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abc/src/opt/fret/fretFlow.c

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/**CFile****************************************************************
FileName [fretFlow.c]
SystemName [ABC: Logic synthesis and verification system.]
PackageName [Flow-based retiming package.]
Synopsis [Max-flow computation.]
Author [Aaron Hurst]
Affiliation [UC Berkeley]
Date [Ver. 1.0. Started - January 1, 2008.]
Revision [$Id: fretFlow.c,v 1.00 2008/01/01 00:00:00 ahurst Exp $]
***********************************************************************/
#include "abc.h"
#include "vec.h"
#include "fretime.h"
////////////////////////////////////////////////////////////////////////
/// DECLARATIONS ///
////////////////////////////////////////////////////////////////////////
static void dfsfast_e_retreat( Abc_Obj_t *pObj );
static void dfsfast_r_retreat( Abc_Obj_t *pObj );
#define FDIST(xn, xe, yn, ye) (FDATA(xn)->xe##_dist == (FDATA(yn)->ye##_dist + 1))
////////////////////////////////////////////////////////////////////////
/// FUNCTION DEFINITIONS ///
////////////////////////////////////////////////////////////////////////
/**Function*************************************************************
Synopsis [Fast DFS.]
Description [Uses sink-distance-histogram heuristic. May not find all
flow paths: this occurs in a small number of cases where
the flow predecessor points to a non-adjacent node and
the distance ordering is perturbed.]
SideEffects []
SeeAlso []
***********************************************************************/
void dfsfast_preorder( Abc_Ntk_t *pNtk ) {
Abc_Obj_t *pObj, *pNext;
Vec_Ptr_t *vTimeIn, *qn = Vec_PtrAlloc(Abc_NtkObjNum(pNtk));
Vec_Int_t *qe = Vec_IntAlloc(Abc_NtkObjNum(pNtk));
int i, j, d = 0, end;
int qpos = 0;
// create reverse timing edges for backward traversal
#if !defined(IGNORE_TIMING)
if (pManMR->maxDelay) {
Abc_NtkForEachObj( pNtk, pObj, i ) {
Vec_PtrForEachEntry( FTIMEEDGES(pObj), pNext, j ) {
vTimeIn = FDATA(pNext)->vNodes;
if (!vTimeIn) {
vTimeIn = FDATA(pNext)->vNodes = Vec_PtrAlloc(2);
}
Vec_PtrPush(vTimeIn, pObj);
}
}
}
#endif
// clear histogram
memset(Vec_IntArray(pManMR->vSinkDistHist), 0, sizeof(int)*Vec_IntSize(pManMR->vSinkDistHist));
// seed queue : latches, PIOs, and blocks
Abc_NtkForEachObj( pNtk, pObj, i )
if (Abc_ObjIsPo(pObj) ||
Abc_ObjIsLatch(pObj) ||
(pManMR->fIsForward && FTEST(pObj, BLOCK_OR_CONS) & pManMR->constraintMask)) {
Vec_PtrPush(qn, pObj);
Vec_IntPush(qe, 'r');
FDATA(pObj)->r_dist = 1;
} else if (Abc_ObjIsPi(pObj) ||
(!pManMR->fIsForward && FTEST(pObj, BLOCK_OR_CONS) & pManMR->constraintMask)) {
Vec_PtrPush(qn, pObj);
Vec_IntPush(qe, 'e');
FDATA(pObj)->e_dist = 1;
}
// until queue is empty...
while(qpos < Vec_PtrSize(qn)) {
pObj = (Abc_Obj_t *)Vec_PtrEntry(qn, qpos);
assert(pObj);
end = Vec_IntEntry(qe, qpos);
qpos++;
if (end == 'r') {
d = FDATA(pObj)->r_dist;
// 1. structural edges
if (pManMR->fIsForward) {
Abc_ObjForEachFanin( pObj, pNext, i )
if (!FDATA(pNext)->e_dist) {
FDATA(pNext)->e_dist = d+1;
Vec_PtrPush(qn, pNext);
Vec_IntPush(qe, 'e');
}
} else
Abc_ObjForEachFanout( pObj, pNext, i )
if (!FDATA(pNext)->e_dist) {
FDATA(pNext)->e_dist = d+1;
Vec_PtrPush(qn, pNext);
Vec_IntPush(qe, 'e');
}
if (d == 1) continue;
// 2. reverse edges (forward retiming only)
if (pManMR->fIsForward) {
Abc_ObjForEachFanout( pObj, pNext, i )
if (!FDATA(pNext)->r_dist && !Abc_ObjIsLatch(pNext)) {
FDATA(pNext)->r_dist = d+1;
Vec_PtrPush(qn, pNext);
Vec_IntPush(qe, 'r');
}
// 3. timimg edges (forward retiming only)
#if !defined(IGNORE_TIMING)
if (pManMR->maxDelay && FDATA(pObj)->vNodes)
Vec_PtrForEachEntry( FDATA(pObj)->vNodes, pNext, i ) {
if (!FDATA(pNext)->r_dist) {
FDATA(pNext)->r_dist = d+1;
Vec_PtrPush(qn, pNext);
Vec_IntPush(qe, 'r');
}
}
#endif
}
} else { // if 'e'
if (Abc_ObjIsLatch(pObj)) continue;
d = FDATA(pObj)->e_dist;
// 1. through node
if (!FDATA(pObj)->r_dist) {
FDATA(pObj)->r_dist = d+1;
Vec_PtrPush(qn, pObj);
Vec_IntPush(qe, 'r');
}
// 2. reverse edges (backward retiming only)
if (!pManMR->fIsForward) {
Abc_ObjForEachFanin( pObj, pNext, i )
if (!FDATA(pNext)->e_dist && !Abc_ObjIsLatch(pNext)) {
FDATA(pNext)->e_dist = d+1;
Vec_PtrPush(qn, pNext);
Vec_IntPush(qe, 'e');
}
// 3. timimg edges (backward retiming only)
#if !defined(IGNORE_TIMING)
if (pManMR->maxDelay && FDATA(pObj)->vNodes)
Vec_PtrForEachEntry( FDATA(pObj)->vNodes, pNext, i ) {
if (!FDATA(pNext)->e_dist) {
FDATA(pNext)->e_dist = d+1;
Vec_PtrPush(qn, pNext);
Vec_IntPush(qe, 'e');
}
}
#endif
}
}
}
// free time edges
#if !defined(IGNORE_TIMING)
if (pManMR->maxDelay) {
Abc_NtkForEachObj( pNtk, pObj, i ) {
vTimeIn = FDATA(pObj)->vNodes;
if (vTimeIn) {
Vec_PtrFree(vTimeIn);
FDATA(pObj)->vNodes = 0;
}
}
}
#endif
Abc_NtkForEachObj( pNtk, pObj, i ) {
Vec_IntAddToEntry(pManMR->vSinkDistHist, FDATA(pObj)->r_dist, 1);
Vec_IntAddToEntry(pManMR->vSinkDistHist, FDATA(pObj)->e_dist, 1);
#ifdef DEBUG_PREORDER
printf("node %d\t: r=%d\te=%d\n", Abc_ObjId(pObj), FDATA(pObj)->r_dist, FDATA(pObj)->e_dist);
#endif
}
// printf("\t\tpre-ordered (max depth=%d)\n", d+1);
// deallocate
Vec_PtrFree( qn );
Vec_IntFree( qe );
}
int dfsfast_e( Abc_Obj_t *pObj, Abc_Obj_t *pPred ) {
int i;
Abc_Obj_t *pNext;
if (pManMR->fSinkDistTerminate) return 0;
// have we reached the sink?
if(FTEST(pObj, BLOCK_OR_CONS) & pManMR->constraintMask ||
Abc_ObjIsPi(pObj)) {
assert(pPred);
assert(!pManMR->fIsForward);
return 1;
}
FSET(pObj, VISITED_E);
#ifdef DEBUG_VISITED
printf("(%de=%d) ", Abc_ObjId(pObj), FDATA(pObj)->e_dist);
#endif
// 1. structural edges
if (pManMR->fIsForward)
Abc_ObjForEachFanout( pObj, pNext, i ) {
if (!FTEST(pNext, VISITED_R) &&
FDIST(pObj, e, pNext, r) &&
dfsfast_r(pNext, pPred)) {
#ifdef DEBUG_PRINT_FLOWS
printf("o");
#endif
goto found;
}
}
else
Abc_ObjForEachFanin( pObj, pNext, i ) {
if (!FTEST(pNext, VISITED_R) &&
FDIST(pObj, e, pNext, r) &&
dfsfast_r(pNext, pPred)) {
#ifdef DEBUG_PRINT_FLOWS
printf("o");
#endif
goto found;
}
}
if (Abc_ObjIsLatch(pObj))
goto not_found;
// 2. reverse edges (backward retiming only)
if (!pManMR->fIsForward) {
Abc_ObjForEachFanout( pObj, pNext, i ) {
if (!FTEST(pNext, VISITED_E) &&
FDIST(pObj, e, pNext, e) &&
dfsfast_e(pNext, pPred)) {
#ifdef DEBUG_PRINT_FLOWS
printf("i");
#endif
goto found;
}
}
// 3. timing edges (backward retiming only)
#if !defined(IGNORE_TIMING)
if (pManMR->maxDelay)
Vec_PtrForEachEntry( FTIMEEDGES(pObj), pNext, i) {
if (!FTEST(pNext, VISITED_E) &&
FDIST(pObj, e, pNext, e) &&
dfsfast_e(pNext, pPred)) {
#ifdef DEBUG_PRINT_FLOWS
printf("o");
#endif
goto found;
}
}
#endif
}
// unwind
if (FTEST(pObj, FLOW) &&
!FTEST(pObj, VISITED_R) &&
FDIST(pObj, e, pObj, r) &&
dfsfast_r(pObj, FGETPRED(pObj))) {
FUNSET(pObj, FLOW);
FSETPRED(pObj, NULL);
#ifdef DEBUG_PRINT_FLOWS
printf("u");
#endif
goto found;
}
not_found:
FUNSET(pObj, VISITED_E);
dfsfast_e_retreat(pObj);
return 0;
found:
#ifdef DEBUG_PRINT_FLOWS
printf("%d ", Abc_ObjId(pObj));
#endif
FUNSET(pObj, VISITED_E);
return 1;
}
int dfsfast_r( Abc_Obj_t *pObj, Abc_Obj_t *pPred ) {
int i;
Abc_Obj_t *pNext, *pOldPred;
if (pManMR->fSinkDistTerminate) return 0;
#ifdef DEBUG_VISITED
printf("(%dr=%d) ", Abc_ObjId(pObj), FDATA(pObj)->r_dist);
#endif
// have we reached the sink?
if (Abc_ObjIsLatch(pObj) ||
(pManMR->fIsForward && Abc_ObjIsPo(pObj)) ||
(pManMR->fIsForward && FTEST(pObj, BLOCK_OR_CONS) & pManMR->constraintMask)) {
assert(pPred);
return 1;
}
FSET(pObj, VISITED_R);
if (FTEST(pObj, FLOW)) {
pOldPred = FGETPRED(pObj);
if (pOldPred &&
!FTEST(pOldPred, VISITED_E) &&
FDIST(pObj, r, pOldPred, e) &&
dfsfast_e(pOldPred, pOldPred)) {
FSETPRED(pObj, pPred);
#ifdef DEBUG_PRINT_FLOWS
printf("fr");
#endif
goto found;
}
} else {
if (!FTEST(pObj, VISITED_E) &&
FDIST(pObj, r, pObj, e) &&
dfsfast_e(pObj, pObj)) {
FSET(pObj, FLOW);
FSETPRED(pObj, pPred);
#ifdef DEBUG_PRINT_FLOWS
printf("f");
#endif
goto found;
}
}
// 2. reverse edges (forward retiming only)
if (pManMR->fIsForward) {
Abc_ObjForEachFanin( pObj, pNext, i ) {
if (!FTEST(pNext, VISITED_R) &&
FDIST(pObj, r, pNext, r) &&
!Abc_ObjIsLatch(pNext) &&
dfsfast_r(pNext, pPred)) {
#ifdef DEBUG_PRINT_FLOWS
printf("i");
#endif
goto found;
}
}
// 3. timing edges (forward retiming only)
#if !defined(IGNORE_TIMING)
if (pManMR->maxDelay)
Vec_PtrForEachEntry( FTIMEEDGES(pObj), pNext, i) {
if (!FTEST(pNext, VISITED_R) &&
FDIST(pObj, r, pNext, r) &&
dfsfast_r(pNext, pPred)) {
#ifdef DEBUG_PRINT_FLOWS
printf("o");
#endif
goto found;
}
}
#endif
}
FUNSET(pObj, VISITED_R);
dfsfast_r_retreat(pObj);
return 0;
found:
#ifdef DEBUG_PRINT_FLOWS
printf("%d ", Abc_ObjId(pObj));
#endif
FUNSET(pObj, VISITED_R);
return 1;
}
void
dfsfast_e_retreat(Abc_Obj_t *pObj) {
Abc_Obj_t *pNext;
int i, *h;
int old_dist = FDATA(pObj)->e_dist;
int adj_dist, min_dist = MAX_DIST;
// 1. structural edges
if (pManMR->fIsForward)
Abc_ObjForEachFanout( pObj, pNext, i ) {
adj_dist = FDATA(pNext)->r_dist;
if (adj_dist) min_dist = MIN(min_dist, adj_dist);
}
else
Abc_ObjForEachFanin( pObj, pNext, i ) {
adj_dist = FDATA(pNext)->r_dist;
if (adj_dist) min_dist = MIN(min_dist, adj_dist);
}
if (Abc_ObjIsLatch(pObj)) goto update;
// 2. through
if (FTEST(pObj, FLOW)) {
adj_dist = FDATA(pObj)->r_dist;
if (adj_dist) min_dist = MIN(min_dist, adj_dist);
}
// 3. reverse edges (backward retiming only)
if (!pManMR->fIsForward) {
Abc_ObjForEachFanout( pObj, pNext, i ) {
adj_dist = FDATA(pNext)->e_dist;
if (adj_dist) min_dist = MIN(min_dist, adj_dist);
}
// 4. timing edges (backward retiming only)
#if !defined(IGNORE_TIMING)
if (pManMR->maxDelay)
Vec_PtrForEachEntry( FTIMEEDGES(pObj), pNext, i) {
adj_dist = FDATA(pNext)->e_dist;
if (adj_dist) min_dist = MIN(min_dist, adj_dist);
}
#endif
}
update:
++min_dist;
if (min_dist >= MAX_DIST) min_dist = 0;
// printf("[%de=%d->%d] ", Abc_ObjId(pObj), old_dist, min_dist+1);
FDATA(pObj)->e_dist = min_dist;
assert(min_dist < Vec_IntSize(pManMR->vSinkDistHist));
h = Vec_IntArray(pManMR->vSinkDistHist);
h[old_dist]--;
h[min_dist]++;
if (!h[old_dist]) {
pManMR->fSinkDistTerminate = 1;
}
}
void
dfsfast_r_retreat(Abc_Obj_t *pObj) {
Abc_Obj_t *pNext;
int i, *h;
int old_dist = FDATA(pObj)->r_dist;
int adj_dist, min_dist = MAX_DIST;
// 1. through or pred
if (FTEST(pObj, FLOW)) {
if (FGETPRED(pObj)) {
adj_dist = FDATA(FGETPRED(pObj))->e_dist;
if (adj_dist) min_dist = MIN(min_dist, adj_dist);
}
} else {
adj_dist = FDATA(pObj)->e_dist;
if (adj_dist) min_dist = MIN(min_dist, adj_dist);
}
// 2. reverse edges (forward retiming only)
if (pManMR->fIsForward) {
Abc_ObjForEachFanin( pObj, pNext, i )
if (!Abc_ObjIsLatch(pNext)) {
adj_dist = FDATA(pNext)->r_dist;
if (adj_dist) min_dist = MIN(min_dist, adj_dist);
}
// 3. timing edges (forward retiming only)
#if !defined(IGNORE_TIMING)
if (pManMR->maxDelay)
Vec_PtrForEachEntry( FTIMEEDGES(pObj), pNext, i) {
adj_dist = FDATA(pNext)->r_dist;
if (adj_dist) min_dist = MIN(min_dist, adj_dist);
}
#endif
}
++min_dist;
if (min_dist >= MAX_DIST) min_dist = 0;
//printf("[%dr=%d->%d] ", Abc_ObjId(pObj), old_dist, min_dist+1);
FDATA(pObj)->r_dist = min_dist;
assert(min_dist < Vec_IntSize(pManMR->vSinkDistHist));
h = Vec_IntArray(pManMR->vSinkDistHist);
h[old_dist]--;
h[min_dist]++;
if (!h[old_dist]) {
pManMR->fSinkDistTerminate = 1;
}
}
/**Function*************************************************************
Synopsis [Plain DFS.]
Description [Does not use sink-distance-histogram heuristic.]
SideEffects []
SeeAlso []
***********************************************************************/
int dfsplain_e( Abc_Obj_t *pObj, Abc_Obj_t *pPred ) {
int i;
Abc_Obj_t *pNext;
if (FTEST(pObj, BLOCK_OR_CONS) & pManMR->constraintMask ||
Abc_ObjIsPi(pObj)) {
assert(pPred);
assert(!pManMR->fIsForward);
return 1;
}
FSET(pObj, VISITED_E);
// printf(" %de\n", Abc_ObjId(pObj));
// 1. structural edges
if (pManMR->fIsForward)
Abc_ObjForEachFanout( pObj, pNext, i ) {
if (!FTEST(pNext, VISITED_R) &&
dfsplain_r(pNext, pPred)) {
#ifdef DEBUG_PRINT_FLOWS
printf("o");
#endif
goto found;
}
}
else
Abc_ObjForEachFanin( pObj, pNext, i ) {
if (!FTEST(pNext, VISITED_R) &&
dfsplain_r(pNext, pPred)) {
#ifdef DEBUG_PRINT_FLOWS
printf("o");
#endif
goto found;
}
}
if (Abc_ObjIsLatch(pObj))
return 0;
// 2. reverse edges (backward retiming only)
if (!pManMR->fIsForward) {
Abc_ObjForEachFanout( pObj, pNext, i ) {
if (!FTEST(pNext, VISITED_E) &&
dfsplain_e(pNext, pPred)) {
#ifdef DEBUG_PRINT_FLOWS
printf("i");
#endif
goto found;
}
}
// 3. timing edges (backward retiming only)
#if !defined(IGNORE_TIMING)
if (pManMR->maxDelay)
Vec_PtrForEachEntry( FTIMEEDGES(pObj), pNext, i) {
if (!FTEST(pNext, VISITED_E) &&
dfsplain_e(pNext, pPred)) {
#ifdef DEBUG_PRINT_FLOWS
printf("o");
#endif
goto found;
}
}
#endif
}
// unwind
if (FTEST(pObj, FLOW) &&
!FTEST(pObj, VISITED_R) &&
dfsplain_r(pObj, FGETPRED(pObj))) {
FUNSET(pObj, FLOW);
FSETPRED(pObj, NULL);
#ifdef DEBUG_PRINT_FLOWS
printf("u");
#endif
goto found;
}
return 0;
found:
#ifdef DEBUG_PRINT_FLOWS
printf("%d ", Abc_ObjId(pObj));
#endif
return 1;
}
int dfsplain_r( Abc_Obj_t *pObj, Abc_Obj_t *pPred ) {
int i;
Abc_Obj_t *pNext, *pOldPred;
// have we reached the sink?
if (Abc_ObjIsLatch(pObj) ||
(pManMR->fIsForward && Abc_ObjIsPo(pObj)) ||
(pManMR->fIsForward && FTEST(pObj, BLOCK_OR_CONS) & pManMR->constraintMask)) {
assert(pPred);
return 1;
}
FSET(pObj, VISITED_R);
// printf(" %dr\n", Abc_ObjId(pObj));
if (FTEST(pObj, FLOW)) {
pOldPred = FGETPRED(pObj);
if (pOldPred &&
!FTEST(pOldPred, VISITED_E) &&
dfsplain_e(pOldPred, pOldPred)) {
FSETPRED(pObj, pPred);
#ifdef DEBUG_PRINT_FLOWS
printf("fr");
#endif
goto found;
}
} else {
if (!FTEST(pObj, VISITED_E) &&
dfsplain_e(pObj, pObj)) {
FSET(pObj, FLOW);
FSETPRED(pObj, pPred);
#ifdef DEBUG_PRINT_FLOWS
printf("f");
#endif
goto found;
}
}
// 2. follow reverse edges
if (pManMR->fIsForward) { // forward retiming only
Abc_ObjForEachFanin( pObj, pNext, i ) {
if (!FTEST(pNext, VISITED_R) &&
!Abc_ObjIsLatch(pNext) &&
dfsplain_r(pNext, pPred)) {
#ifdef DEBUG_PRINT_FLOWS
printf("i");
#endif
goto found;
}
}
// 3. timing edges (forward only)
#if !defined(IGNORE_TIMING)
if (pManMR->maxDelay)
Vec_PtrForEachEntry( FTIMEEDGES(pObj), pNext, i) {
if (!FTEST(pNext, VISITED_R) &&
dfsplain_r(pNext, pPred)) {
#ifdef DEBUG_PRINT_FLOWS
printf("o");
#endif
goto found;
}
}
#endif
}
return 0;
found:
#ifdef DEBUG_PRINT_FLOWS
printf("%d ", Abc_ObjId(pObj));
#endif
return 1;
}
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