From 1d83854d84b7a0a23ee14b72c1a289b50becdeca Mon Sep 17 00:00:00 2001
From: Clifford Wolf <clifford@clifford.at>
Date: Thu, 15 Oct 2015 14:57:28 +0200
Subject: [PATCH] Bugfixes in handling of "keep" attribute on wires

---
 passes/opt/opt_muxtree.cc | 2 +-
 passes/opt/wreduce.cc     | 8 +++++++-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/passes/opt/opt_muxtree.cc b/passes/opt/opt_muxtree.cc
index 15d59202e..905a01627 100644
--- a/passes/opt/opt_muxtree.cc
+++ b/passes/opt/opt_muxtree.cc
@@ -136,7 +136,7 @@ struct OptMuxtreeWorker
 			}
 		}
 		for (auto wire : module->wires()) {
-			if (wire->port_output)
+			if (wire->port_output || wire->get_bool_attribute("\\keep"))
 				for (int idx : sig2bits(RTLIL::SigSpec(wire)))
 					bit2info[idx].seen_non_mux = true;
 		}
diff --git a/passes/opt/wreduce.cc b/passes/opt/wreduce.cc
index e551443ff..c194d428d 100644
--- a/passes/opt/wreduce.cc
+++ b/passes/opt/wreduce.cc
@@ -51,6 +51,7 @@ struct WreduceWorker
 
 	std::set<Cell*, IdString::compare_ptr_by_name<Cell>> work_queue_cells;
 	std::set<SigBit> work_queue_bits;
+	pool<SigBit> keep_bits;
 
 	WreduceWorker(WreduceConfig *config, Module *module) :
 			config(config), module(module), mi(module) { }
@@ -68,7 +69,7 @@ struct WreduceWorker
 		for (int i = GetSize(sig_y)-1; i >= 0; i--)
 		{
 			auto info = mi.query(sig_y[i]);
-			if (!info->is_output && GetSize(info->ports) <= 1) {
+			if (!info->is_output && GetSize(info->ports) <= 1 && !keep_bits.count(mi.sigmap(sig_y[i]))) {
 				bits_removed.push_back(Sx);
 				continue;
 			}
@@ -265,6 +266,11 @@ struct WreduceWorker
 
 	void run()
 	{
+		for (auto w : module->wires())
+			if (w->get_bool_attribute("\\keep"))
+				for (auto bit : mi.sigmap(w))
+					keep_bits.insert(bit);
+
 		for (auto c : module->selected_cells())
 			work_queue_cells.insert(c);
 
-- 
2.30.2