opt_lut: use a worklist, and revisit cells affected by elimination.

diff --git a/passes/opt/opt_lut.cc b/passes/opt/opt_lut.cc
index 8c564b0ed1d0b76fcd5455d9e7067448876cfec3..a79a9a2da285369c51e48bc14e21a8def87ca1fe 100644 (file)
--- a/passes/opt/opt_lut.cc
+++ b/passes/opt/opt_lut.cc
@@ -189,7 +189,8 @@ struct OptLutWorker
 
                log("\n");
                log("Eliminating LUTs.\n");
-               for (auto lut : luts)
+               pool<RTLIL::Cell*> worklist = luts;
+               while (worklist.size())
                {
                        if (limit == 0)
                        {
@@ -197,6 +198,7 @@ struct OptLutWorker
                                break;
                        }
 
+                       auto lut = worklist.pop();
                        SigSpec lut_input = sigmap(lut->getPort("\\A"));
                        pool<int> &lut_dlogic_inputs = luts_dlogic_inputs[lut];
 
@@ -262,8 +264,13 @@ struct OptLutWorker
                                else
                                {
                                        SigSpec lut_output = lut->getPort("\\Y");
-                                       module->connect(lut_output, value);
+                                       for (auto &port : index.query_ports(lut_output))
+                                       {
+                                               if (port.cell != lut && luts.count(port.cell))
+                                                       worklist.insert(port.cell);
+                                       }
 
+                                       module->connect(lut_output, value);
                                        module->remove(lut);
                                        luts.erase(lut);
                                        luts_arity.erase(lut);
@@ -280,7 +287,7 @@ struct OptLutWorker
 
                log("\n");
                log("Combining LUTs.\n");
-               pool<RTLIL::Cell*> worklist = luts;
+               worklist = luts;
                while (worklist.size())
                {
                        if (limit == 0)