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opt_muxtree: optimize for single driver, error on multiple drivers

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This commit is contained in:
Emil J. Tywoniak 2026-06-15 15:04:59 +02:00
parent 8869ce61dc
commit 6032b064e2
1 changed files with 14 additions and 11 deletions
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25
passes/opt/opt_muxtree.cc
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@ -68,7 +68,7 @@ struct OptMuxtreeWorker
// Is bit directly used by non-mux cells or ports?
bool seen_non_mux;
pool<int> mux_users;
pool<int> mux_drivers;
std::optional<int> mux_driver;
};
idict<SigBit> bit2num;
@ -107,7 +107,7 @@ struct OptMuxtreeWorker
// Populate bit2info[]:
// .seen_non_mux
// .mux_users
// .mux_drivers
// .mux_driver
// Populate mux2info[].ports[]:
// .ctrl_sig
// .input_sigs
@ -137,8 +137,11 @@ struct OptMuxtreeWorker
// Analyze port A
muxinfo.ports.push_back(used_port_bit(sig_a, this_mux_idx));
for (int idx : sig2bits(sig_y))
bit2info[idx].mux_drivers.insert(this_mux_idx);
for (int idx : sig2bits(sig_y)) {
if (bit2info[idx].mux_driver)
log_cmd_error("Cell %s Y port signal %s already driven by %s\n", cell->name, log_signal(sig_y), mux2info[*bit2info[idx].mux_driver].cell->name);
bit2info[idx].mux_driver = this_mux_idx;
}
for (int idx : sig2bits(sig_s))
bit2info[idx].seen_non_mux = true;
@ -170,8 +173,8 @@ struct OptMuxtreeWorker
for (int j : bit2info[i].mux_users)
for (auto &p : mux2info[j].ports) {
if (p.input_sigs.count(i))
for (int k : bit2info[i].mux_drivers)
p.input_muxes.insert(k);
if (bit2info[i].mux_driver)
p.input_muxes.insert(*bit2info[i].mux_driver);
}
}
@ -184,14 +187,14 @@ struct OptMuxtreeWorker
root_muxes.resize(GetSize(mux2info));
for (auto &bi : bit2info) {
for (int i : bi.mux_drivers)
if (bi.mux_driver)
for (int j : bi.mux_users)
mux_to_users[i].insert(j);
mux_to_users[*bi.mux_driver].insert(j);
if (!bi.seen_non_mux)
continue;
for (int mux_idx : bi.mux_drivers) {
root_muxes.at(mux_idx) = true;
root_enable_muxes.at(mux_idx) = true;
if (bi.mux_driver) {
root_muxes.at(*bi.mux_driver) = true;
root_enable_muxes.at(*bi.mux_driver) = true;
}
}