Improvements in "pmux2shiftx"

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

diff --git a/passes/opt/pmux2shiftx.cc b/passes/opt/pmux2shiftx.cc
index d0f41cb0721530376a20dbcf0b8b0bb7e85c9d1b..e6a0bd06bfb03e8e8f997b0614a3807a41387dfd 100644 (file)
--- a/passes/opt/pmux2shiftx.cc
+++ b/passes/opt/pmux2shiftx.cc
@@ -33,23 +33,41 @@ struct Pmux2ShiftxPass : public Pass {
                log("\n");
                log("This pass transforms $pmux cells to $shiftx cells.\n");
                log("\n");
-               log("    -density non_offset_percentage offset_percentage\n");
+               log("    -min_density <non_offset_percentage> <offset_percentage>\n");
                log("        specifies the minimum density for non_offset- and for offset-mode\n");
                log("        default values are 30 (non-offset) and 50 (offset)\n");
                log("\n");
+               log("    -min_choices <int>\n");
+               log("        specified the minimum number of choices for a control signal\n");
+               log("        defaukt: 3\n");
+               log("\n");
+               log("    -allow_onehot\n");
+               log("        by default, pmuxes with one-hot encoded control signals are not\n");
+               log("        converted. this option disables that check.\n");
+               log("\n");
        }
        void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
        {
-               int non_offset_percentage = 30;
-               int offset_percentage = 50;
+               int min_non_offset_percentage = 30;
+               int min_offset_percentage = 50;
+               int min_choices = 3;
+               bool allow_onehot = false;
 
                log_header(design, "Executing PMUX2SHIFTX pass.\n");
 
                size_t argidx;
                for (argidx = 1; argidx < args.size(); argidx++) {
-                       if (args[argidx] == "-density" && argidx+2 < args.size()) {
-                               non_offset_percentage = atoi(args[++argidx].c_str());
-                               offset_percentage = atoi(args[++argidx].c_str());
+                       if (args[argidx] == "-min_density" && argidx+2 < args.size()) {
+                               min_non_offset_percentage = atoi(args[++argidx].c_str());
+                               min_offset_percentage = atoi(args[++argidx].c_str());
+                               continue;
+                       }
+                       if (args[argidx] == "-min_choices" && argidx+1 < args.size()) {
+                               min_choices = atoi(args[++argidx].c_str());
+                               continue;
+                       }
+                       if (args[argidx] == "-allow_onehot") {
+                               allow_onehot = true;
                                continue;
                        }
                        break;
@@ -163,8 +181,7 @@ struct Pmux2ShiftxPass : public Pass {
                                if (seldb.empty())
                                        continue;
 
-                               log("Inspecting $pmux cell %s/%s.\n", log_id(module), log_id(cell));
-                               log("  data width: %d (next power-of-2 = %d, log2 = %d)\n", width, extwidth, width_bits);
+                               bool printed_pmux_header = false;
 
                                SigSpec updated_S = cell->getPort("\\S");
                                SigSpec updated_B = cell->getPort("\\B");
@@ -180,17 +197,40 @@ struct Pmux2ShiftxPass : public Pass {
                                                        sig = it.first;
                                        }
 
-                                       log("  checking ctrl signal %s\n", log_signal(sig));
-
                                        // find the relevant choices
+                                       bool is_onehot = true;
                                        dict<Const, int> choices;
                                        for (int i : seldb.at(sig)) {
                                                Const val = eqdb.at(S[i]).second;
+                                               int onebits = 0;
+                                               for (auto b : val.bits)
+                                                       if (b == State::S1)
+                                                               onebits++;
+                                               if (onebits > 1)
+                                                       is_onehot = false;
                                                choices[val] = i;
                                        }
 
                                        // TBD: also find choices that are using signals that are subsets of the bits in "sig"
 
+                                       if (is_onehot && !allow_onehot) {
+                                               seldb.erase(sig);
+                                               continue;
+                                       }
+
+                                       if (GetSize(choices) < min_choices) {
+                                               seldb.erase(sig);
+                                               continue;
+                                       }
+
+                                       if (!printed_pmux_header) {
+                                               printed_pmux_header = true;
+                                               log("Inspecting $pmux cell %s/%s.\n", log_id(module), log_id(cell));
+                                               log("  data width: %d (next power-of-2 = %d, log2 = %d)\n", width, extwidth, width_bits);
+                                       }
+
+                                       log("  checking ctrl signal %s\n", log_signal(sig));
+
                                        // find the best permutation
                                        vector<int> perm_new_from_old(GetSize(sig));
                                        Const perm_xormask(State::S0, GetSize(sig));
@@ -329,7 +369,7 @@ struct Pmux2ShiftxPass : public Pass {
 
                                        // check density percentages
                                        Const offset(State::S0, GetSize(sig));
-                                       if (absolute_density < non_offset_percentage && range_density >= offset_percentage)
+                                       if (absolute_density < min_non_offset_percentage && range_density >= min_offset_percentage)
                                        {
                                                offset = Const(min_choice, GetSize(sig));
                                                log("    offset: %s\n", log_signal(offset));
@@ -342,7 +382,7 @@ struct Pmux2ShiftxPass : public Pass {
                                                        new_perm_choices[const_sub(it.first, offset, false, false, GetSize(sig))] = it.second;
                                                perm_choices.swap(new_perm_choices);
                                        } else
-                                       if (absolute_density < non_offset_percentage) {
+                                       if (absolute_density < min_non_offset_percentage) {
                                                log("    insufficient density.\n");
                                                seldb.erase(sig);
                                                continue;

diff --git a/tests/various/pmux2shiftx.ys b/tests/various/pmux2shiftx.ys
index f5e83171cb0b84be8673f713af5162462f73ad60..f84ae38692e629ca599df266190c28d3009203a7 100644 (file)
--- a/tests/various/pmux2shiftx.ys
+++ b/tests/various/pmux2shiftx.ys
@@ -2,7 +2,7 @@ read_verilog pmux2shiftx.v
 prep
 design -save gold
 
-pmux2shiftx -density 70 50
+pmux2shiftx -min_density 70 50
 
 opt