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fsm_detect: Add a cache to avoid excessive CPU usage for big mux networks.

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Fixes #1634.
This commit is contained in:
Marcin Kościelnicki 2020-01-14 22:48:40 +01:00
parent 61ffd2d199
commit a5d2358a60
1 changed files with 17 additions and 9 deletions
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26
passes/fsm/fsm_detect.cc
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@ -34,13 +34,20 @@ static SigSet<sig2driver_entry_t> sig2driver, sig2user;
static std::set<RTLIL::Cell*> muxtree_cells; static std::set<RTLIL::Cell*> muxtree_cells;
static SigPool sig_at_port; static SigPool sig_at_port;
static bool check_state_mux_tree(RTLIL::SigSpec old_sig, RTLIL::SigSpec sig, pool<Cell*> &recursion_monitor) static bool check_state_mux_tree(RTLIL::SigSpec old_sig, RTLIL::SigSpec sig, pool<Cell*> &recursion_monitor, dict<RTLIL::SigSpec, bool> &mux_tree_cache)
{ {
if (mux_tree_cache.find(sig) != mux_tree_cache.end())
return mux_tree_cache.at(sig);
if (sig.is_fully_const() || old_sig == sig) { if (sig.is_fully_const() || old_sig == sig) {
ret_true:
mux_tree_cache[sig] = true;
return true; return true;
} }
if (sig_at_port.check_any(assign_map(sig))) { if (sig_at_port.check_any(assign_map(sig))) {
ret_false:
mux_tree_cache[sig] = false;
return false; return false;
} }
@ -49,13 +56,13 @@ static bool check_state_mux_tree(RTLIL::SigSpec old_sig, RTLIL::SigSpec sig, poo
for (auto &cellport : cellport_list) for (auto &cellport : cellport_list)
{ {
if ((cellport.first->type != "$mux" && cellport.first->type != "$pmux") || cellport.second != "\\Y") { if ((cellport.first->type != "$mux" && cellport.first->type != "$pmux") || cellport.second != "\\Y") {
return false; goto ret_false;
} }
if (recursion_monitor.count(cellport.first)) { if (recursion_monitor.count(cellport.first)) {
log_warning("logic loop in mux tree at signal %s in module %s.\n", log_warning("logic loop in mux tree at signal %s in module %s.\n",
log_signal(sig), RTLIL::id2cstr(module->name)); log_signal(sig), RTLIL::id2cstr(module->name));
return false; goto ret_false;
} }
recursion_monitor.insert(cellport.first); recursion_monitor.insert(cellport.first);
@ -63,22 +70,22 @@ static bool check_state_mux_tree(RTLIL::SigSpec old_sig, RTLIL::SigSpec sig, poo
RTLIL::SigSpec sig_a = assign_map(cellport.first->getPort("\\A")); RTLIL::SigSpec sig_a = assign_map(cellport.first->getPort("\\A"));
RTLIL::SigSpec sig_b = assign_map(cellport.first->getPort("\\B")); RTLIL::SigSpec sig_b = assign_map(cellport.first->getPort("\\B"));
if (!check_state_mux_tree(old_sig, sig_a, recursion_monitor)) { if (!check_state_mux_tree(old_sig, sig_a, recursion_monitor, mux_tree_cache)) {
recursion_monitor.erase(cellport.first); recursion_monitor.erase(cellport.first);
return false; goto ret_false;
} }
for (int i = 0; i < sig_b.size(); i += sig_a.size()) for (int i = 0; i < sig_b.size(); i += sig_a.size())
if (!check_state_mux_tree(old_sig, sig_b.extract(i, sig_a.size()), recursion_monitor)) { if (!check_state_mux_tree(old_sig, sig_b.extract(i, sig_a.size()), recursion_monitor, mux_tree_cache)) {
recursion_monitor.erase(cellport.first); recursion_monitor.erase(cellport.first);
return false; goto ret_false;
} }
recursion_monitor.erase(cellport.first); recursion_monitor.erase(cellport.first);
muxtree_cells.insert(cellport.first); muxtree_cells.insert(cellport.first);
} }
return true; goto ret_true;
} }
static bool check_state_users(RTLIL::SigSpec sig) static bool check_state_users(RTLIL::SigSpec sig)
@ -143,11 +150,12 @@ static void detect_fsm(RTLIL::Wire *wire)
pool<Cell*> recursion_monitor; pool<Cell*> recursion_monitor;
RTLIL::SigSpec sig_q = assign_map(cellport.first->getPort("\\Q")); RTLIL::SigSpec sig_q = assign_map(cellport.first->getPort("\\Q"));
RTLIL::SigSpec sig_d = assign_map(cellport.first->getPort("\\D")); RTLIL::SigSpec sig_d = assign_map(cellport.first->getPort("\\D"));
dict<RTLIL::SigSpec, bool> mux_tree_cache;
if (sig_q != assign_map(wire)) if (sig_q != assign_map(wire))
continue; continue;
looks_like_state_reg = check_state_mux_tree(sig_q, sig_d, recursion_monitor); looks_like_state_reg = check_state_mux_tree(sig_q, sig_d, recursion_monitor, mux_tree_cache);
looks_like_good_state_reg = check_state_users(sig_q); looks_like_good_state_reg = check_state_users(sig_q);
if (!looks_like_state_reg) if (!looks_like_state_reg)