From 1ec6429bad4d793b389ee594b1cb2575bf73ddaf Mon Sep 17 00:00:00 2001
From: Clifford Wolf <clifford@clifford.at>
Date: Sat, 7 Nov 2015 19:10:43 +0100
Subject: [PATCH] Added "singleton" pass

---
 passes/hierarchy/Makefile.inc |   1 +
 passes/hierarchy/singleton.cc | 101 ++++++++++++++++++++++++++++++++++
 2 files changed, 102 insertions(+)
 create mode 100644 passes/hierarchy/singleton.cc

diff --git a/passes/hierarchy/Makefile.inc b/passes/hierarchy/Makefile.inc
index 99aa1e116..1fb669c11 100644
--- a/passes/hierarchy/Makefile.inc
+++ b/passes/hierarchy/Makefile.inc
@@ -1,4 +1,5 @@
 
 OBJS += passes/hierarchy/hierarchy.o
+OBJS += passes/hierarchy/singleton.o
 OBJS += passes/hierarchy/submod.o
 
diff --git a/passes/hierarchy/singleton.cc b/passes/hierarchy/singleton.cc
new file mode 100644
index 000000000..5715c0eb1
--- /dev/null
+++ b/passes/hierarchy/singleton.cc
@@ -0,0 +1,101 @@
+/*
+ *  yosys -- Yosys Open SYnthesis Suite
+ *
+ *  Copyright (C) 2012  Clifford Wolf <clifford@clifford.at>
+ *
+ *  Permission to use, copy, modify, and/or distribute this software for any
+ *  purpose with or without fee is hereby granted, provided that the above
+ *  copyright notice and this permission notice appear in all copies.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ *  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ *  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ *  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ *  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ *  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ *  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ */
+
+#include "kernel/yosys.h"
+
+USING_YOSYS_NAMESPACE
+PRIVATE_NAMESPACE_BEGIN
+
+struct SingletonPass : public Pass {
+	SingletonPass() : Pass("singleton", "create singleton modules") { }
+	virtual void help()
+	{
+		//   |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
+		log("\n");
+		log("    singleton [selection]\n");
+		log("\n");
+		log("By default, a module that is instantiated by several other modules is only\n");
+		log("kept once in the design. This preserves the original modularity of the design\n");
+		log("and reduces the overall size of the design in memory. But it prevents certain\n");
+		log("optimizations and other operations on the design. This pass creates singleton\n");
+		log("modules for all selected cells. The created modules are marked with the\n");
+		log("'singleton' attribute.\n");
+		log("\n");
+		log("This commands only operates on modules that by themself have the 'singleton'\n");
+		log("attribute set (the 'top' module is a singleton implicitly).\n");
+		log("\n");
+	}
+	virtual void execute(std::vector<std::string> args, RTLIL::Design *design)
+	{
+		log_header("Executing SINGLETON pass (creating singleton modules).\n");
+
+		size_t argidx;
+		for (argidx = 1; argidx < args.size(); argidx++)
+		{
+			// if (args[argidx] == "-check") {
+			// 	flag_check = true;
+			// 	continue;
+			// }
+		}
+		extra_args(args, argidx, design);
+
+		bool did_something = true;
+		int singleton_cnt = 0;
+
+		while (did_something)
+		{
+			did_something = false;
+
+			for (auto module : design->selected_modules())
+			{
+				if (!module->get_bool_attribute("\\singleton") && !module->get_bool_attribute("\\top"))
+					continue;
+
+				for (auto cell : module->selected_cells())
+				{
+					auto tmod = design->module(cell->type);
+
+					if (tmod == nullptr)
+						continue;
+
+					if (tmod->get_bool_attribute("\\blackbox"))
+						continue;
+
+					if (tmod->get_bool_attribute("\\singleton"))
+						continue;
+
+					cell->type = module->name.str() + "." + log_id(cell->name);
+					log("Creating singleton '%s'.\n", log_id(cell->type));
+
+					auto smod = tmod->clone();
+					smod->name = cell->type;
+					smod->set_bool_attribute("\\singleton");
+					design->add(smod);
+
+					did_something = true;
+					singleton_cnt++;
+				}
+			}
+		}
+
+		log("Created %d singleton modules.\n", singleton_cnt);
+	}
+} SingletonPass;
+
+PRIVATE_NAMESPACE_END
-- 
2.30.2