Add conditional compile for gru opt#17368

Merged

zhaoyuchen2018 merged 6 commits intoPaddlePaddle:developfrom

zhaoyuchen2018:improveop

May 16, 2019

Commits on Apr 12, 2019

improve gru unit performance.
zhaoyuchen2018
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Commits on May 8, 2019

Merge commit 'refs/pull/16338/head' of https://github.com/PaddlePaddle/Paddle into improveop
zhaoyuchen2018
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Commits on May 9, 2019

Merge branch 'develop' of https://github.com/PaddlePaddle/Paddle into improveop
zhaoyuchen2018
committed

Commits on May 13, 2019

Commits on May 14, 2019

refine code.
zhaoyuchen2018
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