From bc7610583bdc25ca7774e07c5426ee258628d792 Mon Sep 17 00:00:00 2001
From: Zhang Ting <709968123@qq.com>
Date: Mon, 6 Jul 2020 11:35:41 +0800
Subject: [PATCH] use eval() to improve CPU performance (#25243)

---
 paddle/fluid/operators/clip_by_norm_op.h | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/paddle/fluid/operators/clip_by_norm_op.h b/paddle/fluid/operators/clip_by_norm_op.h
index a2562c44d7..f6f9936963 100644
--- a/paddle/fluid/operators/clip_by_norm_op.h
+++ b/paddle/fluid/operators/clip_by_norm_op.h
@@ -82,7 +82,12 @@ class ClipByNormKernel : public framework::OpKernel<T> {
     auto scaling = temp + (static_cast<T>(1) - temp) * max_norm / x_norm;
     Eigen::array<int, 1> one_dim{{1}};
     Eigen::DSizes<int, 1> m_dsize(input->numel());
-    out.device(place) = x * scaling.reshape(one_dim).broadcast(m_dsize);
+    if (context.GetPlace() == platform::CPUPlace()) {
+      out.device(place) =
+          x * scaling.reshape(one_dim).eval().broadcast(m_dsize);
+    } else {
+      out.device(place) = x * scaling.reshape(one_dim).broadcast(m_dsize);
+    }
   }
 };