3 files changed, 25 insertions, 10 deletions
diff --git a/kernel/driver.cc b/kernel/driver.cc
index 65b6c5a4..e95ef48d 100644
--- a/kernel/driver.cc
+++ b/kernel/driver.cc
@@ -291,7 +291,7 @@ int main(int argc, char **argv)
 	}
 
 	while (optind < argc)
-		run_frontend(argv[optind++], frontend_command, yosys_design, output_filename == "-" ? &backend_command : NULL, NULL);
+		run_frontend(argv[optind++], frontend_command, output_filename == "-" ? &backend_command : NULL);
 
 	if (!scriptfile.empty()) {
 		if (scriptfile_tcl) {
@@ -302,14 +302,14 @@ int main(int argc, char **argv)
 			log_error("Can't exectue TCL script: this version of yosys is not built with TCL support enabled.\n");
 #endif
 		} else
-			run_frontend(scriptfile, "script", yosys_design, output_filename == "-" ? &backend_command : NULL, NULL);
+			run_frontend(scriptfile, "script", output_filename == "-" ? &backend_command : NULL);
 	}
 
 	for (auto it = passes_commands.begin(); it != passes_commands.end(); it++)
-		run_pass(*it, yosys_design);
+		run_pass(*it);
 
 	if (!backend_command.empty())
-		run_backend(output_filename, backend_command, yosys_design);
+		run_backend(output_filename, backend_command);
 
 	if (print_stats)
 	{
diff --git a/kernel/yosys.cc b/kernel/yosys.cc
index e4a5c335..530d7879 100644
--- a/kernel/yosys.cc
+++ b/kernel/yosys.cc
@@ -679,8 +679,11 @@ static void handle_label(std::string &command, bool &from_to_active, const std::
 	}
 }
 
-void run_frontend(std::string filename, std::string command, RTLIL::Design *design, std::string *backend_command, std::string *from_to_label)
+void run_frontend(std::string filename, std::string command, std::string *backend_command, std::string *from_to_label, RTLIL::Design *design)
 {
+	if (design == nullptr)
+		design = yosys_design;
+
 	if (command == "auto") {
 		if (filename.size() > 2 && filename.substr(filename.size()-2) == ".v")
 			command = "verilog";
@@ -772,8 +775,16 @@ void run_frontend(std::string filename, std::string command, RTLIL::Design *desi
 	Frontend::frontend_call(design, NULL, filename, command);
 }
 
+void run_frontend(std::string filename, std::string command, RTLIL::Design *design)
+{
+	run_frontend(filename, command, nullptr, nullptr, design);
+}
+
 void run_pass(std::string command, RTLIL::Design *design)
 {
+	if (design == nullptr)
+		design = yosys_design;
+
 	log("\n-- Running command `%s' --\n", command.c_str());
 
 	Pass::call(design, command);
@@ -781,6 +792,9 @@ void run_pass(std::string command, RTLIL::Design *design)
 
 void run_backend(std::string filename, std::string command, RTLIL::Design *design)
 {
+	if (design == nullptr)
+		design = yosys_design;
+
 	if (command == "auto") {
 		if (filename.size() > 2 && filename.substr(filename.size()-2) == ".v")
 			command = "verilog";
@@ -1025,9 +1039,9 @@ struct ScriptPass : public Pass {
 		if (args.size() < 2)
 			log_cmd_error("Missing script file.\n");
 		else if (args.size() == 2)
-			run_frontend(args[1], "script", design, NULL, NULL);
+			run_frontend(args[1], "script", design);
 		else if (args.size() == 3)
-			run_frontend(args[1], "script", design, NULL, &args[2]);
+			run_frontend(args[1], "script", NULL, &args[2], design);
 		else
 			extra_args(args, 2, design, false);
 	}
diff --git a/kernel/yosys.h b/kernel/yosys.h
index efdc005e..47275ecd 100644
--- a/kernel/yosys.h
+++ b/kernel/yosys.h
@@ -253,9 +253,10 @@ std::string proc_self_dirname();
 std::string proc_share_dirname();
 const char *create_prompt(RTLIL::Design *design, int recursion_counter);
 
-void run_frontend(std::string filename, std::string command, RTLIL::Design *design, std::string *backend_command, std::string *from_to_label);
-void run_pass(std::string command, RTLIL::Design *design);
-void run_backend(std::string filename, std::string command, RTLIL::Design *design);
+void run_pass(std::string command, RTLIL::Design *design = nullptr);
+void run_frontend(std::string filename, std::string command, std::string *backend_command, std::string *from_to_label = nullptr, RTLIL::Design *design = nullptr);
+void run_frontend(std::string filename, std::string command, RTLIL::Design *design = nullptr);
+void run_backend(std::string filename, std::string command, RTLIL::Design *design = nullptr);
 void shell(RTLIL::Design *design);
 
 // from kernel/version_*.o (cc source generated from Makefile)