From 46d2446f88904a2a4c47ddb814fa1950cb89b726 Mon Sep 17 00:00:00 2001
From: James Cherry <cherry@parallaxsw.com>
Date: Thu, 9 Jul 2020 08:42:52 -0700
Subject: [PATCH] LibertyCell::isInverter

---
 include/sta/Liberty.hh |  3 +++
 liberty/Liberty.cc     | 21 +++++++++++++++++++++
 search/Property.cc     |  2 ++
 3 files changed, 26 insertions(+)

diff --git a/include/sta/Liberty.hh b/include/sta/Liberty.hh
index 5818e4bb..c7f374b4 100644
--- a/include/sta/Liberty.hh
+++ b/include/sta/Liberty.hh
@@ -493,6 +493,7 @@ public:
 	      Report *report,
 	      Debug *debug);
   bool isBuffer() const;
+  bool isInverter() const;
   // Only valid when isBuffer() returns true.
   void bufferPorts(// Return values.
 		   LibertyPort *&input,
@@ -522,6 +523,8 @@ protected:
   void makeTimingArcPortMaps();
   bool hasBufferFunc(const LibertyPort *input,
 		     const LibertyPort *output) const;
+  bool hasInverterFunc(const LibertyPort *input,
+		       const LibertyPort *output) const;
 
   LibertyLibrary *liberty_library_;
   float area_;
diff --git a/liberty/Liberty.cc b/liberty/Liberty.cc
index 38a64706..efb7919d 100644
--- a/liberty/Liberty.cc
+++ b/liberty/Liberty.cc
@@ -1064,6 +1064,27 @@ LibertyCell::hasBufferFunc(const LibertyPort *input,
     && func->port() == input;
 }
 
+bool
+LibertyCell::isInverter() const
+{
+  LibertyPort *input;
+  LibertyPort *output;
+  bufferPorts(input, output);
+  return input && output
+    && hasInverterFunc(input, output);
+}
+
+bool
+LibertyCell::hasInverterFunc(const LibertyPort *input,
+			     const LibertyPort *output) const
+{
+  FuncExpr *func = output->function();
+  return func
+    && func->op() == FuncExpr::op_not
+    && func->left()->op() == FuncExpr::op_port
+    && func->left()->port() == input;
+}
+
 void
 LibertyCell::bufferPorts(// Return values.
 			 LibertyPort *&input,
diff --git a/search/Property.cc b/search/Property.cc
index 0a840dfa..d69bd3f1 100644
--- a/search/Property.cc
+++ b/search/Property.cc
@@ -566,6 +566,8 @@ getProperty(const LibertyCell *cell,
     return PropertyValue(cell->libertyLibrary());
   else if (stringEqual(property, "is_buffer"))
     return PropertyValue(cell->isBuffer());
+  else if (stringEqual(property, "is_inverter"))
+    return PropertyValue(cell->isInverter());
   else if (stringEqual(property, "dont_use"))
     return PropertyValue(cell->dontUse());
   else