Add dffunmap pass.

To be used with backends that cannot deal with fancy FF types (like blif
or smt).

2 files changed, 108 insertions, 0 deletions

diff --git a/passes/techmap/Makefile.inc b/passes/techmap/Makefile.inc
index e3b3d8dea..5a4d84f94 100644
--- a/passes/techmap/Makefile.inc
+++ b/passes/techmap/Makefile.inc
@@ -43,6 +43,7 @@ OBJS += passes/techmap/attrmap.o
 OBJS += passes/techmap/zinit.o
 OBJS += passes/techmap/dfflegalize.o
 OBJS += passes/techmap/dff2dffs.o
+OBJS += passes/techmap/dffunmap.o
 OBJS += passes/techmap/flowmap.o
 OBJS += passes/techmap/extractinv.o
 endif
diff --git a/passes/techmap/dffunmap.cc b/passes/techmap/dffunmap.cc
new file mode 100644
index 000000000..fb107ff75
--- /dev/null
+++ b/passes/techmap/dffunmap.cc
@@ -0,0 +1,107 @@
+/*
+ *  yosys -- Yosys Open SYnthesis Suite
+ *
+ *  Copyright (C) 2020  Marcelina Kościelnicka <mwk@0x04.net>
+ *
+ *  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"
+#include "kernel/sigtools.h"
+#include "kernel/ff.h"
+
+USING_YOSYS_NAMESPACE
+PRIVATE_NAMESPACE_BEGIN
+
+struct DffunmapPass : public Pass {
+	DffunmapPass() : Pass("dffunmap", "unmap clock enable and synchronous reset from FFs") { }
+	void help() override
+	{
+		//   |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
+		log("\n");
+		log("    dffunmap [options] [selection]\n");
+		log("\n");
+		log("This pass transforms FF types with clock enable and/or synchronous reset into\n");
+		log("their base type (with neither clock enable nor sync reset) by emulating the clock\n");
+		log("enable and synchronous reset with multiplexers on the cell input.\n");
+		log("\n");
+		log("    -ce-only\n");
+		log("        unmap only clock enables, leave synchronous resets alone.\n");
+		log("\n");
+		log("    -srst-only\n");
+		log("        unmap only synchronous resets, leave clock enables alone.\n");
+		log("\n");
+	}
+	void execute(std::vector<std::string> args, RTLIL::Design *design) override
+	{
+		log_header(design, "Executing DFFUNMAP pass (unmap clock enable and synchronous reset from FFs).\n");
+
+		bool ce_only = false;
+		bool srst_only = false;
+
+		size_t argidx;
+		for (argidx = 1; argidx < args.size(); argidx++) {
+			if (args[argidx] == "-ce-only") {
+				ce_only = true;
+				continue;
+			}
+			if (args[argidx] == "-srst-only") {
+				srst_only = true;
+				continue;
+			}
+			break;
+		}
+		extra_args(args, argidx, design);
+
+		if (ce_only && srst_only)
+			log_cmd_error("Options -ce-only and -srst-only are mutually exclusive!\n");
+
+		for (auto mod : design->selected_modules())
+		{
+			SigMap sigmap(mod);
+			FfInitVals initvals(&sigmap, mod);
+
+			for (auto cell : mod->selected_cells())
+			{
+				if (!RTLIL::builtin_ff_cell_types().count(cell->type))
+					continue;
+
+				FfData ff(&initvals, cell);
+				IdString name = cell->name;
+
+				if (!ff.has_clk)
+					continue;
+
+				if (ce_only) {
+					if (!ff.has_en)
+						continue;
+					ff.unmap_ce(mod);
+				} else if (srst_only) {
+					if (!ff.has_srst)
+						continue;
+					ff.unmap_srst(mod);
+				} else {
+					if (!ff.has_en && !ff.has_srst)
+						continue;
+					ff.unmap_ce_srst(mod);
+				}
+
+				mod->remove(cell);
+				ff.emit(mod, name);
+			}
+		}
+	}
+} DffunmapPass;
+
+PRIVATE_NAMESPACE_END