From 93a24fe275509c5a69f3fc94b29306afe3593cf1 Mon Sep 17 00:00:00 2001
From: Akash Levy <akash@silimate.com>
Date: Mon, 29 Sep 2025 20:56:58 -0700
Subject: [PATCH] Put back is_mostly_const

---
 kernel/rtlil.cc | 12 ++++++++++++
 kernel/rtlil.h  |  3 ++-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/kernel/rtlil.cc b/kernel/rtlil.cc
index c5ecf1573..1be54dca1 100644
--- a/kernel/rtlil.cc
+++ b/kernel/rtlil.cc
@@ -5437,6 +5437,18 @@ bool RTLIL::SigSpec::is_chunk() const
 	return GetSize(chunks_) == 1;
 }
 
+bool RTLIL::SigSpec::is_mostly_const() const
+{
+	cover("kernel.rtlil.sigspec.is_mostly_const");
+
+	pack();
+	int constbits = 0;
+	for (auto it = chunks_.begin(); it != chunks_.end(); it++)
+		if (it->width > 0 && it->wire == NULL)
+			constbits += it->width;
+	return (constbits > width_/2);
+}
+
 bool RTLIL::SigSpec::known_driver() const
 {
 	pack();
diff --git a/kernel/rtlil.h b/kernel/rtlil.h
index d12a33080..a9d2accdf 100644
--- a/kernel/rtlil.h
+++ b/kernel/rtlil.h
@@ -1347,7 +1347,8 @@ public:
 	inline bool is_bit() const { return width_ == 1; }
 
 	bool known_driver() const;
-
+	
+	bool is_mostly_const() const;
 	bool is_fully_const() const;
 	bool is_fully_zero() const;
 	bool is_fully_ones() const;