Add bwmuxmap pass

backends/btor/btor.cc

@@ -1417,6 +1417,7 @@ struct BtorBackend : public Backend {
 		log_push();
 		Pass::call(design, "bmuxmap");
 		Pass::call(design, "demuxmap");
+		Pass::call(design, "bwmuxmap");
 		log_pop();
 
 		size_t argidx;

backends/firrtl/firrtl.cc

@@ -1215,6 +1215,7 @@ struct FirrtlBackend : public Backend {
 		Pass::call(design, "pmuxtree");
 		Pass::call(design, "bmuxmap");
 		Pass::call(design, "demuxmap");
+		Pass::call(design, "bwmuxmap");
 
 		namecache.clear();
 		autoid_counter = 0;

backends/smt2/smt2.cc

@@ -1744,6 +1744,7 @@ struct Smt2Backend : public Backend {
 		log_push();
 		Pass::call(design, "bmuxmap");
 		Pass::call(design, "demuxmap");
+		Pass::call(design, "bwmuxmap");
 		log_pop();
 
 		size_t argidx;

backends/smv/smv.cc

@@ -744,6 +744,7 @@ struct SmvBackend : public Backend {
 		log_push();
 		Pass::call(design, "bmuxmap");
 		Pass::call(design, "demuxmap");
+		Pass::call(design, "bwmuxmap");
 		log_pop();
 
 		size_t argidx;

backends/verilog/verilog_backend.cc

@@ -2329,6 +2329,7 @@ struct VerilogBackend : public Backend {
 		if (!noexpr) {
 			Pass::call(design, "bmuxmap");
 			Pass::call(design, "demuxmap");
+			Pass::call(design, "bwmuxmap");
 		}
 		Pass::call(design, "clean_zerowidth");
 		log_pop();

passes/techmap/Makefile.inc

@@ -31,6 +31,7 @@ OBJS += passes/techmap/dffinit.o
 OBJS += passes/techmap/pmuxtree.o
 OBJS += passes/techmap/bmuxmap.o
 OBJS += passes/techmap/demuxmap.o
+OBJS += passes/techmap/bwmuxmap.o
 OBJS += passes/techmap/muxcover.o
 OBJS += passes/techmap/aigmap.o
 OBJS += passes/techmap/tribuf.o

passes/techmap/bwmuxmap.cc

@@ -0,0 +1,70 @@
+/*
+ *  yosys -- Yosys Open SYnthesis Suite
+ *
+ *  Copyright (C) 2022  Jannis Harder <jix@yosyshq.com> <me@jix.one>
+ *
+ *  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 BwmuxmapPass : public Pass {
+	BwmuxmapPass() : Pass("bwmuxmap", "replace $bwmux cells with equivalent logic") {}
+	void help() override
+	{
+		//   |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
+		log("\n");
+		log("    bwmxumap [options] [selection]\n");
+		log("\n");
+		log("This pass replaces $bwmux cells with equivalent logic\n");
+		log("\n");
+	}
+	void execute(std::vector<std::string> args, RTLIL::Design *design) override
+	{
+		log_header(design, "Executing BWMUXMAP pass.\n");
+
+		size_t argidx;
+		for (argidx = 1; argidx < args.size(); argidx++) {
+			// if (args[argidx] == "-arg") {
+			// 	continue;
+			// }
+			break;
+		}
+
+		extra_args(args, argidx, design);
+
+		for (auto module : design->selected_modules())
+		for (auto cell : module->selected_cells())
+		{
+			if (cell->type != ID($bwmux))
+				continue;
+			auto &sig_y = cell->getPort(ID::Y);
+			auto &sig_a = cell->getPort(ID::A);
+			auto &sig_b = cell->getPort(ID::B);
+			auto &sig_s = cell->getPort(ID::S);
+
+			auto not_s = module->Not(NEW_ID, sig_s);
+			auto masked_b = module->And(NEW_ID, sig_s, sig_b);
+			auto masked_a = module->And(NEW_ID, not_s, sig_a);
+			module->addOr(NEW_ID, masked_a, masked_b, sig_y);
+
+			module->remove(cell);
+		}
+	}
+} BwmuxmapPass;
+
+PRIVATE_NAMESPACE_END