3 files changed, 43 insertions, 0 deletions

diff --git a/kernel/rtlil.cc b/kernel/rtlil.cc
index 5deef850..7cd2dd4b 100644
--- a/kernel/rtlil.cc
+++ b/kernel/rtlil.cc
@@ -316,6 +316,21 @@ RTLIL::Module *RTLIL::Design::module(RTLIL::IdString name)
 	return modules_.count(name) ? modules_.at(name) : NULL;
 }
 
+RTLIL::Module *RTLIL::Design::top_module()
+{
+	RTLIL::Module *module = nullptr;
+	int module_count = 0;
+
+	for (auto mod : selected_modules()) {
+		if (mod->get_bool_attribute("\\top"))
+			return mod;
+		module_count++;
+		module = mod;
+	}
+
+	return module_count == 1 ? module : nullptr;
+}
+
 void RTLIL::Design::add(RTLIL::Module *module)
 {
 	log_assert(modules_.count(module->name) == 0);
diff --git a/kernel/rtlil.h b/kernel/rtlil.h
index e9deb1d5..b6248c4c 100644
--- a/kernel/rtlil.h
+++ b/kernel/rtlil.h
@@ -800,6 +800,7 @@ struct RTLIL::Design
 
 	RTLIL::ObjRange<RTLIL::Module*> modules();
 	RTLIL::Module *module(RTLIL::IdString name);
+	RTLIL::Module *top_module();
 
 	bool has(RTLIL::IdString id) const {
 		return modules_.count(id) != 0;
diff --git a/passes/cmds/rename.cc b/passes/cmds/rename.cc
index 17d803e9..d1671317 100644
--- a/passes/cmds/rename.cc
+++ b/passes/cmds/rename.cc
@@ -76,12 +76,17 @@ struct RenamePass : public Pass {
 		log("Assign private names (the ones with $-prefix) to all selected wires and cells\n");
 		log("with public names. This ignores all selected ports.\n");
 		log("\n");
+		log("    rename -top new_name\n");
+		log("\n");
+		log("Rename top module.\n");
+		log("\n");
 	}
 	virtual void execute(std::vector<std::string> args, RTLIL::Design *design)
 	{
 		std::string pattern_prefix = "_", pattern_suffix = "_";
 		bool flag_enumerate = false;
 		bool flag_hide = false;
+		bool flag_top = false;
 		bool got_mode = false;
 
 		size_t argidx;
@@ -98,6 +103,11 @@ struct RenamePass : public Pass {
 				got_mode = true;
 				continue;
 			}
+			if (arg == "-top" && !got_mode) {
+				flag_top = true;
+				got_mode = true;
+				continue;
+			}
 			if (arg == "-pattern" && argidx+1 < args.size() && args[argidx+1].find('%') != std::string::npos) {
 				int pos = args[++argidx].find('%');
 				pattern_prefix = args[argidx].substr(0, pos);
@@ -171,6 +181,23 @@ struct RenamePass : public Pass {
 			}
 		}
 		else
+		if (flag_top)
+		{
+			if (argidx+1 != args.size())
+				log_cmd_error("Invalid number of arguments!\n");
+
+			IdString new_name = RTLIL::escape_id(args[argidx]);
+			RTLIL::Module *module = design->top_module();
+
+			if (module == NULL)
+				log_cmd_error("No top module found!\n");
+
+			log("Renaming module %s to %s.\n", log_id(module), log_id(new_name));
+			design->modules_.erase(module->name);
+			module->name = new_name;
+			design->modules_[module->name] = module;
+		}
+		else
 		{
 			if (argidx+2 != args.size())
 				log_cmd_error("Invalid number of arguments!\n");