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Some improvements in fsm_opt and fsm_map for FSM with unreachable states

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This commit is contained in:
Clifford Wolf 2014-08-09 14:49:51 +02:00
parent 51aa5544fb
commit 2faef89738
3 changed files with 104 additions and 52 deletions
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109
passes/fsm/fsm_map.cc
View file

@ -207,65 +207,72 @@ static void map_fsm(RTLIL::Cell *fsm_cell, RTLIL::Module *module)
// generate next_state signal
RTLIL::Wire *next_state_onehot = module->addWire(NEW_ID, fsm_data.state_table.size());
for (size_t i = 0; i < fsm_data.state_table.size(); i++)
if (SIZE(fsm_data.state_table) == 1)
{
std::map<RTLIL::Const, std::set<int>> pattern_cache;
std::set<int> fullstate_cache;
for (size_t j = 0; j < fsm_data.state_table.size(); j++)
fullstate_cache.insert(j);
for (auto &tr : fsm_data.transition_table) {
if (tr.state_out == int(i))
pattern_cache[tr.ctrl_in].insert(tr.state_in);
else
fullstate_cache.erase(tr.state_in);
}
implement_pattern_cache(module, pattern_cache, fullstate_cache, fsm_data.state_table.size(), state_onehot, ctrl_in, RTLIL::SigSpec(next_state_onehot, i));
}
if (encoding_is_onehot)
{
RTLIL::SigSpec next_state_sig(RTLIL::State::Sm, next_state_wire->width);
for (size_t i = 0; i < fsm_data.state_table.size(); i++) {
RTLIL::Const state = fsm_data.state_table[i];
int bit_idx = -1;
for (size_t j = 0; j < state.bits.size(); j++)
if (state.bits[j] == RTLIL::State::S1)
bit_idx = j;
if (bit_idx >= 0)
next_state_sig.replace(bit_idx, RTLIL::SigSpec(next_state_onehot, i));
}
log_assert(!next_state_sig.has_marked_bits());
module->connect(RTLIL::SigSig(next_state_wire, next_state_sig));
module->connect(next_state_wire, fsm_data.state_table.front());
}
else
{
RTLIL::SigSpec sig_a, sig_b, sig_s;
int reset_state = fsm_data.reset_state;
if (reset_state < 0)
reset_state = 0;
RTLIL::Wire *next_state_onehot = module->addWire(NEW_ID, fsm_data.state_table.size());
for (size_t i = 0; i < fsm_data.state_table.size(); i++) {
RTLIL::Const state = fsm_data.state_table[i];
if (int(i) == fsm_data.reset_state) {
sig_a = RTLIL::SigSpec(state);
} else {
sig_b.append(RTLIL::SigSpec(state));
sig_s.append(RTLIL::SigSpec(next_state_onehot, i));
for (size_t i = 0; i < fsm_data.state_table.size(); i++)
{
std::map<RTLIL::Const, std::set<int>> pattern_cache;
std::set<int> fullstate_cache;
for (size_t j = 0; j < fsm_data.state_table.size(); j++)
fullstate_cache.insert(j);
for (auto &tr : fsm_data.transition_table) {
if (tr.state_out == int(i))
pattern_cache[tr.ctrl_in].insert(tr.state_in);
else
fullstate_cache.erase(tr.state_in);
}
implement_pattern_cache(module, pattern_cache, fullstate_cache, fsm_data.state_table.size(), state_onehot, ctrl_in, RTLIL::SigSpec(next_state_onehot, i));
}
RTLIL::Cell *mux_cell = module->addCell(NEW_ID, "$safe_pmux");
mux_cell->setPort("\\A", sig_a);
mux_cell->setPort("\\B", sig_b);
mux_cell->setPort("\\S", sig_s);
mux_cell->setPort("\\Y", RTLIL::SigSpec(next_state_wire));
mux_cell->parameters["\\WIDTH"] = RTLIL::Const(sig_a.size());
mux_cell->parameters["\\S_WIDTH"] = RTLIL::Const(sig_s.size());
if (encoding_is_onehot)
{
RTLIL::SigSpec next_state_sig(RTLIL::State::Sm, next_state_wire->width);
for (size_t i = 0; i < fsm_data.state_table.size(); i++) {
RTLIL::Const state = fsm_data.state_table[i];
int bit_idx = -1;
for (size_t j = 0; j < state.bits.size(); j++)
if (state.bits[j] == RTLIL::State::S1)
bit_idx = j;
if (bit_idx >= 0)
next_state_sig.replace(bit_idx, RTLIL::SigSpec(next_state_onehot, i));
}
log_assert(!next_state_sig.has_marked_bits());
module->connect(RTLIL::SigSig(next_state_wire, next_state_sig));
}
else
{
RTLIL::SigSpec sig_a, sig_b, sig_s;
int reset_state = fsm_data.reset_state;
if (reset_state < 0)
reset_state = 0;
for (size_t i = 0; i < fsm_data.state_table.size(); i++) {
RTLIL::Const state = fsm_data.state_table[i];
if (int(i) == fsm_data.reset_state) {
sig_a = RTLIL::SigSpec(state);
} else {
sig_b.append(RTLIL::SigSpec(state));
sig_s.append(RTLIL::SigSpec(next_state_onehot, i));
}
}
RTLIL::Cell *mux_cell = module->addCell(NEW_ID, "$safe_pmux");
mux_cell->setPort("\\A", sig_a);
mux_cell->setPort("\\B", sig_b);
mux_cell->setPort("\\S", sig_s);
mux_cell->setPort("\\Y", RTLIL::SigSpec(next_state_wire));
mux_cell->parameters["\\WIDTH"] = RTLIL::Const(sig_a.size());
mux_cell->parameters["\\S_WIDTH"] = RTLIL::Const(sig_s.size());
}
}
// Generate ctrl_out signal

44
passes/fsm/fsm_opt.cc
View file

@ -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();