From a6ef875885486eea5573e4da52ec2c1c02f1d1e7 Mon Sep 17 00:00:00 2001
From: chengduoZH <zhaochengduo@163.com>
Date: Mon, 11 Dec 2017 14:05:15 +0800
Subject: [PATCH] refine conv

---
 paddle/operators/conv_op.h           | 7 +++++--
 paddle/operators/conv_transpose_op.h | 2 +-
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/paddle/operators/conv_op.h b/paddle/operators/conv_op.h
index 09bff0a68db..66728d75a66 100644
--- a/paddle/operators/conv_op.h
+++ b/paddle/operators/conv_op.h
@@ -260,8 +260,11 @@ class GemmConvGradKernel : public framework::OpKernel<T> {
 
     if (input_grad) {
       input_grad->mutable_data<T>(context.GetPlace());
-      set_zero(context.device_context(), input_grad, static_cast<T>(0));
-
+      // if is_expand is false, the operation of set_zero is unnecessary,
+      // because math::matmul will reset input_grad.
+      if (is_expand) {
+        set_zero(context.device_context(), input_grad, static_cast<T>(0));
+      }
       math::Col2VolFunctor<Place, T> col2vol;
       math::Col2ImFunctor<math::ColFormat::kCFO, Place, T> col2im;
 
diff --git a/paddle/operators/conv_transpose_op.h b/paddle/operators/conv_transpose_op.h
index 1cacb770e6a..a43dd5b8c0d 100644
--- a/paddle/operators/conv_transpose_op.h
+++ b/paddle/operators/conv_transpose_op.h
@@ -225,7 +225,7 @@ class GemmConvTransposeGradKernel : public framework::OpKernel<T> {
 
       if (input_grad) {
         input_grad->mutable_data<T>(context.GetPlace());
-        set_zero(context.device_context(), input_grad, static_cast<T>(0));
+        // set_zero is unnecessary, math::matmul will reset input_grad.
       }
       if (filter_grad) {  // filter size (m, c, k_h, k_w)
         filter_grad->mutable_data<T>(context.GetPlace());
-- 
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