Created by: Grant-Tao

这是链接：https://paddlepaddle.org.cn/documentation/docs/zh/advanced_guide/performance_improving/amp/amp.html 但运行出错，在API reference也找不到fluid.contrib.mixed_precision这个模块。错误如下：

  optimizer.minimize(loss)
  File "/opt/conda/envs/python35-paddle120-env/lib/python3.7/site-packages/paddle/fluid/contrib/mixed_precision/decorator.py", line 211, in minimize
    no_grad_set=no_grad_set)
  File "/opt/conda/envs/python35-paddle120-env/lib/python3.7/site-packages/paddle/fluid/contrib/mixed_precision/decorator.py", line 141, in backward
    update_role_var_grad(self._train_program, self._params_grads)
  File "/opt/conda/envs/python35-paddle120-env/lib/python3.7/site-packages/paddle/fluid/contrib/mixed_precision/fp16_utils.py", line 294, in update_role_var_grad
    op = g.op
AttributeError: 'paddle.fluid.core_avx.VarBase' object has no attribute 'op'

   1） PaddlePaddle版本：1.8    2）CPU， GPU， 系统环境：aistudio