Created by: qingqing01

Fix https://github.com/PaddlePaddle/Paddle/issues/7001

• Test Env:

  • model config: https://github.com/dzhwinter/benchmark/blob/master/fluid/understand_sentiment_dynamic_lstm.py
  • CPU, 2 epoc

• Total Time:

  • 109.56469s -> 51.86136s