5 files changed, 39 insertions, 3 deletions

diff --git a/frontends/ilang/ilang_frontend.cc b/frontends/ilang/ilang_frontend.cc
index 6b302a796..30d9ff79d 100644
--- a/frontends/ilang/ilang_frontend.cc
+++ b/frontends/ilang/ilang_frontend.cc
@@ -47,16 +47,20 @@ struct IlangFrontend : public Frontend {
 		log("    -nooverwrite\n");
 		log("        ignore re-definitions of modules. (the default behavior is to\n");
 		log("        create an error message if the existing module is not a blackbox\n");
-		log("        module, and overwrite the existing module if it is  a blackbox module.)\n");
+		log("        module, and overwrite the existing module if it is a blackbox module.)\n");
 		log("\n");
 		log("    -overwrite\n");
 		log("        overwrite existing modules with the same name\n");
 		log("\n");
+		log("    -lib\n");
+		log("        only create empty blackbox modules\n");
+		log("\n");
 	}
 	void execute(std::istream *&f, std::string filename, std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
 	{
 		ILANG_FRONTEND::flag_nooverwrite = false;
 		ILANG_FRONTEND::flag_overwrite = false;
+		ILANG_FRONTEND::flag_lib = false;
 
 		log_header(design, "Executing ILANG frontend.\n");
 
@@ -73,6 +77,10 @@ struct IlangFrontend : public Frontend {
 				ILANG_FRONTEND::flag_overwrite = true;
 				continue;
 			}
+			if (arg == "-lib") {
+				ILANG_FRONTEND::flag_lib = true;
+				continue;
+			}
 			break;
 		}
 		extra_args(f, filename, args, argidx);
diff --git a/frontends/ilang/ilang_frontend.h b/frontends/ilang/ilang_frontend.h
index 052dd4cb2..f8a152841 100644
--- a/frontends/ilang/ilang_frontend.h
+++ b/frontends/ilang/ilang_frontend.h
@@ -34,6 +34,7 @@ namespace ILANG_FRONTEND {
 	extern RTLIL::Design *current_design;
 	extern bool flag_nooverwrite;
 	extern bool flag_overwrite;
+	extern bool flag_lib;
 }
 
 YOSYS_NAMESPACE_END
diff --git a/frontends/ilang/ilang_parser.y b/frontends/ilang/ilang_parser.y
index 5bcc01f42..f83824088 100644
--- a/frontends/ilang/ilang_parser.y
+++ b/frontends/ilang/ilang_parser.y
@@ -37,7 +37,7 @@ namespace ILANG_FRONTEND {
 	std::vector<std::vector<RTLIL::SwitchRule*>*> switch_stack;
 	std::vector<RTLIL::CaseRule*> case_stack;
 	dict<RTLIL::IdString, RTLIL::Const> attrbuf;
-	bool flag_nooverwrite, flag_overwrite;
+	bool flag_nooverwrite, flag_overwrite, flag_lib;
 	bool delete_current_module;
 }
 using namespace ILANG_FRONTEND;
@@ -98,7 +98,7 @@ module:
 		delete_current_module = false;
 		if (current_design->has($2)) {
 			RTLIL::Module *existing_mod = current_design->module($2);
-			if (!flag_overwrite && attrbuf.count("\\blackbox") && attrbuf.at("\\blackbox").as_bool()) {
+			if (!flag_overwrite && (flag_lib || (attrbuf.count("\\blackbox") && attrbuf.at("\\blackbox").as_bool()))) {
 				log("Ignoring blackbox re-definition of module %s.\n", $2);
 				delete_current_module = true;
 			} else if (!flag_nooverwrite && !flag_overwrite && !existing_mod->get_bool_attribute("\\blackbox")) {
@@ -124,6 +124,8 @@ module:
 		current_module->fixup_ports();
 		if (delete_current_module)
 			delete current_module;
+		else if (flag_lib)
+			current_module->makeblackbox();
 		current_module = nullptr;
 	} EOL;
 
diff --git a/kernel/rtlil.cc b/kernel/rtlil.cc
index b3214579d..9ae20a317 100644
--- a/kernel/rtlil.cc
+++ b/kernel/rtlil.cc
@@ -641,6 +641,30 @@ RTLIL::Module::~Module()
 		delete it->second;
 }
 
+void RTLIL::Module::makeblackbox()
+{
+	pool<RTLIL::Wire*> delwires;
+
+	for (auto it = wires_.begin(); it != wires_.end(); ++it)
+		if (!it->second->port_input && !it->second->port_output)
+			delwires.insert(it->second);
+
+	for (auto it = memories.begin(); it != memories.end(); ++it)
+		delete it->second;
+	memories.clear();
+
+	for (auto it = cells_.begin(); it != cells_.end(); ++it)
+		delete it->second;
+	cells_.clear();
+
+	for (auto it = processes.begin(); it != processes.end(); ++it)
+		delete it->second;
+	processes.clear();
+
+	remove(delwires);
+	set_bool_attribute("\\blackbox");
+}
+
 void RTLIL::Module::reprocess_module(RTLIL::Design *, dict<RTLIL::IdString, RTLIL::Module *>)
 {
 	log_error("Cannot reprocess_module module `%s' !\n", id2cstr(name));
diff --git a/kernel/rtlil.h b/kernel/rtlil.h
index 52496e702..fb045bc72 100644
--- a/kernel/rtlil.h
+++ b/kernel/rtlil.h
@@ -976,6 +976,7 @@ public:
 	virtual void sort();
 	virtual void check();
 	virtual void optimize();
+	virtual void makeblackbox();
 
 	void connect(const RTLIL::SigSig &conn);
 	void connect(const RTLIL::SigSpec &lhs, const RTLIL::SigSpec &rhs);