Various cleanups and improvements in opt_muxtree
authorClifford Wolf <clifford@clifford.at>
Sun, 18 Jan 2015 10:17:56 +0000 (11:17 +0100)
committerClifford Wolf <clifford@clifford.at>
Sun, 18 Jan 2015 10:17:56 +0000 (11:17 +0100)
passes/opt/opt_muxtree.cc

index 33dd12a03fa9b2aeeb0018bc59cdadbd712ca62f..5a88b5a19abf1a4490d13cf03ba3c93df3402623 100644 (file)
@@ -37,39 +37,33 @@ struct OptMuxtreeWorker
        SigMap assign_map;
        int removed_count;
 
-        struct bitDef_t : public std::pair<RTLIL::Wire*, int> {
-               bitDef_t() : std::pair<RTLIL::Wire*, int>(NULL, 0) { }
-               bitDef_t(const RTLIL::SigBit &bit) : std::pair<RTLIL::Wire*, int>(bit.wire, bit.offset) { }
-       };
-
-
        struct bitinfo_t {
                int num;
-               bitDef_t bit;
+               SigBit bit;
                bool seen_non_mux;
-               std::vector<int> mux_users;
-               std::vector<int> mux_drivers;
+               vector<int> mux_users;
+               vector<int> mux_drivers;
        };
 
-       std::map<bitDef_t, int> bit2num;
-       std::vector<bitinfo_t> bit2info;
+       dict<SigBit, int> bit2num;
+       vector<bitinfo_t> bit2info;
 
        struct portinfo_t {
-               std::vector<int> ctrl_sigs;
-               std::vector<int> input_sigs;
-               std::vector<int> input_muxes;
+               int ctrl_sig;
+               vector<int> input_sigs;
+               vector<int> input_muxes;
                bool const_activated;
+               bool const_deactivated;
                bool enabled;
        };
 
        struct muxinfo_t {
                RTLIL::Cell *cell;
-               std::vector<portinfo_t> ports;
+               vector<portinfo_t> ports;
        };
 
-       std::vector<muxinfo_t> mux2info;
-
-       std::set<int> root_muxes;
+       vector<muxinfo_t> mux2info;
+       vector<bool> root_muxes;
 
        OptMuxtreeWorker(RTLIL::Design *design, RTLIL::Module *module) :
                        design(design), module(module), assign_map(module), removed_count(0)
@@ -83,9 +77,10 @@ struct OptMuxtreeWorker
                //      .mux_users
                //      .mux_drivers
                // Populate mux2info[].ports[]:
-               //      .ctrl_sigs
+               //      .ctrl_sig
                //      .input_sigs
                //      .const_activated
+               //      .const_deactivated
                for (auto cell : module->cells())
                {
                        if (cell->type == "$mux" || cell->type == "$pmux")
@@ -102,13 +97,13 @@ struct OptMuxtreeWorker
                                        RTLIL::SigSpec sig = sig_b.extract(i*sig_a.size(), sig_a.size());
                                        RTLIL::SigSpec ctrl_sig = assign_map(sig_s.extract(i, 1));
                                        portinfo_t portinfo;
+                                       portinfo.ctrl_sig = sig2bits(ctrl_sig, false).front();
                                        for (int idx : sig2bits(sig)) {
                                                add_to_list(bit2info[idx].mux_users, mux2info.size());
                                                add_to_list(portinfo.input_sigs, idx);
                                        }
-                                       for (int idx : sig2bits(ctrl_sig))
-                                               add_to_list(portinfo.ctrl_sigs, idx);
                                        portinfo.const_activated = ctrl_sig.is_fully_const() && ctrl_sig.as_bool();
+                                       portinfo.const_deactivated = ctrl_sig.is_fully_const() && !ctrl_sig.as_bool();
                                        portinfo.enabled = false;
                                        muxinfo.ports.push_back(portinfo);
                                }
@@ -118,7 +113,9 @@ struct OptMuxtreeWorker
                                        add_to_list(bit2info[idx].mux_users, mux2info.size());
                                        add_to_list(portinfo.input_sigs, idx);
                                }
+                               portinfo.ctrl_sig = -1;
                                portinfo.const_activated = false;
+                               portinfo.const_deactivated = false;
                                portinfo.enabled = false;
                                muxinfo.ports.push_back(portinfo);
 
@@ -162,6 +159,7 @@ struct OptMuxtreeWorker
                log("  Evaluating internal representation of mux trees.\n");
 
                dict<int, pool<int>> mux_to_users;
+               root_muxes.resize(mux2info.size());
 
                for (auto &bi : bit2info) {
                        for (int i : bi.mux_drivers)
@@ -170,23 +168,24 @@ struct OptMuxtreeWorker
                        if (!bi.seen_non_mux)
                                continue;
                        for (int mux_idx : bi.mux_drivers)
-                               root_muxes.insert(mux_idx);
+                               root_muxes.at(mux_idx) = true;
                }
 
                for (auto &it : mux_to_users)
                        if (GetSize(it.second) > 1)
-                               root_muxes.insert(it.first);
+                               root_muxes.at(it.first) = true;
 
-               for (int mux_idx : root_muxes) {
-                       log("    Root of a mux tree: %s\n", log_id(mux2info[mux_idx].cell));
-                       eval_root_mux(mux_idx);
-               }
+               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));
+                               eval_root_mux(mux_idx);
+                       }
 
                log("  Analyzing evaluation results.\n");
 
                for (auto &mi : mux2info)
                {
-                       std::vector<int> live_ports;
+                       vector<int> live_ports;
                        for (int port_idx = 0; port_idx < GetSize(mi.ports); port_idx++) {
                                portinfo_t &pi = mi.ports[port_idx];
                                if (pi.enabled) {
@@ -247,15 +246,7 @@ struct OptMuxtreeWorker
                }
        }
 
-       bool list_is_subset(const std::vector<int> &sub, const std::vector<int> &super)
-       {
-               for (int v : sub)
-                       if (!is_in_list(super, v))
-                               return false;
-               return true;
-       }
-
-       bool is_in_list(const std::vector<int> &list, int value)
+       bool is_in_list(const vector<int> &list, int value)
        {
                for (int v : list)
                        if (v == value)
@@ -263,15 +254,15 @@ struct OptMuxtreeWorker
                return false;
        }
 
-       void add_to_list(std::vector<int> &list, int value)
+       void add_to_list(vector<int> &list, int value)
        {
                if (!is_in_list(list, value))
                        list.push_back(value);
        }
 
-       std::vector<int> sig2bits(RTLIL::SigSpec sig, bool skip_non_wires = true)
+       vector<int> sig2bits(RTLIL::SigSpec sig, bool skip_non_wires = true)
        {
-               std::vector<int> results;
+               vector<int> results;
                assign_map.apply(sig);
                for (auto &bit : sig)
                        if (bit.wire != NULL) {
@@ -292,57 +283,58 @@ struct OptMuxtreeWorker
        struct knowledge_t
        {
                // database of known inactive signals
-               // the 2nd integer is a reference counter used to manage the
+               // the payload is a reference counter used to manage the
                // list. when it is non-zero the signal in known to be inactive
-               std::map<int, int> known_inactive;
+               vector<int> known_inactive;
 
                // database of known active signals
-               // the 2nd dimension is the list of or-ed signals. so we know that
-               // for each i there is a j so that known_active[i][j] points to an
-               // active control signal.
-               std::vector<std::vector<int>> known_active;
+               vector<int> known_active;
 
                // this is just used to keep track of visited muxes in order to prohibit
                // endless recursion in mux loops
-               std::set<int> visited_muxes;
+               vector<bool> visited_muxes;
        };
 
        void eval_mux_port(knowledge_t &knowledge, int mux_idx, int port_idx)
        {
                muxinfo_t &muxinfo = mux2info[mux_idx];
+
+               if (muxinfo.ports[port_idx].const_deactivated)
+                       return;
+
                muxinfo.ports[port_idx].enabled = true;
 
-               for (size_t i = 0; i < muxinfo.ports.size(); i++) {
-                       if (int(i) == port_idx)
+               for (int i = 0; i < GetSize(muxinfo.ports); i++) {
+                       if (i == port_idx)
                                continue;
-                       for (int b : muxinfo.ports[i].ctrl_sigs)
-                               knowledge.known_inactive[b]++;
+                       if (muxinfo.ports[i].ctrl_sig >= 0)
+                               knowledge.known_inactive.at(muxinfo.ports[i].ctrl_sig)++;
                }
 
                if (port_idx < int(muxinfo.ports.size())-1 && !muxinfo.ports[port_idx].const_activated)
-                       knowledge.known_active.push_back(muxinfo.ports[port_idx].ctrl_sigs);
+                       knowledge.known_active.at(muxinfo.ports[port_idx].ctrl_sig)++;
 
-               std::vector<int> parent_muxes;
+               vector<int> parent_muxes;
                for (int m : muxinfo.ports[port_idx].input_muxes) {
-                       if (knowledge.visited_muxes.count(m) > 0)
+                       if (knowledge.visited_muxes[m])
                                continue;
-                       knowledge.visited_muxes.insert(m);
+                       knowledge.visited_muxes[m] = true;
                        parent_muxes.push_back(m);
                }
                for (int m : parent_muxes)
-                       if (!root_muxes.count(m))
+                       if (!root_muxes.at(m))
                                eval_mux(knowledge, m);
                for (int m : parent_muxes)
-                       knowledge.visited_muxes.erase(m);
+                       knowledge.visited_muxes[m] = false;
 
                if (port_idx < int(muxinfo.ports.size())-1 && !muxinfo.ports[port_idx].const_activated)
-                       knowledge.known_active.pop_back();
+                       knowledge.known_active.at(muxinfo.ports[port_idx].ctrl_sig)--;
 
                for (size_t i = 0; i < muxinfo.ports.size(); i++) {
                        if (int(i) == port_idx)
                                continue;
-                       for (int b : muxinfo.ports[i].ctrl_sigs)
-                               knowledge.known_inactive[b]--;
+                       if (muxinfo.ports[i].ctrl_sig >= 0)
+                               knowledge.known_inactive.at(muxinfo.ports[i].ctrl_sig)--;
                }
        }
 
@@ -351,20 +343,17 @@ struct OptMuxtreeWorker
                SigSpec sig = muxinfo.cell->getPort(portname);
                bool did_something = false;
 
-               std::vector<int> bits = sig2bits(sig, false);
+               vector<int> bits = sig2bits(sig, false);
                for (int i = 0; i < GetSize(bits); i++) {
                        if (bits[i] < 0)
                                continue;
-                       if (knowledge.known_inactive[bits[i]]) {
+                       if (knowledge.known_inactive.at(bits[i])) {
                                sig[i] = State::S0;
                                did_something = true;
-                       } else {
-                               for (auto &it : knowledge.known_active)
-                                       if (GetSize(it) == 1 && it.front() == bits[i]) {
-                                               sig[i] = State::S1;
-                                               did_something = true;
-                                               break;
-                                       }
+                       } else
+                       if (knowledge.known_active.at(bits[i])) {
+                               sig[i] = State::S1;
+                               did_something = true;
                        }
                }
 
@@ -399,16 +388,14 @@ struct OptMuxtreeWorker
                for (size_t port_idx = 0; port_idx < muxinfo.ports.size()-1; port_idx++)
                {
                        portinfo_t &portinfo = muxinfo.ports[port_idx];
-                       for (size_t i = 0; i < knowledge.known_active.size(); i++) {
-                               if (list_is_subset(knowledge.known_active[i], portinfo.ctrl_sigs)) {
-                                       eval_mux_port(knowledge, mux_idx, port_idx);
-                                       return;
-                               }
+                       if (knowledge.known_active.at(portinfo.ctrl_sig)) {
+                               eval_mux_port(knowledge, mux_idx, port_idx);
+                               return;
                        }
                }
 
-               // compare ports with known_inactive and known_active signals. If all control
-               // signals of the port are known_inactive or if the control signals of all other
+               // compare ports with known_inactive and known_active signals. If the control
+               // signal of the port is known_inactive or if the control signals of all other
                // ports are known_active this port can't be activated. this loop includes the
                // default port but no known_inactive match is performed on the default port.
                for (size_t port_idx = 0; port_idx < muxinfo.ports.size(); port_idx++)
@@ -417,23 +404,17 @@ struct OptMuxtreeWorker
 
                        if (port_idx < muxinfo.ports.size()-1) {
                                bool found_non_known_inactive = false;
-                               for (int i : portinfo.ctrl_sigs)
-                                       if (knowledge.known_inactive[i] == 0)
-                                               found_non_known_inactive = true;
+                               if (knowledge.known_inactive.at(portinfo.ctrl_sig) == 0)
+                                       found_non_known_inactive = true;
                                if (!found_non_known_inactive)
                                        continue;
                        }
 
                        bool port_active = true;
-                       std::vector<int> other_ctrl_sig;
                        for (size_t i = 0; i < muxinfo.ports.size()-1; i++) {
                                if (i == port_idx)
                                        continue;
-                               other_ctrl_sig.insert(other_ctrl_sig.end(),
-                                               muxinfo.ports[i].ctrl_sigs.begin(), muxinfo.ports[i].ctrl_sigs.end());
-                       }
-                       for (size_t i = 0; i < knowledge.known_active.size(); i++) {
-                               if (list_is_subset(knowledge.known_active[i], other_ctrl_sig))
+                               if (knowledge.known_active.at(muxinfo.ports[i].ctrl_sig))
                                        port_active = false;
                        }
                        if (port_active)
@@ -444,7 +425,10 @@ struct OptMuxtreeWorker
        void eval_root_mux(int mux_idx)
        {
                knowledge_t knowledge;
-               knowledge.visited_muxes.insert(mux_idx);
+               knowledge.known_inactive.resize(bit2info.size());
+               knowledge.known_active.resize(bit2info.size());
+               knowledge.visited_muxes.resize(mux2info.size());
+               knowledge.visited_muxes[mux_idx] = true;
                eval_mux(knowledge, mux_idx);
        }
 };
@@ -464,7 +448,7 @@ struct OptMuxtreePass : public Pass {
                log("This pass only operates on completely selected modules without processes.\n");
                log("\n");
        }
-       virtual void execute(std::vector<std::string> args, RTLIL::Design *design)
+       virtual void execute(vector<std::string> args, RTLIL::Design *design)
        {
                log_header("Executing OPT_MUXTREE pass (detect dead branches in mux trees).\n");
                extra_args(args, 1, design);