synth_xilinx -widemux=2 is minimum now

diff --git a/techlibs/xilinx/synth_xilinx.cc b/techlibs/xilinx/synth_xilinx.cc
index f43923afb628cadb2c47fba291bfd4d312aa9645..4f597de4dc7f939efeb656a42185aaff2afb07ec 100644 (file)
--- a/techlibs/xilinx/synth_xilinx.cc
+++ b/techlibs/xilinx/synth_xilinx.cc
@@ -79,7 +79,7 @@ struct SynthXilinxPass : public ScriptPass
                log("\n");
                log("    -widemux <int>\n");
                log("        enable inference of hard multiplexer resources (MuxFx) for muxes at or\n");
-               log("        above this number of inputs (minimum value 5).\n");
+               log("        above this number of inputs (minimum value 2).\n");
                log("        default: 0 (no inference)\n");
                log("\n");
                log("    -run <from_label>:<to_label>\n");
@@ -208,8 +208,8 @@ struct SynthXilinxPass : public ScriptPass
                if (family != "xcup" && family != "xcu" && family != "xc7" && family != "xc6s")
                        log_cmd_error("Invalid Xilinx -family setting: %s\n", family.c_str());
 
-               if (widemux != 0 && widemux < 5)
-                       log_cmd_error("-widemux value must be 0 or >= 5.\n");
+               if (widemux != 0 && widemux < 2)
+                       log_cmd_error("-widemux value must be 0 or >= 2.\n");
 
                if (!design->full_selection())
                        log_cmd_error("This command only operates on fully selected designs!\n");
@@ -252,7 +252,7 @@ struct SynthXilinxPass : public ScriptPass
                        //   so attempt to convert $pmux-es to the former
                        // Also: wide multiplexer inference benefits from this too
                        if (!(nosrl && widemux == 0) || help_mode)
-                               run("pmux2shiftx", "(skip if '-nosrl' and '-widemux' < 5)");
+                               run("pmux2shiftx", "(skip if '-nosrl' and '-widemux=0')");
                }
 
                if (check_label("bram", "(skip if '-nobram')")) {
@@ -283,6 +283,9 @@ struct SynthXilinxPass : public ScriptPass
                                constexpr int cost_mux2 = 100;
                                std::string muxcover_args = stringf(" -nodecode -mux2=%d", cost_mux2);
                                switch (widemux) {
+                                       case  2:
+                                       case  3:
+                                       case  4: muxcover_args += stringf(" -mux4=%d -mux8=%d -mux16=%d", cost_mux2*(widemux-1)-2, cost_mux2*(widemux-1)-1, cost_mux2*(widemux-1)); break;
                                        case  5:
                                        case  6:
                                        case  7: