!1926 Skip operations which are not supported by the backend in PyNative Mode

Merge pull request !1926 from BowenK/op_elim

mindspore/ops/operations/array_ops.py

@@ -185,6 +185,13 @@ class Cast(PrimitiveWithInfer):
         """init Cast"""
         self.init_prim_io_names(inputs=['x', 'dst_type'], outputs=['output'])
 
+    def check_elim(self, x, dtype):
+        if isinstance(x, Tensor):
+            if x.dtype() == dtype:
+                return (True, x)
+            return (False, None)
+        raise ValueError("Expecting (Tensor, dtype), got : {}".format(inputs))
+
     def __infer__(self, x, t):
         src_type = x['dtype']
         dst_type = t['value']
@@ -1345,6 +1352,15 @@ class Tile(PrimitiveWithInfer):
         """init Tile"""
         self.init_prim_io_names(inputs=['x', 'multiples'], outputs=['output'])
 
+    def check_elim(self, base_tensor, multiplier):
+        if (not isinstance(base_tensor, Tensor)) or (not isinstance(multiplier, tuple)):
+            raise ValueError("Expecting (Tensor, tuple), got: ({}, {})".format(base_tensor, multiplier))
+        def is_all_zeros(v_tuple):
+            return all(v == 1 for v in v_tuple)
+        if is_all_zeros(multiplier):
+            return (True, base_tensor)
+        return (False, None)
+
     def __infer__(self, x, multiples):
         multiples_v = multiples['value']
         x_shp = x['shape']

mindspore/ops/operations/math_ops.py

@@ -715,6 +715,13 @@ class AddN(PrimitiveWithInfer):
     def __init__(self):
         self.init_prim_io_names(inputs=["inputs"], outputs=["sum"])
 
+    def check_elim(self, inputs):
+        if len(inputs) != 1:
+            return (False, None)
+        if isinstance(inputs[0], Tensor):
+            return (True, inputs[0])
+        raise TypeError("Expecting Tensor, got : {}".format(type(inputs[0])))
+
     def infer_shape(self, inputs):
         cls_name = self.name
         validator.check_integer("inputs", len(inputs), 1, Rel.GE, cls_name)

mindspore/ops/primitive.py

@@ -140,9 +140,24 @@ class Primitive(Primitive_):
             return self.attrs[item]
         raise AttributeError(item)
 
+    def check_elim(self, *args):
+        """
+        Check whether or not certain inputs should go into backend. Subclass in need should override this method.
+
+        Args:
+            Same as arguments of current Primitive
+
+        Returns:
+            A tuple of two elements, first element indicates whether or not we should filter out current arguments;
+            seconde element is the output in case where we should filter out the arguments.
+        """
+        return (False, None)
+
     def __call__(self, *args):
-        output = _run_op(self, self.name, args)
-        return output
+        should_elim, output = self.check_elim(*args)
+        if should_elim:
+            return output
+        return _run_op(self, self.name, args)
 
     def __getstate__(self):
         return self.__dict__