Add grad_name Property for Class Variable (#20991)

python/paddle/fluid/framework.py

@@ -1131,6 +1131,26 @@ class Variable(object):
         else:
             return cpt.to_text(self.desc.name())
 
+    @property
+    def grad_name(self):
+        """
+        Indicating name of the gradient Variable of current Variable.
+
+        **Notes: This is a read-only property. It simply returns name of
+          gradient Variable from a naming convention but doesn't guarantee
+          the gradient exists.**
+       
+        Examples:
+          .. code-block:: python
+
+          import paddle.fluid as fluid
+
+          x = fluid.data(name="x", shape=[-1, 23, 48], dtype='float32')
+          print(x.grad_name) # output is "x@GRAD"
+
+        """
+        return self.name + "@GRAD"
+
     @name.setter
     def name(self, new_name):
         if in_dygraph_mode():

python/paddle/fluid/tests/unittests/test_variable.py

@@ -44,12 +44,14 @@ class TestVariable(unittest.TestCase):
         self.assertEqual(core.VarDesc.VarType.FP64, w.dtype)
         self.assertEqual((784, 100), w.shape)
         self.assertEqual("fc.w", w.name)
+        self.assertEqual("fc.w@GRAD", w.grad_name)
         self.assertEqual(0, w.lod_level)
 
         w = b.create_var(name='fc.w')
         self.assertEqual(core.VarDesc.VarType.FP64, w.dtype)
         self.assertEqual((784, 100), w.shape)
         self.assertEqual("fc.w", w.name)
+        self.assertEqual("fc.w@GRAD", w.grad_name)
         self.assertEqual(0, w.lod_level)
 
         self.assertRaises(ValueError,