From c4b8575f4322f72dd1b35e2737966db731a26c17 Mon Sep 17 00:00:00 2001
From: Clifford Wolf <clifford@clifford.at>
Date: Mon, 20 May 2019 15:36:13 +0200
Subject: [PATCH] Add "wreduce -keepdc", fixes #1016

Signed-off-by: Clifford Wolf <clifford@clifford.at>
---
 passes/opt/wreduce.cc   | 10 +++++++++-
 techlibs/common/prep.cc |  6 ++++--
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/passes/opt/wreduce.cc b/passes/opt/wreduce.cc
index 58c6e4b4b..1fbc41082 100644
--- a/passes/opt/wreduce.cc
+++ b/passes/opt/wreduce.cc
@@ -29,6 +29,7 @@ PRIVATE_NAMESPACE_BEGIN
 struct WreduceConfig
 {
 	pool<IdString> supported_cell_types;
+	bool keepdc = false;
 
 	WreduceConfig()
 	{
@@ -82,7 +83,7 @@ struct WreduceWorker
 
 			SigBit ref = sig_a[i];
 			for (int k = 0; k < GetSize(sig_s); k++) {
-				if (ref != Sx && sig_b[k*GetSize(sig_a) + i] != Sx && ref != sig_b[k*GetSize(sig_a) + i])
+				if ((config->keepdc || (ref != Sx && sig_b[k*GetSize(sig_a) + i] != Sx)) && ref != sig_b[k*GetSize(sig_a) + i])
 					goto no_match_ab;
 				if (sig_b[k*GetSize(sig_a) + i] != Sx)
 					ref = sig_b[k*GetSize(sig_a) + i];
@@ -495,6 +496,9 @@ struct WreducePass : public Pass {
 		log("        Do not change the width of memory address ports. Use this options in\n");
 		log("        flows that use the 'memory_memx' pass.\n");
 		log("\n");
+		log("    -keepdc\n");
+		log("        Do not optimize explicit don't-care values.\n");
+		log("\n");
 	}
 	void execute(std::vector<std::string> args, Design *design) YS_OVERRIDE
 	{
@@ -509,6 +513,10 @@ struct WreducePass : public Pass {
 				opt_memx = true;
 				continue;
 			}
+			if (args[argidx] == "-keepdc") {
+				config.keepdc = true;
+				continue;
+			}
 			break;
 		}
 		extra_args(args, argidx, design);
diff --git a/techlibs/common/prep.cc b/techlibs/common/prep.cc
index 86fb4d6c6..cdd21c3b3 100644
--- a/techlibs/common/prep.cc
+++ b/techlibs/common/prep.cc
@@ -195,9 +195,11 @@ struct PrepPass : public ScriptPass
 			run(nokeepdc ? "opt" : "opt -keepdc");
 			if (!ifxmode) {
 				if (help_mode)
-					run("wreduce [-memx]");
-				else
+					run("wreduce -keepdc [-memx]");
+				else if (nokeepdc)
 					run(memxmode ? "wreduce -memx" : "wreduce");
+				else
+					run(memxmode ? "wreduce -keepdc -memx" : "wreduce -keepdc");
 			}
 			if (!nomemmode) {
 				run(string("memory_dff") + (help_mode ? " [-nordff]" : nordff ? " -nordff" : ""));
-- 
2.30.2