Silently resolve completely unused cell-vs-const driver-driver conflicts

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

diff --git a/passes/opt/opt_clean.cc b/passes/opt/opt_clean.cc
index 5d95c4f1afd69bbb4e78f1a1ec920084273b0dba..2426802903023daee4cf122457f0ead13ccedfc6 100644 (file)
--- a/passes/opt/opt_clean.cc
+++ b/passes/opt/opt_clean.cc
@@ -85,7 +85,14 @@ void rmunused_module_cells(Module *module, bool verbose)
 {
        SigMap sigmap(module);
        pool<Cell*> queue, unused;
+       pool<SigBit> used_raw_bits;
        dict<SigBit, pool<Cell*>> wire2driver;
+       dict<SigBit, vector<string>> driver_driver_logs;
+
+       for (auto &it : module->connections_) {
+               for (auto raw_bit : it.second)
+                       used_raw_bits.insert(raw_bit);
+       }
 
        for (auto &it : module->cells_) {
                Cell *cell = it.second;
@@ -96,11 +103,15 @@ void rmunused_module_cells(Module *module, bool verbose)
                                                continue;
                                        auto bit = sigmap(raw_bit);
                                        if (bit.wire == nullptr)
-                                               log_warning("Driver-driver conflict for %s between cell %s.%s and constant %s in %s: Resolved using constant.\n",
-                                                               log_signal(raw_bit), log_id(cell), log_id(it2.first), log_signal(bit), log_id(module));
+                                               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 (keep_cache.query(cell))
                        queue.insert(cell);
@@ -114,9 +125,17 @@ void rmunused_module_cells(Module *module, bool verbose)
                        for (auto bit : sigmap(wire))
                        for (auto c : wire2driver[bit])
                                queue.insert(c), unused.erase(c);
+                       for (auto raw_bit : SigSpec(wire))
+                               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());
+       }
+
        while (!queue.empty())
        {
                pool<SigBit> bits;