From 9cba05285b14ffb3433e2e9d9e44b755311562f5 Mon Sep 17 00:00:00 2001
From: Eddie Hung <eddie@fpgeh.com>
Date: Wed, 26 Jun 2019 16:06:30 -0700
Subject: [PATCH] muxcover to be undef-sensitive when computing decoders

---
 passes/techmap/muxcover.cc | 63 +++++++++++++++++++++++++-------------
 1 file changed, 41 insertions(+), 22 deletions(-)

diff --git a/passes/techmap/muxcover.cc b/passes/techmap/muxcover.cc
index b0722134e..61471e446 100644
--- a/passes/techmap/muxcover.cc
+++ b/passes/techmap/muxcover.cc
@@ -151,7 +151,7 @@ struct MuxcoverWorker
 				return true;
 			}
 			char port_name[3] = {'\\', *path, 0};
-			return follow_muxtree(ret_bit, tree, sigmap(tree.muxes.at(bit)->getPort(port_name)), path+1, false);
+			return follow_muxtree(ret_bit, tree, tree.muxes.at(bit)->getPort(port_name), path+1, false);
 		} else {
 			ret_bit = bit;
 			return true;
@@ -160,7 +160,7 @@ struct MuxcoverWorker
 
 	int prepare_decode_mux(SigBit &A, SigBit B, SigBit sel, SigBit bit)
 	{
-		if (A == B || sel == State::Sx)
+		if (A == B || sel == State::Sx || A == State::Sx || B == State::Sx)
 			return 0;
 
 		tuple<SigBit, SigBit, SigBit> key(A, B, sel);
@@ -330,13 +330,15 @@ struct MuxcoverWorker
 			ok = ok && follow_muxtree(S4, tree, bit, "BBS");
 
 			if (nodecode)
-				ok = ok && S1 == S2 && S2 == S3 && S3 == S4;
+				ok = ok && (S1 == S2 || S1 == State::Sx || S2 == State::Sx) &&
+					/*S2 == S3 && */
+					(S3 == S4 || S3 == State::Sx || S4 == State::Sx);
 
 			ok = ok && follow_muxtree(T1, tree, bit, "AS");
 			ok = ok && follow_muxtree(T2, tree, bit, "BS");
 
 			if (nodecode)
-				ok = ok && T1 == T2;
+				ok = ok && (T1 == T2 || T1 == State::Sx || T2 == State::Sx);
 
 			ok = ok && follow_muxtree(U1, tree, bit, "S");
 
@@ -353,11 +355,12 @@ struct MuxcoverWorker
 				mux.inputs.push_back(G);
 				mux.inputs.push_back(H);
 
+				mux.cost += prepare_decode_mux(T1, T2, U1, bit);
+
 				mux.cost += prepare_decode_mux(S1, S2, T1, bit);
 				mux.cost += prepare_decode_mux(S3, S4, T2, bit);
-				mux.cost += prepare_decode_mux(S1, S3, U1, bit);
-
-				mux.cost += prepare_decode_mux(T1, T2, U1, bit);
+				if (T1 != T2 && T1 != State::Sx && T2 != State::Sx)
+					mux.cost += prepare_decode_mux(S1, S3, U1, bit);
 
 				mux.selects.push_back(S1);
 				mux.selects.push_back(T1);
@@ -407,7 +410,13 @@ struct MuxcoverWorker
 			ok = ok && follow_muxtree(S8, tree, bit, "BBBS");
 
 			if (nodecode)
-				ok = ok && S1 == S2 && S2 == S3 && S3 == S4 && S4 == S5 && S5 == S6 && S6 == S7 && S7 == S8;
+				ok = ok && (S1 == S2 || S1 == State::Sx || S2 == State::Sx) &&
+					/*S2 == S3 &&*/
+					(S3 == S4 || S3 == State::Sx || S4 == State::Sx) &&
+					/*S4 == S5 &&*/
+					(S5 == S6 || S5 == State::Sx || S6 == State::Sx) &&
+					/*S6 == S7 &&*/
+					(S7 == S8 || S7 == State::Sx || S8 == State::Sx);
 
 			ok = ok && follow_muxtree(T1, tree, bit, "AAS");
 			ok = ok && follow_muxtree(T2, tree, bit, "ABS");
@@ -415,13 +424,15 @@ struct MuxcoverWorker
 			ok = ok && follow_muxtree(T4, tree, bit, "BBS");
 
 			if (nodecode)
-				ok = ok && T1 == T2 && T2 == T3 && T3 == T4;
+				ok = ok && (T1 == T2 || T1 == State::Sx || T2 == State::Sx) &&
+					/*T2 == T3 &&*/
+					(T3 == T4 || T3 == State::Sx || T4 == State::Sx);
 
 			ok = ok && follow_muxtree(U1, tree, bit, "AS");
 			ok = ok && follow_muxtree(U2, tree, bit, "BS");
 
 			if (nodecode)
-				ok = ok && U1 == U2;
+				ok = ok && (U1 == U2 || U1 == State::Sx || U2 == State::Sx);
 
 			ok = ok && follow_muxtree(V1, tree, bit, "S");
 
@@ -446,20 +457,28 @@ struct MuxcoverWorker
 				mux.inputs.push_back(O);
 				mux.inputs.push_back(P);
 
-				mux.cost += prepare_decode_mux(S1, S2, T1, bit);
-				mux.cost += prepare_decode_mux(S3, S4, T2, bit);
-				mux.cost += prepare_decode_mux(S5, S6, T3, bit);
-				mux.cost += prepare_decode_mux(S7, S8, T4, bit);
-				mux.cost += prepare_decode_mux(S1, S3, U1, bit);
-				mux.cost += prepare_decode_mux(S5, S7, U2, bit);
-				mux.cost += prepare_decode_mux(S1, S5, V1, bit);
-
-				mux.cost += prepare_decode_mux(T1, T2, U1, bit);
-				mux.cost += prepare_decode_mux(T3, T4, U2, bit);
-				mux.cost += prepare_decode_mux(T1, T3, V1, bit);
-
 				mux.cost += prepare_decode_mux(U1, U2, V1, bit);
 
+				if (U1 != State::Sx && U2 != State::Sx) {
+					mux.cost += prepare_decode_mux(T1, T2, U1, bit);
+					mux.cost += prepare_decode_mux(T3, T4, U2, bit);
+					mux.cost += prepare_decode_mux(T1, T3, V1, bit);
+				}
+
+				if (T1 != T2 && T1 != State::Sx && T2 != State::Sx) {
+					mux.cost += prepare_decode_mux(S1, S2, T1, bit);
+					mux.cost += prepare_decode_mux(S3, S4, T2, bit);
+					mux.cost += prepare_decode_mux(S1, S3, U1, bit);
+				}
+				if (T3 != T4 && T3 != State::Sx && T4 != State::Sx) {
+					mux.cost += prepare_decode_mux(S5, S6, T3, bit);
+					mux.cost += prepare_decode_mux(S7, S8, T4, bit);
+					mux.cost += prepare_decode_mux(S5, S7, U2, bit);
+				}
+				if (T1 != T2 && T1 != State::Sx && T2 != State::Sx &&
+						T3 != T4 && T3 != State::Sx && T4 != State::Sx)
+					mux.cost += prepare_decode_mux(S1, S5, V1, bit);
+
 				mux.selects.push_back(S1);
 				mux.selects.push_back(T1);
 				mux.selects.push_back(U1);