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clkbufmap: Add support for inverters in clock path.

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This commit is contained in:
Marcin Kościelnicki 2019-11-24 16:05:45 +01:00 • committed by Marcin Kościelnicki
parent 7562e7304e
commit 6cdea425b8
4 changed files with 69 additions and 6 deletions
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41
passes/techmap/clkbufmap.cc
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@ -115,6 +115,8 @@ struct ClkbufmapPass : public Pass {
// Cell type, port name, bit index.
pool<pair<IdString, pair<IdString, int>>> sink_ports;
pool<pair<IdString, pair<IdString, int>>> buf_ports;
dict<pair<IdString, pair<IdString, int>>, pair<IdString, int>> inv_ports_out;
dict<pair<IdString, pair<IdString, int>>, pair<IdString, int>> inv_ports_in;
// Process submodules before module using them.
std::vector<Module *> modules_sorted;
@ -133,6 +135,14 @@ struct ClkbufmapPass : public Pass {
if (wire->get_bool_attribute("\\clkbuf_sink"))
for (int i = 0; i < GetSize(wire); i++)
sink_ports.insert(make_pair(module->name, make_pair(wire->name, i)));
auto it = wire->attributes.find("\\clkbuf_inv");
if (it != wire->attributes.end()) {
IdString in_name = RTLIL::escape_id(it->second.decode_string());
for (int i = 0; i < GetSize(wire); i++) {
inv_ports_out[make_pair(module->name, make_pair(wire->name, i))] = make_pair(in_name, i);
inv_ports_in[make_pair(module->name, make_pair(in_name, i))] = make_pair(wire->name, i);
}
}
}
continue;
}
@ -157,6 +167,37 @@ struct ClkbufmapPass : public Pass {
if (buf_ports.count(make_pair(cell->type, make_pair(port.first, i))))
buf_wire_bits.insert(sigmap(port.second[i]));
// Third, propagate tags through inverters.
bool retry = true;
while (retry) {
retry = false;
for (auto cell : module->cells())
for (auto port : cell->connections())
for (int i = 0; i < port.second.size(); i++) {
auto it = inv_ports_out.find(make_pair(cell->type, make_pair(port.first, i)));
auto bit = sigmap(port.second[i]);
// If output of an inverter is connected to a sink, mark it as buffered,
// and request a buffer on the inverter's input instead.
if (it != inv_ports_out.end() && !buf_wire_bits.count(bit) && sink_wire_bits.count(bit)) {
buf_wire_bits.insert(bit);
auto other_bit = sigmap(cell->getPort(it->second.first)[it->second.second]);
sink_wire_bits.insert(other_bit);
retry = true;
}
// If input of an inverter is marked as already-buffered,
// mark its output already-buffered as well.
auto it2 = inv_ports_in.find(make_pair(cell->type, make_pair(port.first, i)));
if (it2 != inv_ports_in.end() && buf_wire_bits.count(bit)) {
auto other_bit = sigmap(cell->getPort(it2->second.first)[it2->second.second]);
if (!buf_wire_bits.count(other_bit)) {
buf_wire_bits.insert(other_bit);
retry = true;
}
}
}
};
// Collect all driven bits.
for (auto cell : module->cells())
for (auto port : cell->connections())