stop check_signal_in_fanout from traversing FFs

diff --git a/passes/equiv/equiv_make.cc b/passes/equiv/equiv_make.cc
index e74dab36f9b8a0a387baaec1b1baf53b7579d7bf..e75482e9fc8ea3e2de3ccc7ddcc5550439b3271b 100644 (file)
--- a/passes/equiv/equiv_make.cc
+++ b/passes/equiv/equiv_make.cc
@@ -42,6 +42,14 @@ struct EquivMakeWorker
 
        dict<SigBit, pool<Cell*>> bit2driven; // map: bit <--> and its driven cells
 
+       CellTypes comb_ct;
+
+       EquivMakeWorker()
+       {
+               comb_ct.setup_internals();
+               comb_ct.setup_stdcells();
+       }
+
        void read_blacklists()
        {
                for (auto fn : blacklists)
@@ -415,9 +423,12 @@ struct EquivMakeWorker
                auto driven_cells = bit2driven.at(source_bit);
                for (auto driven_cell: driven_cells)
                {
-                       if (visited_cells.count(driven_cell) > 0)
+                       bool is_comb = comb_ct.cell_known(cell->type);
+                       if (is_comb)
                                continue;
 
+                       if (visited_cells.count(driven_cell) > 0)
+                               continue;
                        visited_cells.insert(driven_cell);
 
                        for (auto &conn: driven_cell->connections())