Improve unused-detection for opt_clean driver-driver conflict warning

Signed-off-by: Clifford Wolf <clifford@clifford.at>

diff --git a/passes/opt/opt_clean.cc b/passes/opt/opt_clean.cc
index 2426802903023daee4cf122457f0ead13ccedfc6..f287fdcff270490b9fc45e09d9c473be05d72190 100644 (file)
--- a/passes/opt/opt_clean.cc
+++ b/passes/opt/opt_clean.cc
@@ -97,21 +97,19 @@ void rmunused_module_cells(Module *module, bool verbose)
        for (auto &it : module->cells_) {
                Cell *cell = it.second;
                for (auto &it2 : cell->connections()) {
-                       if (!ct_all.cell_known(cell->type) || ct_all.cell_output(cell->type, it2.first))
-                               for (auto raw_bit : it2.second) {
-                                       if (raw_bit.wire == nullptr)
-                                               continue;
-                                       auto bit = sigmap(raw_bit);
-                                       if (bit.wire == nullptr)
-                                               driver_driver_logs[raw_bit].push_back(stringf("Driver-driver conflict "
-                                                               "for %s between cell %s.%s and constant %s in %s: Resolved using constant.",
-                                                               log_signal(raw_bit), log_id(cell), log_id(it2.first), log_signal(bit), log_id(module)));
-                                       if (bit.wire != nullptr)
-                                               wire2driver[bit].insert(cell);
-                               }
-                       if (!ct_all.cell_known(cell->type) || ct_all.cell_input(cell->type, it2.first))
-                               for (auto raw_bit : it2.second)
-                                       used_raw_bits.insert(raw_bit);
+                       if (ct_all.cell_known(cell->type) && !ct_all.cell_output(cell->type, it2.first))
+                               continue;
+                       for (auto raw_bit : it2.second) {
+                               if (raw_bit.wire == nullptr)
+                                       continue;
+                               auto bit = sigmap(raw_bit);
+                               if (bit.wire == nullptr)
+                                       driver_driver_logs[raw_bit].push_back(stringf("Driver-driver conflict "
+                                                       "for %s between cell %s.%s and constant %s in %s: Resolved using constant.",
+                                                       log_signal(raw_bit), log_id(cell), log_id(it2.first), log_signal(bit), log_id(module)));
+                               if (bit.wire != nullptr)
+                                       wire2driver[bit].insert(cell);
+                       }
                }
                if (keep_cache.query(cell))
                        queue.insert(cell);
@@ -130,12 +128,6 @@ void rmunused_module_cells(Module *module, bool verbose)
                }
        }
 
-       for (auto it : driver_driver_logs) {
-               if (used_raw_bits.count(it.first))
-                       for (auto msg : it.second)
-                               log_warning("%s\n", msg.c_str());
-       }
-
        while (!queue.empty())
        {
                pool<SigBit> bits;
@@ -161,6 +153,22 @@ void rmunused_module_cells(Module *module, bool verbose)
                module->remove(cell);
                count_rm_cells++;
        }
+
+       for (auto &it : module->cells_) {
+               Cell *cell = it.second;
+               for (auto &it2 : cell->connections()) {
+                       if (ct_all.cell_known(cell->type) && !ct_all.cell_input(cell->type, it2.first))
+                               continue;
+                       for (auto raw_bit : it2.second)
+                               used_raw_bits.insert(raw_bit);
+               }
+       }
+
+       for (auto it : driver_driver_logs) {
+               if (used_raw_bits.count(it.first))
+                       for (auto msg : it.second)
+                               log_warning("%s\n", msg.c_str());
+       }
 }
 
 int count_nontrivial_wire_attrs(RTLIL::Wire *w)