diff options
Diffstat (limited to 'passes/fsm/fsm_opt.cc')
| -rw-r--r-- | passes/fsm/fsm_opt.cc | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/passes/fsm/fsm_opt.cc b/passes/fsm/fsm_opt.cc index bcaa89bf0..a0e1885ec 100644 --- a/passes/fsm/fsm_opt.cc +++ b/passes/fsm/fsm_opt.cc @@ -30,6 +30,48 @@ struct FsmOpt FsmData fsm_data; RTLIL::Cell *cell; RTLIL::Module *module; + + void opt_unreachable_states() + { + while (1) + { + std::set<int> unreachable_states; + std::vector<FsmData::transition_t> new_transition_table; + std::vector<RTLIL::Const> new_state_table; + std::map<int, int> old_to_new_state; + + for (int i = 0; i < SIZE(fsm_data.state_table); i++) + if (i != fsm_data.reset_state) + unreachable_states.insert(i); + + for (auto &trans : fsm_data.transition_table) + unreachable_states.erase(trans.state_out); + + if (unreachable_states.empty()) + break; + + for (int i = 0; i < SIZE(fsm_data.state_table); i++) { + if (unreachable_states.count(i)) { + log(" Removing unreachable state %s.\n", log_signal(fsm_data.state_table[i])); + continue; + } + old_to_new_state[i] = SIZE(new_state_table); + new_state_table.push_back(fsm_data.state_table[i]); + } + + for (auto trans : fsm_data.transition_table) { + if (unreachable_states.count(trans.state_in)) + continue; + trans.state_in = old_to_new_state.at(trans.state_in); + trans.state_out = old_to_new_state.at(trans.state_out); + new_transition_table.push_back(trans); + } + + new_transition_table.swap(fsm_data.transition_table); + new_state_table.swap(fsm_data.state_table); + fsm_data.reset_state = old_to_new_state.at(fsm_data.reset_state); + } + } bool signal_is_unused(RTLIL::SigSpec sig) { @@ -253,6 +295,8 @@ struct FsmOpt this->cell = cell; this->module = module; + opt_unreachable_states(); + opt_unused_outputs(); opt_alias_inputs(); |