enable padding!=0 and fill height padding with 0

Author: tensor-tang

paddle/fluid/operators/math/im2col.cc

@@ -48,29 +48,63 @@ class Im2ColFunctor<paddle::operators::math::ColFormat::kCFO,
     const T* im_data = im.data<T>();
     T* col_data = col->data<T>();
     // TODO(TJ): change me to template
-    // further optimaze:
-    // 1. padding != 1
-    // 2. could also support stride_h != 1
+    // further optimize: padding == 1 need special
     if (stride[0] == 1 && stride[1] == 1 && dilation[0] == 1 &&
-        dilation[1] == 1 && padding[0] == 0 && padding[1] == 0) {
+        dilation[1] == 1) {
       int col_matrix_width = output_width * output_height;
       int im_size = im_height * im_width;
-      size_t copy_size = sizeof(T) * output_width;
-      for (int oh = 0; oh < output_height; ++oh) {
-        const T* im_data_start = im_data + oh * im_width;
-        T* dst_data = col_data + oh * output_width;
-        for (int ic = 0; ic < im_channels; ++ic) {
-          const T* src_data = im_data_start + ic * im_size;
-          for (int kh = 0; kh < filter_height; ++kh) {
+      if (padding[0] == 0 && padding[1] == 0) {
+        size_t copy_size = sizeof(T) * output_width;
+        for (int oh = 0; oh < output_height; ++oh) {
+          const T* im_data_start = im_data + oh * im_width;
+          T* dst_data = col_data + oh * output_width;
+          for (int ic = 0; ic < im_channels; ++ic) {
+            const T* src_data = im_data_start + ic * im_size;
+            for (int kh = 0; kh < filter_height; ++kh) {
+              for (int kw = 0; kw < filter_width; ++kw) {
+                std::memcpy(dst_data, src_data + kw, copy_size);
+                dst_data = dst_data + col_matrix_width;
+              }
+              src_data = src_data + im_width;
+            }
+          }
+        }
+        return;
+      } else {
+        int plh = padding[0];
+        // int plw = padding[1];
+        int prh =
+            (output_height - 1) * stride[0] + filter_height - im_height - plh;
+        // int prw =  (output_width - 1) * stride[1] + filter_width - im_width -
+        // plw;
+
+        // fill height padding : 0 ~ plh-1, (oh-prh) ~ (oh-1)
+        // TODO(TJ): reuse sizes
+        assert(plh == prh);  // because stride_h == 1
+        for (int ph = 0; ph < plh; ++ph) {
+          size_t sz = sizeof(T) * output_width * (plh - ph);
+          T* col_start_l = col_data + ph * filter_width * col_matrix_width;
+          T* col_start_r =
+              col_data +
+              (filter_width - ph - 1) * filter_width * col_matrix_width +
+              col_matrix_width - output_width * (plh - ph);
+          for (int ic = 0; ic < im_channels; ++ic) {
+            T* dst_data_l =
+                col_start_l +
+                ic * filter_width * filter_height * col_matrix_width;
+            T* dst_data_r =
+                col_start_r +
+                ic * filter_width * filter_height * col_matrix_width;
             for (int kw = 0; kw < filter_width; ++kw) {
-              std::memcpy(dst_data, src_data + kw, copy_size);
-              dst_data = dst_data + col_matrix_width;
+              std::memset(dst_data_l, 0, sz);
+              std::memset(dst_data_r, 0, sz);
+              dst_data_l = dst_data_l + col_matrix_width;
+              dst_data_r = dst_data_r + col_matrix_width;
             }
-            src_data = src_data + im_width;
           }
         }
+        return;
       }
-      return;
     }
 
     for (int c = 0; c < channels_col; ++c) {