support tf rint op

Signed-off-by: hwangdeyu <dejack953@outlook.com>
Co-authored-by: fatcat-z <jiz@microsoft.com>

tests/test_backend.py

@@ -4609,6 +4609,14 @@ def func(x):
             return tf.identity(x_, name=_TFOUTPUT)
         self._run_test_case(func, [_OUTPUT], {_INPUT: x_val})
 
+    @check_opset_min_version(11, "Round")
+    def test_rint(self):
+        x_val = np.array([-2.7, -1.5, -0.0, +0.0, 0.3, 0.5, 1.5, 2.5, 3.4, 3.5, float('nan')], dtype=np.float32)
+        def func(x):
+            x_ = tf.math.rint(x)
+            return tf.identity(x_, name=_TFOUTPUT)
+        self._run_test_case(func, [_OUTPUT], {_INPUT: x_val})
+
     @check_opset_min_version(11, "Det")
     @unittest.skip("unclear how this is called in tf-2, fix later")
     def test_determinant(self):

tf2onnx/onnx_opset/math.py

@@ -559,6 +559,15 @@ def version_11(cls, ctx, node, **kwargs):
         pass
 
 
+@tf_op("Rint", onnx_op="Round")
+class Rint:
+    @classmethod
+    def version_11(cls, ctx, node, **kwargs):
+        # Same with tf round, two different people just happened to write the function.
+        # https://github.com/tensorflow/tensorflow/issues/709
+        pass
+
+
 @tf_op("MatrixDeterminant", onnx_op="Det")
 class Det:
     @classmethod