synth_sf2: add -discard-ffinit option to discard ff initial value

sf2 ff have no initial values, but some IP cores use initial values.
In order to use those cores on sf2, it is required to discard the
initial value (to be carefully used).

1 files changed, 11 insertions, 1 deletions

diff --git a/techlibs/sf2/synth_sf2.cc b/techlibs/sf2/synth_sf2.cc
index f78b4f012..fcc0a5e23 100644
--- a/techlibs/sf2/synth_sf2.cc
+++ b/techlibs/sf2/synth_sf2.cc
@@ -66,6 +66,9 @@ struct SynthSf2Pass : public ScriptPass
 		log("    -clkbuf\n");
 		log("        insert direct PAD->global_net buffers\n");
 		log("\n");
+		log("    -discard-ffinit\n");
+		log("        discard FF init value instead of emitting an error\n");
+		log("\n");
 		log("    -retime\n");
 		log("        run 'abc' with '-dff -D 1' options\n");
 		log("\n");
@@ -76,7 +79,7 @@ struct SynthSf2Pass : public ScriptPass
 	}
 
 	string top_opt, edif_file, vlog_file, json_file;
-	bool flatten, retime, iobs, clkbuf;
+	bool flatten, retime, iobs, clkbuf, discard_ffinit;
 
 	void clear_flags() override
 	{
@@ -88,6 +91,7 @@ struct SynthSf2Pass : public ScriptPass
 		retime = false;
 		iobs = true;
 		clkbuf = false;
+		discard_ffinit = false;
 	}
 
 	void execute(std::vector<std::string> args, RTLIL::Design *design) override
@@ -138,6 +142,10 @@ struct SynthSf2Pass : public ScriptPass
 				clkbuf = true;
 				continue;
 			}
+			if (args[argidx] == "-discard-ffinit") {
+				discard_ffinit = true;
+				continue;
+			}
 			break;
 		}
 		extra_args(args, argidx, design);
@@ -171,6 +179,8 @@ struct SynthSf2Pass : public ScriptPass
 
 		if (check_label("coarse"))
 		{
+			if (discard_ffinit || help_mode)
+				run("attrmap -remove init", "(only if -discard-ffinit)");
 			run("synth -run coarse");
 		}