From 16a92707fb1ff725fba82c993bf93728227e0f34 Mon Sep 17 00:00:00 2001
From: Akash Levy <akash@silimate.com>
Date: Sun, 16 Nov 2025 18:34:37 -0500
Subject: [PATCH] Fix `isBuffer` (#329)

* Add support for "well" direction type (nwell, pwell, etc.), and fix isBuffer (+ other functions) to accommodate wells

* Just fix isBuffer issue
---
 liberty/Liberty.cc       |  3 ++-
 test/get_is_buffer.ok    |  1 +
 test/get_is_buffer.tcl   |  5 +++++
 test/get_is_buffer.v     | 11 +++++++++++
 test/regression_vars.tcl |  1 +
 5 files changed, 20 insertions(+), 1 deletion(-)
 create mode 100644 test/get_is_buffer.ok
 create mode 100644 test/get_is_buffer.tcl
 create mode 100644 test/get_is_buffer.v

diff --git a/liberty/Liberty.cc b/liberty/Liberty.cc
index c4d9fdd3..3cf867f2 100644
--- a/liberty/Liberty.cc
+++ b/liberty/Liberty.cc
@@ -1226,7 +1226,8 @@ LibertyCell::bufferPorts(// Return values.
       }
       output = port;
     }
-    else if (!dir->isPowerGround()) {
+    else if (!port->isPwrGnd()) {
+        // Invalid direction.
 	input = nullptr;
 	output = nullptr;
 	break;
diff --git a/test/get_is_buffer.ok b/test/get_is_buffer.ok
new file mode 100644
index 00000000..655d42ed
--- /dev/null
+++ b/test/get_is_buffer.ok
@@ -0,0 +1 @@
+buf_inst
diff --git a/test/get_is_buffer.tcl b/test/get_is_buffer.tcl
new file mode 100644
index 00000000..c02f682e
--- /dev/null
+++ b/test/get_is_buffer.tcl
@@ -0,0 +1,5 @@
+# is_buffer property
+read_liberty ../examples/sky130hd_tt.lib.gz
+read_verilog get_is_buffer.v
+link_design dut
+report_object_full_names [get_cells -filter is_buffer]
diff --git a/test/get_is_buffer.v b/test/get_is_buffer.v
new file mode 100644
index 00000000..91f8afea
--- /dev/null
+++ b/test/get_is_buffer.v
@@ -0,0 +1,11 @@
+module dut (
+	input           A,
+	output          Y
+);
+
+	sky130_fd_sc_hd__buf_2 buf_inst (
+		.A(A),
+		.X(Y)
+	);
+
+endmodule
diff --git a/test/regression_vars.tcl b/test/regression_vars.tcl
index c8e662e7..f3eb42e9 100644
--- a/test/regression_vars.tcl
+++ b/test/regression_vars.tcl
@@ -140,6 +140,7 @@ record_example_tests {
 record_sta_tests {
   disconnect_mcp_pin
   get_filter
+  get_is_buffer
   get_is_memory
   get_lib_pins_of_objects
   get_noargs