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Further improved fsm_detect output, attempt to detect self-resetting circuits

This commit is contained in:
Clifford Wolf 2016-07-09 14:02:49 +02:00
parent d63ffabacb
commit b5a9fba0db
1 changed files with 68 additions and 6 deletions
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74
passes/fsm/fsm_detect.cc
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@ -118,6 +118,7 @@ static void detect_fsm(RTLIL::Wire *wire)
bool has_init_attr = wire->attributes.count("\\init") > 0;
bool is_module_port = sig_at_port.check_any(assign_map(RTLIL::SigSpec(wire)));
bool looks_like_state_reg = false, looks_like_good_state_reg = false;
bool is_self_resetting = false;
if (has_fsm_encoding_none)
return;
@ -142,11 +143,52 @@ static void detect_fsm(RTLIL::Wire *wire)
pool<Cell*> recursion_monitor;
RTLIL::SigSpec sig_q = assign_map(cellport.first->getPort("\\Q"));
RTLIL::SigSpec sig_d = assign_map(cellport.first->getPort("\\D"));
if (sig_q == RTLIL::SigSpec(wire)) {
looks_like_state_reg = check_state_mux_tree(sig_q, sig_d, recursion_monitor);
looks_like_good_state_reg = check_state_users(sig_q);
if (sig_q != assign_map(wire))
continue;
looks_like_state_reg = check_state_mux_tree(sig_q, sig_d, recursion_monitor);
looks_like_good_state_reg = check_state_users(sig_q);
if (!looks_like_state_reg)
break;
ConstEval ce(wire->module);
std::set<sig2driver_entry_t> cellport_list;
sig2user.find(sig_q, cellport_list);
for (auto &cellport : cellport_list)
{
RTLIL::Cell *cell = cellport.first;
bool set_output = false, clr_output = false;
if (cell->type == "$ne")
set_output = true;
if (cell->type == "$eq")
clr_output = true;
if (!set_output && !clr_output) {
clr_output = true;
for (auto &port_it : cell->connections())
if (port_it.first != "\\A" || port_it.first != "\\Y")
clr_output = false;
}
if (set_output || clr_output) {
for (auto &port_it : cell->connections())
if (cell->output(port_it.first)) {
SigSpec sig = assign_map(port_it.second);
Const val(set_output ? State::S1 : State::S0, GetSize(sig));
ce.set(sig, val);
}
}
}
SigSpec sig_y = sig_d, sig_undef;
if (ce.eval(sig_y, sig_undef))
is_self_resetting = true;
}
if (has_fsm_encoding_attr)
@ -165,20 +207,40 @@ static void detect_fsm(RTLIL::Wire *wire)
if (!looks_like_state_reg)
warnings.push_back("Doesn't look like a proper FSM. Possible simulation-synthesis mismatch!\n");
if (is_self_resetting)
warnings.push_back("FSM seems to be self-resetting. Possible simulation-synthesis mismatch!\n");
if (!warnings.empty()) {
string warnmsg = stringf("Regarding the user-specified fsm_encoding attribute on %s.%s:\n", log_id(wire->module), log_id(wire));
for (auto w : warnings) warnmsg += " " + w;
log_warning("%s", warnmsg.c_str());
} else {
log("FSM state register %s in module %s already has fsm_encoding attribute.\n", log_id(wire->module), log_id(wire));
log("FSM state register %s.%s already has fsm_encoding attribute.\n", log_id(wire->module), log_id(wire));
}
}
else
if (looks_like_state_reg && looks_like_good_state_reg && !has_init_attr && !is_module_port)
if (looks_like_state_reg && looks_like_good_state_reg && !has_init_attr && !is_module_port && !is_self_resetting)
{
log("Found FSM state register %s in module %s.\n", wire->name.c_str(), module->name.c_str());
log("Found FSM state register %s.%s.\n", log_id(wire->module), log_id(wire));
wire->attributes["\\fsm_encoding"] = RTLIL::Const("auto");
}
else
if (looks_like_state_reg)
{
log("Not marking %s.%s as FSM state register:\n", log_id(wire->module), log_id(wire));
if (is_module_port)
log(" Register is connected to module port.\n");
if (!looks_like_good_state_reg)
log(" Users of register don't seem to benefit from recoding.\n");
if (has_init_attr)
log(" Register has an initialization value.");
if (is_self_resetting)
log(" Circuit seems to be self-resetting.\n");
}
}
struct FsmDetectPass : public Pass {