remove redundant operations in Crop layer (#5138)

2 files changed, 27 insertions, 35 deletions

diff --git a/src/caffe/layers/crop_layer.cpp b/src/caffe/layers/crop_layer.cpp
index d36b61ca..ef8c177c 100644
--- a/src/caffe/layers/crop_layer.cpp
+++ b/src/caffe/layers/crop_layer.cpp
@@ -86,27 +86,25 @@ void CropLayer<Dtype>::crop_copy(const vector<Blob<Dtype>*>& bottom,
     }
   } else {
     // We are at the last dimensions, which is stored continuously in memory
-    for (int i = 0; i < top[0]->shape(cur_dim); ++i) {
-      // prepare index vector reduced(red) and with offsets(off)
-      std::vector<int> ind_red(cur_dim, 0);
-      std::vector<int> ind_off(cur_dim+1, 0);
-      for (int j = 0; j < cur_dim; ++j) {
-          ind_red[j] = indices[j];
-          ind_off[j] = indices[j] + offsets[j];
-      }
-      ind_off[cur_dim] = offsets[cur_dim];
-      // do the copy
-      if (is_forward) {
-        caffe_copy(top[0]->shape(cur_dim),
-            src_data + bottom[0]->offset(ind_off),
-            dest_data + top[0]->offset(ind_red));
-      } else {
-        // in the backwards pass the src_data is top_diff
-        // and the dest_data is bottom_diff
-        caffe_copy(top[0]->shape(cur_dim),
-            src_data + top[0]->offset(ind_red),
-            dest_data + bottom[0]->offset(ind_off));
-      }
+    // prepare index vector reduced(red) and with offsets(off)
+    std::vector<int> ind_red(cur_dim, 0);
+    std::vector<int> ind_off(cur_dim+1, 0);
+    for (int j = 0; j < cur_dim; ++j) {
+      ind_red[j] = indices[j];
+      ind_off[j] = indices[j] + offsets[j];
+    }
+    ind_off[cur_dim] = offsets[cur_dim];
+    // do the copy
+    if (is_forward) {
+      caffe_copy(top[0]->shape(cur_dim),
+          src_data + bottom[0]->offset(ind_off),
+          dest_data + top[0]->offset(ind_red));
+    } else {
+      // in the backwards pass the src_data is top_diff
+      // and the dest_data is bottom_diff
+      caffe_copy(top[0]->shape(cur_dim),
+          src_data + top[0]->offset(ind_red),
+          dest_data + bottom[0]->offset(ind_off));
     }
   }
 }
diff --git a/src/caffe/layers/crop_layer.cu b/src/caffe/layers/crop_layer.cu
index 1ea13253..677077cd 100644
--- a/src/caffe/layers/crop_layer.cu
+++ b/src/caffe/layers/crop_layer.cu
@@ -8,14 +8,12 @@ namespace caffe {
 // strides in the last two dimensions.
 template <typename Dtype>
 __global__ void copy_kernel(const int n, const int height, const int width,
-    const int src_outer_stride, const int src_inner_stride,
-    const int dest_outer_stride, const int dest_inner_stride,
+    const int src_inner_stride,
+    const int dest_inner_stride,
     const Dtype* src, Dtype* dest) {
   CUDA_KERNEL_LOOP(index, n) {
-    int src_start = index / height * src_outer_stride
-                  + index % height * src_inner_stride;
-    int dest_start = index / height * dest_outer_stride
-                   + index % height * dest_inner_stride;
+    int src_start = index * src_inner_stride;
+    int dest_start = index * dest_inner_stride;
     for (int i = 0; i < width; ++i) {
       dest[dest_start + i] = src[src_start + i];
     }
@@ -53,11 +51,7 @@ void CropLayer<Dtype>::crop_copy_gpu(const vector<Blob<Dtype>*>& bottom,
     ind_off[cur_dim] = offsets[cur_dim];
     ind_off[cur_dim+1] = offsets[cur_dim+1];
     // Compute copy strides
-    const int src_outer_stride =
-        bottom[0]->shape(cur_dim)*bottom[0]->shape(cur_dim+1);
     const int src_inner_stride = bottom[0]->shape(cur_dim+1);
-    const int dest_outer_stride =
-        top[0]->shape(cur_dim)*top[0]->shape(cur_dim+1);
     const int dest_inner_stride = top[0]->shape(cur_dim+1);
 
     if (is_forward) {
@@ -68,8 +62,8 @@ void CropLayer<Dtype>::crop_copy_gpu(const vector<Blob<Dtype>*>& bottom,
       // NOLINT_NEXT_LINE(whitespace/operators)
       copy_kernel<<<CAFFE_GET_BLOCKS(lines), CAFFE_CUDA_NUM_THREADS>>>(
           lines, height, width,
-          src_outer_stride, src_inner_stride,
-          dest_outer_stride, dest_inner_stride,
+          src_inner_stride,
+          dest_inner_stride,
           bottom_data, top_data);
 
     } else {
@@ -80,8 +74,8 @@ void CropLayer<Dtype>::crop_copy_gpu(const vector<Blob<Dtype>*>& bottom,
       // NOLINT_NEXT_LINE(whitespace/operators)
       copy_kernel<<<CAFFE_GET_BLOCKS(lines), CAFFE_CUDA_NUM_THREADS>>>(
           lines, height, width,
-          dest_outer_stride, dest_inner_stride,
-          src_outer_stride, src_inner_stride,
+          dest_inner_stride,
+          src_inner_stride,
           top_diff, bottom_diff);
     }
   }