From: Marcelina Kościelnicka <mwk@0x04.net>
Date: Tue, 7 Jun 2022 02:26:25 +0000 (+0200)
Subject: opt_ffinv: Harden against simple ff/inv loop.
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=d07828b40958c6c2a1d09cf13c9a307c75b855b4;p=yosys.git

opt_ffinv: Harden against simple ff/inv loop.
---

diff --git a/passes/opt/opt_ffinv.cc b/passes/opt/opt_ffinv.cc
index fd76dd2be..fe5b59fa5 100644
--- a/passes/opt/opt_ffinv.cc
+++ b/passes/opt/opt_ffinv.cc
@@ -72,6 +72,8 @@ struct OptFfInvWorker
 		for (auto &port: q_ports) {
 			if (port.cell == ff.cell && port.port == ID::Q)
 				continue;
+			if (port.cell == d_inv)
+				return false;
 			if (port.port != ID::A)
 				return false;
 			if (!port.cell->type.in(ID($not), ID($_NOT_), ID($lut)))
@@ -148,6 +150,8 @@ struct OptFfInvWorker
 		for (auto &port: q_ports) {
 			if (port.cell == ff.cell && port.port == ID::Q)
 				continue;
+			if (port.cell == d_lut)
+				return false;
 			if (port.port != ID::A)
 				return false;
 			if (port.cell->type.in(ID($not), ID($_NOT_))) {