From 1764c0ee3c6db3cdc07f78dbdc3d24d3a9cf61a5 Mon Sep 17 00:00:00 2001
From: Miodrag Milanovic <mmicko@gmail.com>
Date: Thu, 18 Jan 2024 08:47:04 +0100
Subject: [PATCH] Fix verific clocking when no driver exist

---
 frontends/verific/verific.cc |  2 +-
 tests/verific/clocking.ys    | 10 ++++++++++
 2 files changed, 11 insertions(+), 1 deletion(-)
 create mode 100644 tests/verific/clocking.ys

diff --git a/frontends/verific/verific.cc b/frontends/verific/verific.cc
index 9737fde89..adabd2700 100644
--- a/frontends/verific/verific.cc
+++ b/frontends/verific/verific.cc
@@ -2110,7 +2110,7 @@ VerificClocking::VerificClocking(VerificImporter *importer, Net *net, bool sva_a
 	if (sva_at_only)
 	do {
 		Instance *inst_mux = net->Driver();
-		if (inst_mux->Type() != PRIM_MUX)
+		if (inst_mux == nullptr || inst_mux->Type() != PRIM_MUX)
 			break;
 
 		bool pwr1 = inst_mux->GetInput1()->IsPwr();
diff --git a/tests/verific/clocking.ys b/tests/verific/clocking.ys
new file mode 100644
index 000000000..bfdbeb748
--- /dev/null
+++ b/tests/verific/clocking.ys
@@ -0,0 +1,10 @@
+read -sv <<EOT
+module test(input foo);
+always @(*) assert(foo);
+endmodule
+EOT
+
+verific -import test
+prep
+
+select -assert-count 1 t:$assert