fix framework warning (#2059)

ppdet/modeling/backbones/fpn.py

@@ -18,7 +18,6 @@ from __future__ import print_function
 
 from collections import OrderedDict
 import copy
-import paddle
 from paddle import fluid
 from paddle.fluid.param_attr import ParamAttr
 from paddle.fluid.initializer import Xavier
@@ -106,7 +105,7 @@ class FPN(object):
                 out_shape=[body_input.shape[2], body_input.shape[3]],
                 name=topdown_name)
 
-        return paddle.add(lateral, topdown)
+        return fluid.layers.elementwise_add(lateral, topdown)
 
     def get_output(self, body_dict):
         """

ppdet/modeling/backbones/mobilenet_v3.py

@@ -225,7 +225,7 @@ class MobileNetV3(object):
         return out
 
     def _hard_swish(self, x):
-        return x * fluid.layers.relu6(x + 3) / 6.
+        return fluid.layers.elementwise_mul(x, fluid.layers.relu6(x + 3) / 6.)
 
     def _se_block(self, input, num_out_filter, ratio=4, name=None):
         lr_idx = self.curr_stage // 3

ppdet/modeling/ops.py

@@ -325,7 +325,8 @@ def DropBlock(input, block_size, keep_prob, is_test):
     elem_sum_m = fluid.layers.cast(elem_sum, dtype="float32")
     elem_sum_m.stop_gradient = True
 
-    output = input * mask * elem_numel_m / elem_sum_m
+    output = fluid.layers.elementwise_mul(input,
+                                          mask) * elem_numel_m / elem_sum_m
     return output