Fixed opt_muxtree performance bug

diff --git a/passes/opt/opt_muxtree.cc b/passes/opt/opt_muxtree.cc
index ae5fe57e5e73f4c3b582cfac79aa50f473529830..94e29eca9e5cadc124b75c193c96eaa5181eac1e 100644 (file)
--- a/passes/opt/opt_muxtree.cc
+++ b/passes/opt/opt_muxtree.cc
@@ -63,6 +63,7 @@ struct OptMuxtreeWorker
        vector<muxinfo_t> mux2info;
        vector<bool> root_muxes;
        vector<bool> root_enable_muxes;
+       pool<int> root_mux_rerun;
 
        OptMuxtreeWorker(RTLIL::Design *design, RTLIL::Module *module) :
                        design(design), module(module), assign_map(module), removed_count(0)
@@ -179,10 +180,19 @@ struct OptMuxtreeWorker
 
                for (int mux_idx = 0; mux_idx < GetSize(root_muxes); mux_idx++)
                        if (root_muxes.at(mux_idx)) {
-                               log("    Root of a mux tree: %s\n", log_id(mux2info[mux_idx].cell));
+                               log("    Root of a mux tree: %s%s\n", log_id(mux2info[mux_idx].cell), root_enable_muxes.at(mux_idx) ? " (pure)" : "");
+                               root_mux_rerun.erase(mux_idx);
                                eval_root_mux(mux_idx);
                        }
 
+               while (!root_mux_rerun.empty()) {
+                       int mux_idx = *root_mux_rerun.begin();
+                       log("    Root of a mux tree: %s (rerun as non-pure)\n", log_id(mux2info[mux_idx].cell));
+                       log_assert(root_enable_muxes.at(mux_idx));
+                       root_mux_rerun.erase(mux_idx);
+                       eval_root_mux(mux_idx);
+               }
+
                log("  Analyzing evaluation results.\n");
 
                for (auto &mi : mux2info)
@@ -281,7 +291,7 @@ struct OptMuxtreeWorker
                vector<bool> visited_muxes;
        };
 
-       void eval_mux_port(knowledge_t &knowledge, int mux_idx, int port_idx, bool do_replace_known, bool do_enable_ports)
+       void eval_mux_port(knowledge_t &knowledge, int mux_idx, int port_idx, bool do_replace_known, bool do_enable_ports, int abort_count)
        {
                muxinfo_t &muxinfo = mux2info[mux_idx];
 
@@ -306,10 +316,17 @@ struct OptMuxtreeWorker
                        parent_muxes.push_back(m);
                }
                for (int m : parent_muxes)
-                       if (root_muxes.at(m))
-                               eval_mux(knowledge, m, false, do_enable_ports);
-                       else
-                               eval_mux(knowledge, m, do_replace_known, do_enable_ports);
+                       if (root_enable_muxes.at(m))
+                               continue;
+                       else if (root_muxes.at(m)) {
+                               if (abort_count == 0) {
+                                       root_mux_rerun.insert(m);
+                                       root_enable_muxes.at(m) = true;
+                                       log("      Removing pure flag from root mux %s.\n", log_id(mux2info[m].cell));
+                               } else
+                                       eval_mux(knowledge, m, false, do_enable_ports, abort_count - 1);
+                       } else
+                               eval_mux(knowledge, m, do_replace_known, do_enable_ports, abort_count);
                for (int m : parent_muxes)
                        knowledge.visited_muxes[m] = false;
 
@@ -371,7 +388,7 @@ struct OptMuxtreeWorker
                }
        }
 
-       void eval_mux(knowledge_t &knowledge, int mux_idx, bool do_replace_known, bool do_enable_ports)
+       void eval_mux(knowledge_t &knowledge, int mux_idx, bool do_replace_known, bool do_enable_ports, int abort_count)
        {
                muxinfo_t &muxinfo = mux2info[mux_idx];
 
@@ -386,7 +403,7 @@ struct OptMuxtreeWorker
                {
                        portinfo_t &portinfo = muxinfo.ports[port_idx];
                        if (portinfo.const_activated) {
-                               eval_mux_port(knowledge, mux_idx, port_idx, do_replace_known, do_enable_ports);
+                               eval_mux_port(knowledge, mux_idx, port_idx, do_replace_known, do_enable_ports, abort_count);
                                return;
                        }
                }
@@ -400,7 +417,7 @@ struct OptMuxtreeWorker
                        if (portinfo.const_deactivated)
                                continue;
                        if (knowledge.known_active.at(portinfo.ctrl_sig)) {
-                               eval_mux_port(knowledge, mux_idx, port_idx, do_replace_known, do_enable_ports);
+                               eval_mux_port(knowledge, mux_idx, port_idx, do_replace_known, do_enable_ports, abort_count);
                                return;
                        }
                }
@@ -415,7 +432,7 @@ struct OptMuxtreeWorker
                        if (port_idx < GetSize(muxinfo.ports)-1)
                                if (knowledge.known_inactive.at(portinfo.ctrl_sig))
                                        continue;
-                       eval_mux_port(knowledge, mux_idx, port_idx, do_replace_known, do_enable_ports);
+                       eval_mux_port(knowledge, mux_idx, port_idx, do_replace_known, do_enable_ports, abort_count);
                }
        }
 
@@ -426,7 +443,7 @@ struct OptMuxtreeWorker
                knowledge.known_active.resize(GetSize(bit2info));
                knowledge.visited_muxes.resize(GetSize(mux2info));
                knowledge.visited_muxes[mux_idx] = true;
-               eval_mux(knowledge, mux_idx, true, root_enable_muxes.at(mux_idx));
+               eval_mux(knowledge, mux_idx, true, root_enable_muxes.at(mux_idx), 3);
        }
 };