From 302edf04291467469f8f48bd60edadbf1ee54798 Mon Sep 17 00:00:00 2001
From: tklam <tklam@easylogic.hk>
Date: Sat, 13 Oct 2018 23:11:19 +0800
Subject: [PATCH] stop check_signal_in_fanout from traversing FFs

---
 passes/equiv/equiv_make.cc | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/passes/equiv/equiv_make.cc b/passes/equiv/equiv_make.cc
index e74dab36f..e75482e9f 100644
--- a/passes/equiv/equiv_make.cc
+++ b/passes/equiv/equiv_make.cc
@@ -42,6 +42,14 @@ struct EquivMakeWorker
 
 	dict<SigBit, pool<Cell*>> bit2driven; // map: bit <--> and its driven cells
 
+	CellTypes comb_ct;
+
+	EquivMakeWorker()
+	{
+		comb_ct.setup_internals();
+		comb_ct.setup_stdcells();
+	}
+
 	void read_blacklists()
 	{
 		for (auto fn : blacklists)
@@ -415,9 +423,12 @@ struct EquivMakeWorker
 		auto driven_cells = bit2driven.at(source_bit);
 		for (auto driven_cell: driven_cells)
 		{
-			if (visited_cells.count(driven_cell) > 0)
+			bool is_comb = comb_ct.cell_known(cell->type);
+			if (is_comb)
 				continue;
 
+			if (visited_cells.count(driven_cell) > 0)
+				continue;
 			visited_cells.insert(driven_cell);
 
 			for (auto &conn: driven_cell->connections())