From eb96123030b253590009e56784876bd5b0da752d Mon Sep 17 00:00:00 2001
From: "Emil J. Tywoniak" <emil@tywoniak.eu>
Date: Tue, 14 Jul 2026 18:02:02 +0200
Subject: [PATCH] dfflibmap: add regression test for resetval clobber

---
 tests/techmap/dfflibmap_resetval_clobber.lib | 52 ++++++++++++++++++++
 tests/techmap/dfflibmap_resetval_clobber.ys  | 13 +++++
 2 files changed, 65 insertions(+)
 create mode 100644 tests/techmap/dfflibmap_resetval_clobber.lib
 create mode 100644 tests/techmap/dfflibmap_resetval_clobber.ys

diff --git a/tests/techmap/dfflibmap_resetval_clobber.lib b/tests/techmap/dfflibmap_resetval_clobber.lib
new file mode 100644
index 000000000..dcf4e4402
--- /dev/null
+++ b/tests/techmap/dfflibmap_resetval_clobber.lib
@@ -0,0 +1,52 @@
+library(test) {
+  cell (bad_dff) {
+    area : 1;
+    ff("IQ", "IQN") {
+      next_state : "!D"; // Look here
+      clocked_on : "CLK";
+      preset     : "!RST"; // Look here
+    }
+    pin(D) {
+      direction : input;
+    }
+    pin(CLK) {
+      direction : input;
+    }
+    pin(RST) {
+      direction : input;
+    }
+    pin(Q) {
+      direction: output;
+      function : "IQ";
+    }
+    pin(QN) {
+      direction: output;
+      function : "IQN";
+    }
+  }
+  cell (good_dff) {
+    area : 1;
+    ff("IQ", "IQN") {
+      next_state : "D"; // Look here
+      clocked_on : "CLK";
+      clear      : "RST"; // Look here
+    }
+    pin(D) {
+      direction : input;
+    }
+    pin(CLK) {
+      direction : input;
+    }
+    pin(RST) {
+      direction : input;
+    }
+    pin(Q) {
+      direction: output;
+      function : "IQ";
+    }
+    pin(QN) {
+      direction: output;
+      function : "IQN";
+    }
+  }
+}
diff --git a/tests/techmap/dfflibmap_resetval_clobber.ys b/tests/techmap/dfflibmap_resetval_clobber.ys
new file mode 100644
index 000000000..aacf40f6c
--- /dev/null
+++ b/tests/techmap/dfflibmap_resetval_clobber.ys
@@ -0,0 +1,13 @@
+read_verilog -icells <<EOT
+module top(input C, D, R, output Q);
+$_DFF_PP0_ ff (.C(C), .D(D), .R(R), .Q(Q));
+endmodule
+EOT
+
+dfflibmap -liberty dfflibmap_resetval_clobber.lib top
+read_liberty dfflibmap_resetval_clobber.lib
+flatten -noscopeinfo
+opt_clean
+
+select -assert-count 1 t:* top %i
+select -assert-count 1 t:$_DFF_PP0_ top %i
\ No newline at end of file