From 8d821dbbdb3ba68d4cd0fdb0d5857e77725275b9 Mon Sep 17 00:00:00 2001
From: whitequark <whitequark@whitequark.org>
Date: Mon, 8 Jun 2020 19:18:11 +0000
Subject: [PATCH] flatten: only prepend $flatten once per wire.

---
 passes/techmap/flatten.cc | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/passes/techmap/flatten.cc b/passes/techmap/flatten.cc
index 669159167..e913b3059 100644
--- a/passes/techmap/flatten.cc
+++ b/passes/techmap/flatten.cc
@@ -32,8 +32,12 @@ IdString concat_name(RTLIL::Cell *cell, IdString object_name)
 {
 	if (object_name[0] == '\\')
 		return stringf("%s.%s", cell->name.c_str(), object_name.c_str() + 1);
-	else
-		return stringf("$flatten%s.%s", cell->name.c_str(), object_name.c_str());
+	else {
+		std::string object_name_str = object_name.str();
+		if (object_name_str.substr(0, 8) == "$flatten")
+			object_name_str.erase(0, 8);
+		return stringf("$flatten%s.%s", cell->name.c_str(), object_name_str.c_str());
+	}
 }
 
 template<class T>
-- 
2.30.2