caiyu/nextpnr
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Improve large DFF chains

Browse Source
This commit is contained in:
Miodrag Milanovic 2024-08-08 08:48:05 +02:00
parent dddf12a42b
commit f1137764cd
1 changed files with 16 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

26
himbaechel/uarch/ng-ultra/pack.cc
View File

@ -385,7 +385,7 @@ void NgUltraPacker::pack_xluts(void)
void NgUltraPacker::pack_multi_dffs(void)
{
log_info("Pack multi DFFs...\n");
std::vector<CellInfo*> dff_chain_start;
std::vector<std::pair<CellInfo*, std::vector<CellInfo*>>> dff_chain_start;
for (auto &cell : ctx->cells) {
CellInfo &ci = *cell.second;
if (!ci.type.in(id_NX_DFF))
@ -394,24 +394,34 @@ void NgUltraPacker::pack_multi_dffs(void)
if (!inp || (inp->driver.cell && inp->driver.cell->type.in(id_NX_DFF))) continue;
int cnt = 0;
CellInfo *dff = &ci;
std::vector<CellInfo*> chain;
CellInfo* start_dff = &ci;
while(1) {
NetInfo *o = dff->getPort(id_O);
if (o->users.entries() != 1) break;
dff = (*o->users.begin()).cell;
if (dff->type == id_NX_DFF && (*o->users.begin()).port == id_I) {
cnt++;
if (cnt==95) { // note that start_dff is also part of chain
dff_chain_start.push_back(make_pair(start_dff, chain));
cnt = 0;
start_dff = dff;
chain.clear();
} else {
chain.push_back(dff);
cnt++;
}
} else break;
}
if (cnt)
dff_chain_start.push_back(&ci);
dff_chain_start.push_back(make_pair(start_dff, chain));
}
int dff_only = 0, lut_and_ff = 0;
for (auto dff : dff_chain_start) {
for (auto ch : dff_chain_start) {
CellInfo *dff = ch.first;
CellInfo *root = create_cell_ptr(id_BEYOND_FE, ctx->id(dff->name.str(ctx) + "$fe"));
root->cluster = root->name;
NetInfo *net = dff->getPort(id_I);
NetInfo *o = dff->getPort(id_O);
if (net && net->driver.cell->type == id_NX_LUT && net->users.entries()==1) {
CellInfo *lut = net->driver.cell;
if (!lut->params.count(id_lut_table))
@ -426,11 +436,7 @@ void NgUltraPacker::pack_multi_dffs(void)
packed_cells.insert(dff->name);
++dff_only;
}
while(1) {
if (o->users.entries() != 1) break;
dff = (*o->users.begin()).cell;
if (!(dff->type == id_NX_DFF && (*o->users.begin()).port == id_I)) break;
o = dff->getPort(id_O);
for(auto dff : ch.second) {
CellInfo *new_cell = create_cell_ptr(id_BEYOND_FE, ctx->id(dff->name.str(ctx) + "$fe"));
dff_to_fe(dff, new_cell, true);
++dff_only;