From c68722818a09ce541c380178ff17e548db9c897d Mon Sep 17 00:00:00 2001
From: whitequark <whitequark@whitequark.org>
Date: Tue, 12 Nov 2019 00:15:43 +0000
Subject: [PATCH] =?utf8?q?flowmap:=20when=20doing=20mincut,=20ensure=20sou?=
 =?utf8?q?rce=20is=20always=20in=20X,=20not=20X=CC=85.?=
MIME-Version: 1.0
Content-Type: text/plain; charset=utf8
Content-Transfer-Encoding: 8bit

Fixes #1475.
---
 passes/techmap/flowmap.cc | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/passes/techmap/flowmap.cc b/passes/techmap/flowmap.cc
index 96eee45db..a2ad87f7d 100644
--- a/passes/techmap/flowmap.cc
+++ b/passes/techmap/flowmap.cc
@@ -394,7 +394,7 @@ struct FlowGraph
 
 	pair<pool<RTLIL::SigBit>, pool<RTLIL::SigBit>> edge_cut()
 	{
-		pool<RTLIL::SigBit> x, xi;
+		pool<RTLIL::SigBit> x = {source}, xi; // X and X̅ in the paper
 
 		NodePrime source_prime = {source, true};
 		pool<NodePrime> visited;
@@ -437,6 +437,7 @@ struct FlowGraph
 		for (auto collapsed_node : collapsed[sink])
 			xi.insert(collapsed_node);
 
+		log_assert(x[source] && !xi[source]);
 		log_assert(!x[sink] && xi[sink]);
 		return {x, xi};
 	}
-- 
2.30.2