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Added appending FFs to other existing LUT cluster types (carry, widefn)

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Signed-off-by: Maciej Kurc <mkurc@antmicro.com>
This commit is contained in:
Maciej Kurc 2021-11-19 12:09:55 +01:00
parent 086bcf0615
commit 5bc97c94ae
1 changed files with 67 additions and 18 deletions
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69
nexus/pack.cc
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@ -2310,6 +2310,7 @@ struct NexusPacker
size_t num_comb = 0; size_t num_comb = 0;
size_t num_ff = 0; size_t num_ff = 0;
size_t num_pair = 0; size_t num_pair = 0;
size_t num_glue = 0;
for (auto &cell : ctx->cells) { for (auto &cell : ctx->cells) {
CellInfo *ff = cell.second.get(); CellInfo *ff = cell.second.get();
@ -2320,34 +2321,48 @@ struct NexusPacker
num_ff++; num_ff++;
// Get input net // Get input net
NetInfo *di = get_net_or_empty(ff, id_M); // At the packing stage all inputs go to M // At the packing stage all inputs go to M
NetInfo *di = get_net_or_empty(ff, id_M);
if (di == nullptr || di->driver.cell == nullptr) { if (di == nullptr || di->driver.cell == nullptr) {
continue; continue;
} }
// Skip if there are multiple sinks // Skip if there are multiple sinks on that net
if (di->users.size() != 1) { if (di->users.size() != 1) {
continue; continue;
} }
// Check if the driver is a LUT and the direct connection is from F // Check if the driver is a LUT and the direct connection is from F
CellInfo* lut = di->driver.cell; CellInfo* lut = di->driver.cell;
if (lut->type != id_OXIDE_COMB || di->driver.port != id_F) { if (lut->type != id_OXIDE_COMB) {
continue;
}
if (di->driver.port != id_F &&
di->driver.port != id_F1 &&
di->driver.port != id_OFX)
{
continue; continue;
} }
// The LUT must be in LOGIC mode // The FF must not use M and DI at the same time
if (str_or_default(lut->params, id_MODE, "LOGIC") != "LOGIC") { if (get_net_or_empty(ff, id_DI)) {
continue; continue;
} }
// Skip clusters // The LUT must be in LOGIC/CARRY mode
// FIXME: In case of carry chain make the LUTFF part of the chain if (str_or_default(lut->params, id_MODE, "LOGIC") != "LOGIC" &&
if (lut->cluster != ClusterId() || ff->cluster != ClusterId()) { str_or_default(lut->params, id_MODE, "LOGIC") != "CCU2") {
continue; continue;
} }
// Make a cluster // The FF cannot be in another cluster
if (ff->cluster != ClusterId()) {
continue;
}
// A free LUT, create a new cluster
if (lut->cluster == ClusterId()) {
lut->cluster = lut->name; lut->cluster = lut->name;
lut->constr_children.push_back(ff); lut->constr_children.push_back(ff);
@ -2359,6 +2374,39 @@ struct NexusPacker
num_pair++; num_pair++;
} }
// Attach the FF to the existing cluster of the LUT
else {
// Find the cluster root
CellInfo* root = nullptr;
if (!lut->constr_children.empty()) {
root = lut;
}
else {
for (auto &it : ctx->cells) {
if (it.second->cluster == lut->cluster && !it.second->constr_children.empty()) {
root = it.second.get();
break;
}
}
}
NPNR_ASSERT(root != nullptr);
// Constrain the FF relative to the LUT
ff->cluster = root->cluster;
ff->constr_x = lut->constr_x;
ff->constr_y = lut->constr_y;
ff->constr_z = lut->constr_z + 2;
ff->constr_abs_z = false;
root->constr_children.push_back(ff);
num_glue++;
}
// Reconnect M to DI
rename_port(ctx, ff, id_M, id_DI);
ff->params[id_SEL] = std::string("DL");
}
// Count OXIDE_COMB, OXIDE_FF are already counted // Count OXIDE_COMB, OXIDE_FF are already counted
for (auto &cell : ctx->cells) { for (auto &cell : ctx->cells) {
@ -2369,8 +2417,9 @@ struct NexusPacker
} }
// Print statistics // Print statistics
log_info(" Created %zu LUT+FF pairs from %zu FFs and %zu LUTs\n", log_info(" Created %zu LUT+FF pairs and extended %zu clusters using total %zu FFs and %zu LUTs\n",
num_pair, num_pair,
num_glue,
num_ff, num_ff,
num_comb num_comb
); );