From cb9bfed1699bd5c1ee0eed475e501c56383f62e7 Mon Sep 17 00:00:00 2001
From: nella <simontupy64@gmail.com>
Date: Thu, 25 Jun 2026 11:14:46 +0200
Subject: [PATCH] Tighten sig2bits.

---
 kernel/bitpattern.h | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/kernel/bitpattern.h b/kernel/bitpattern.h
index e2071436c..76c008b89 100644
--- a/kernel/bitpattern.h
+++ b/kernel/bitpattern.h
@@ -102,11 +102,19 @@ struct BitPatternPool
 		bits_t bits;
 		bits.bitdata = sig.as_const().to_bits();
 		for (auto &b : bits.bitdata)
-			if (b > RTLIL::State::S1)
+			if (b > RTLIL::State::S1 && b != RTLIL::State::Sx && b != RTLIL::State::Sz)
 				b = RTLIL::State::Sa;
 		return bits;
 	}
 
+	static bool covers_nothing(const bits_t &bits)
+	{
+		for (auto &b : bits.bitdata)
+			if (b == RTLIL::State::Sx || b == RTLIL::State::Sz)
+				return true;
+		return false;
+	}
+
 	/**
 	 * Two cubes match if their intersection is non-empty.
 	 */
@@ -132,6 +140,8 @@ struct BitPatternPool
 	bool has_any(RTLIL::SigSpec sig)
 	{
 		bits_t bits = sig2bits(sig);
+		if (covers_nothing(bits))
+			return false;
 		for (auto &it : database)
 			if (match(it, bits))
 				return true;
@@ -150,6 +160,8 @@ struct BitPatternPool
 	bool has_all(RTLIL::SigSpec sig)
 	{
 		bits_t bits = sig2bits(sig);
+		if (covers_nothing(bits))
+			return true;
 		for (auto &it : database)
 			if (match(it, bits)) {
 				for (int i = 0; i < width; i++)
@@ -171,6 +183,8 @@ struct BitPatternPool
 	{
 		bool status = false;
 		bits_t bits = sig2bits(sig);
+		if (covers_nothing(bits))
+			return false;
 		for (auto it = database.begin(); it != database.end();)
 			if (match(*it, bits)) {
 				for (int i = 0; i < width; i++) {