use singleton ground and vcc nets, apparently this makes pnr happier

diff --git a/techlibs/gowin/synth_gowin.cc b/techlibs/gowin/synth_gowin.cc
index 4d32f62d4a6d17d37020ddd7f4f3f7c0d9fb04a2..3581d050ec63b0bbbfdfcd473abbd3fb1098cf89 100644 (file)
--- a/techlibs/gowin/synth_gowin.cc
+++ b/techlibs/gowin/synth_gowin.cc
@@ -212,7 +212,7 @@ struct SynthGowinPass : public ScriptPass
                {
                        run("techmap -map +/gowin/cells_map.v");
                        run("setundef -undriven -zero");
-                       run("hilomap -hicell VCC V -locell GND G");
+                       run("hilomap -singleton -hicell VCC V -locell GND G");
                        run("iopadmap -bits -inpad IBUF O:I -outpad OBUF I:O", "(unless -noiopads)");
                        run("dffinit  -ff DFF Q INIT");
                        run("clean");