Add synth -keepdc option

diff --git a/techlibs/common/synth.cc b/techlibs/common/synth.cc
index 555de9fba1568580f6536fefc5c41eba5dcc25c4..af70cc4983e0d4d1a132385c918304e5e0185e01 100644 (file)
--- a/techlibs/common/synth.cc
+++ b/techlibs/common/synth.cc
@@ -78,6 +78,9 @@ struct SynthPass : public ScriptPass
                log("    -abc9\n");
                log("        use new ABC9 flow (EXPERIMENTAL)\n");
                log("\n");
+               log("    -keepdc\n");
+               log("        do not optimize explicit don't-care values on $mux cells.\n");
+               log("\n");
                log("\n");
                log("The following commands are executed by this synthesis command:\n");
                help_script();
@@ -85,7 +88,7 @@ struct SynthPass : public ScriptPass
        }
 
        string top_module, fsm_opts, memory_opts, abc;
-       bool autotop, flatten, noalumacc, nofsm, noabc, noshare;
+       bool autotop, flatten, noalumacc, nofsm, noabc, noshare, keepdc;
        int lut;
 
        void clear_flags() YS_OVERRIDE
@@ -102,6 +105,7 @@ struct SynthPass : public ScriptPass
                noabc = false;
                noshare = false;
                abc = "abc";
+               keepdc = false;
        }
 
        void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
@@ -167,6 +171,10 @@ struct SynthPass : public ScriptPass
                                abc = "abc9";
                                continue;
                        }
+                       if (args[argidx] == "-keepdc") {
+                               keepdc = true;
+                               continue;
+                       }
                        break;
                }
                extra_args(args, argidx, design);
@@ -211,7 +219,10 @@ struct SynthPass : public ScriptPass
                        run("opt_clean");
                        run("check");
                        run("opt");
-                       run("wreduce");
+                       if (help_mode)
+                               run("wreduce [-keepdc]");
+                       else
+                               run("wreduce" + std::string(keepdc ? " -keepdc" : ""));
                        run("peepopt");
                        run("opt_clean");
                        if (help_mode)