanout should be added
if ( Abc_ObjFaninNum(pFanout) < 2 )
Vec_PtrPush( vNodes, pFanout );
// check if the node has other fanouts
if ( Abc_ObjFanoutNum(pNode) > 0 )
Vec_PtrPush( vNodes, pNode );
else
Abc_NtkDeleteObj_rec( pNode, 1 );
}
Vec_PtrFree( vNodes );
// sweep a node into its CO fanout if all of this is true:
// (a) this node is a single-input node
// (b) the driver of the node has only one fanout (this node)
// (c) the driver is a node
Abc_NtkForEachCo( pNtk, pFanout, i )
{
pNode = Abc_ObjFanin0(pFanout);
if ( Abc_ObjFaninNum(pNode) != 1 )
continue;
pDriver = Abc_ObjFanin0(pNode);
if ( !(Abc_ObjFanoutNum(pDriver) == 1 && Abc_ObjIsNode(pDriver)) )
continue;
// trasform this CO
if ( Abc_NodeIsInv(pNode) )
pDriver->pData = Cudd_Not(pDriver->pData);
Abc_ObjPatchFanin( pFanout, pNode, pDriver );
}
// perform cleanup
Abc_NtkCleanup( pNtk, 0 );
// report
if ( fVerbose )
printf( "Sweep removed %d nodes.\n", nNodesOld - Abc_NtkNodeNum(pNtk) );
return nNodesOld - Abc_NtkNodeNum(pNtk);
}
/**Function*************************************************************
Synopsis [Replaces the local function by its cofactor.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Abc_NodeConstantInput( Abc_Obj_t * pNode, Abc_Obj_t * pFanin, int fConst0 )
{
DdManager * dd = (DdManager *)pNode->pNtk->pManFunc;
DdNode * bVar, * bTemp;
int iFanin;
assert( Abc_NtkIsBddLogic(pNode->pNtk) );
if ( (iFanin = Vec_IntFind( &pNode->vFanins, pFanin->Id )) == -1 )
{
printf( "Node %s should be among", Abc_ObjName(pFanin) );
printf( " the fanins of node %s...\n", Abc_ObjName(pNode) );
return;
}
bVar = Cudd_NotCond( Cudd_bddIthVar(dd, iFanin), fConst0 );
pNode->pData = Cudd_Cofactor( dd, bTemp = (DdNode *)pNode->pData, bVar ); Cudd_Ref( (DdNode *)pNode->pData );
Cudd_RecursiveDeref( dd, bTemp );
}
/**Function*************************************************************
Synopsis [Changes the polarity of one fanin.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
void Abc_NodeComplementInput( Abc_Obj_t * pNode, Abc_Obj_t * pFanin )
{
DdManager * dd = (DdManager *)pNode->pNtk->pManFunc;
DdNode * bVar, * bCof0, * bCof1;
int iFanin;
assert( Abc_NtkIsBddLogic(pNode->pNtk) );
if ( (iFanin = Vec_IntFind( &pNode->vFanins, pFanin->Id )) == -1 )
{
printf( "Node %s should be among", Abc_ObjName(pFanin) );
printf( " the fanins of node %s...\n", Abc_ObjName(pNode) );
return;
}
bVar = Cudd_bddIthVar( dd, iFanin );
bCof0 = Cudd_Cofactor( dd, (DdNode *)pNode->pData, Cudd_Not(bVar) ); Cudd_Ref( bCof0 );
bCof1 = Cudd_Cofactor( dd, (DdNode *)pNode->pData, bVar ); Cudd_Ref( bCof1 );
Cudd_RecursiveDeref( dd, (DdNode *)pNode->pData );
pNode->pData = Cudd_bddIte( dd, bVar, bCof0, bCof1 ); Cudd_Ref( (DdNode *)pNode->pData );
Cudd_RecursiveDeref( dd, bCof0 );
Cudd_RecursiveDeref( dd, bCof1 );
}
/**Function*************************************************************
Synopsis [Removes all objects whose trav ID is not current.]
Description []
SideEffects []
SeeAlso []
***********************************************************************/
int Abc_NodeRemoveNonCurrentObjects( Abc_Ntk_t * pNtk )
{
Abc_Obj_t * pObj;
int Counter, i;
int fVerbose = 0;
// report on the nodes to be deleted
if ( fVerbose )
{
printf( "These nodes will be deleted: \n" );
Abc_NtkForEachObj( pNtk, pObj, i )
if ( !Abc_NodeIsTravIdCurrent( pObj ) )
{
printf( " " );
Abc_ObjPrint( stdout, pObj );
}
}
// delete the nodes
Counter = 0;
Abc_NtkForEachObj( pNtk, pObj, i )
if ( !Abc_NodeIsTravIdCurrent( pObj ) )
{
Abc_NtkDeleteObj( pObj );
Counter++;
}
return Counter;
}
/**Function*************************************************************
Synopsis [Check if the fanin of this latch is a constant.]
Description [Returns 0/1 if constant; -1 if not a constant.]
SideEffects []
SeeAlso []
***********************************************************************/
void Abc_NtkSetTravId_rec( Abc_Obj_t * pObj )
{
Abc_NodeSetTravIdCurrent(pObj);
if ( Abc_ObjFaninNum(pObj) == 0 )
return;
assert( Abc_ObjFaninNum(pObj) == 1 );
Abc_NtkSetTravId_rec( Abc_ObjFanin0(pObj) );
}
/**Function*************************************************************
Synopsis [Check if the fanin of this latch is a constant.]
Description [Returns 0/1 if constant; -1 if not a constant.]
SideEffects []
SeeAlso []
***********************************************************************/
int Abc_NtkCheckConstant_rec( Abc_Obj_t * pObj )
{
if ( Abc_ObjFaninNum(pObj) == 0 )
{
if ( !Abc_ObjIsNode(pObj) )
return -1;
if ( Abc_NodeIsConst0(pObj) )
return 0;
if ( Abc_NodeIsConst1(pObj) )
return 1;
assert( 0 );
return -1;
}
if ( Abc_ObjIsLatch(pObj) || Abc_ObjFaninNum(pObj) > 1 )
return -1;
if ( !Abc_ObjIsNode(pObj) || Abc_NodeIsBuf(pObj) )
return Abc_NtkCheckConstant_rec( Abc_ObjFanin0(pObj) );
if ( Abc_NodeIsInv(pObj) )
{
int RetValue = Abc_NtkCheckConstant_rec( Abc_ObjFanin0(pObj) );
if ( RetValue == 0 )
return 1;
if ( RetValue == 1 )
return 0;
return RetValue;
}
assert( 0 );
return -1;
}
/**Function*************************************************************
Synopsis [Removes redundant latches.]
Description [The redundant latches are of two types:
- Latches fed by a constant which matches the init value of the latch.
- Latches fed by a constant which does not match the init value of the latch
can be all replaced by one latch.]
SideEffects []
SeeAlso []
***********************************************************************/
int Abc_NtkLatchSweep( Abc_Ntk_t * pNtk )
{
Abc_Obj_t * pFanin, * pLatch, * pLatchPivot = NULL;
int Counter, RetValue, i;
Counter = 0;
// go through the latches
Abc_NtkForEachLatch( pNtk, pLatch, i )
{
// check if the latch has constant input
RetValue = Abc_NtkCheckConstant_rec( Abc_ObjFanin0(pLatch) );
if ( RetValue == -1 )
continue;
// found a latch with constant fanin
if ( (RetValue == 1 && Abc_LatchIsInit0(pLatch)) ||
(RetValue == 0 && Abc_LatchIsInit1(pLatch)) )
{
// fanin constant differs from the latch init value
if ( pLatchPivot == NULL )
{
pLatchPivot = pLatch;
continue;
}
if ( Abc_LatchInit(pLatch) != Abc_LatchInit(pLatchPivot) ) // add inverter
pFanin = Abc_NtkCreateNodeInv( pNtk, Abc_ObjFanout0(pLatchPivot) );
else
pFanin = Abc_ObjFanout0(pLatchPivot);
}
else
pFanin = Abc_ObjFanin0(Abc_ObjFanin0(pLatch));
// replace latch
Abc_ObjTransferFanout( Abc_ObjFanout0(pLatch), pFanin );
// delete the extra nodes
Abc_NtkDeleteObj_rec( Abc_ObjFanout0(pLatch), 0 );
Counter++;
}
return Counter;
}
/**Function*************************************************************
Synopsis [Replaces autonumnous logic by free inputs.]
Description [Assumes that non-autonomous logic is marked with
the current ID.]
SideEffects []
SeeAlso []
***********************************************************************/
int Abc_NtkReplaceAutonomousLogic( Abc_Ntk_t * pNtk )
{
Abc_Obj_t * pNode, * pFanin;
Vec_Ptr_t * vNodes;
int i, k, Counter;
// collect the nodes that feed into the reachable logic
vNodes = Vec_PtrAlloc( 100 );
Abc_NtkForEachObj( pNtk, pNode, i )
{
// skip non-visited fanins
if ( !Abc_NodeIsTravIdCurrent(pNode) )
continue;
// look for non-visited fanins
Abc_ObjForEachFanin( pNode, pFanin, k )
{
// skip visited fanins
if ( Abc_NodeIsTravIdCurrent(pFanin) )
continue;
// skip constants and latches fed by constants
if ( Abc_NtkCheckConstant_rec(pFanin) != -1 ||
(Abc_ObjIsBo(pFanin) && Abc_NtkCheckConstant_rec(Abc_ObjFanin0(Abc_ObjFanin0(pFanin))) != -1) )
{
Abc_NtkSetTravId_rec( pFanin );
continue;
}
assert( !Abc_ObjIsLatch(pFanin) );
Vec_PtrPush( vNodes, pFanin );
}
}
Vec_PtrUniqify( vNodes, (int (*)(void))Abc_ObjPointerCompare );
// replace these nodes by the PIs
Vec_PtrForEachEntry( Abc_Obj_t *, vNodes, pNode, i )
{
pFanin = Abc_NtkCreatePi(pNtk);
Abc_ObjAssignName( pFanin, Abc_ObjName(pFanin), NULL );
Abc_NodeSetTravIdCurrent( pFanin );
Abc_ObjTransferFanout( pNode, pFanin );
}
Counter = Vec_PtrSize(vNodes);
Vec_PtrFree( vNodes );
return Counter;
}
/**Function*************************************************************
Synopsis [Sequential cleanup.]
Description [Performs three tasks:
- Removes logic that does not feed into POs.
- Removes latches driven by constant values equal to the initial state.
- Replaces the autonomous components by additional PI variables.]
SideEffects []
SeeAlso []
***********************************************************************/
int Abc_NtkCleanupSeq( Abc_Ntk_t * pNtk, int fLatchSweep, int fAutoSweep, int fVerbose )
{
Vec_Ptr_t * vNodes;
int Counter;
assert( Abc_NtkIsLogic(pNtk) );
// mark the nodes reachable from the POs
vNodes = Abc_NtkDfsSeq( pNtk );
Vec_PtrFree( vNodes );
// remove the non-marked nodes
Counter = Abc_NodeRemoveNonCurrentObjects( pNtk );
if ( fVerbose )
printf( "Cleanup removed %4d dangling objects.\n", Counter );
// check if some of the latches can be removed
if ( fLatchSweep )
{
Counter = Abc_NtkLatchSweep( pNtk );
if ( fVerbose )
printf( "Cleanup removed %4d redundant latches.\n", Counter );
}
// detect the autonomous components
if ( fAutoSweep )
{
vNodes = Abc_NtkDfsSeqReverse( pNtk );
Vec_PtrFree( vNodes );
// replace them by PIs
Counter = Abc_NtkReplaceAutonomousLogic( pNtk );
if ( fVerbose )
printf( "Cleanup added %4d additional PIs.\n", Counter );
// remove the non-marked nodes
Counter = Abc_NodeRemoveNonCurrentObjects( pNtk );
if ( fVerbose )
printf( "Cleanup removed %4d autonomous objects.\n", Counter );
}
// check
if ( !Abc_NtkCheck( pNtk ) )
printf( "Abc_NtkCleanupSeq: The network check has failed.\n" );
return 1;
}
////////////////////////////////////////////////////////////////////////
/// END OF FILE ///
////////////////////////////////////////////////////////////////////////
ABC_NAMESPACE_IMPL_END
Reference in New Issue View Git Blame Copy Permalink