Add support for overloading comparison operations in relay (#2910)

This commit adds support for overloaded comparison operators
in the python binding for relay.

Add a testcase for this

Author: Ramana Radhakrishnan

python/tvm/relay/expr.py

@@ -70,6 +70,38 @@ def astype(self, dtype):
     def __neg__(self):
         return _op_make.negative(self)
 
+    def __lt__(self, other):
+        if isinstance(other, Expr):
+            return _op_make.less(self, other)
+        elif isinstance(other, _Number):
+            raise TypeError('convert "%s" with `const` first' % str(other))
+        else:
+            raise TypeError("type %s not supported" % str(type(other)))
+
+    def __gt__(self, other):
+        if isinstance(other, Expr):
+            return _op_make.greater(self, other)
+        elif isinstance(other, _Number):
+            raise TypeError('convert "%s" with `const` first' % str(other))
+        else:
+            raise TypeError("type %s not supported" % str(type(other)))
+
+    def __ge__(self, other):
+        if isinstance(other, Expr):
+            return _op_make.greater_equal(self, other)
+        elif isinstance(other, _Number):
+            raise TypeError('convert "%s" with `const` first' % str(other))
+        else:
+            raise TypeError("type %s not supported" % str(type(other)))
+
+    def __le__(self, other):
+        if isinstance(other, Expr):
+            return _op_make.less_equal(self, other)
+        elif isinstance(other, _Number):
+            raise TypeError('convert "%s" with `const` first' % str(other))
+        else:
+            raise TypeError("type %s not supported" % str(type(other)))
+
     def __add__(self, other):
         if isinstance(other, Expr):
             return _op_make.add(self, other)

tests/python/relay/test_cmp_op.py

@@ -0,0 +1,36 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+from tvm import relay
+a = relay.Var("a")
+b = relay.expr.const (1.0, dtype='float32')
+
+c = a < b
+d = relay.less (a, b)
+assert (c.astext() == d.astext())
+
+c = a > b
+d = relay.greater (a, b)
+assert (c.astext() == d.astext())
+
+c = (a >= b)
+d = relay.greater_equal(a, b)
+assert (c.astext() == d.astext())
+
+c = (a <= b)
+d = relay.less_equal(a, b)
+assert (c.astext() == d.astext())