refine width padding and enable core copy

Author: tensor-tang

paddle/fluid/operators/math/im2col.cc

@@ -126,11 +126,9 @@ class Im2ColFunctor<paddle::operators::math::ColFormat::kCFO,
           // padding_size > 1
           for (int ic = 0; ic < im_channels; ++ic) {
             // TODO(TJ): use add and resue stride
-            T* dst_data_ic =
-                col_data + ic * filter_width * filter_height * col_matrix_width;
+            T* dst_data_ic = col_data + ic * col_block_ic;
             for (int kh = 0; kh < filter_height; ++kh) {
-              T* dst_data_kh =
-                  dst_data_ic + kh * filter_width * col_matrix_width;
+              T* dst_data_kh = dst_data_ic + kh * col_block_fh;
               for (int kw = 0; kw < plw; ++kw) {
                 // TODO(TJ): reuse array outside this for
                 size_t sz = sizeof(T) * (plw - kw);
@@ -158,6 +156,67 @@ class Im2ColFunctor<paddle::operators::math::ColFormat::kCFO,
             }
           }
         }
+
+        // fill im_data
+        // padding cover two cases:
+        // 1. kw > 2*pw: kw = 3, pw = 1
+        // 0 x x x x ... x x x x 0
+        // 1 1 1             1 1 1
+        // ==>
+        // 0 x ... x x
+        // x x ... x x
+        // x x ... x 0
+        // 2. kw < 2*pw: kw = 3, pw = 2
+        // 0 0 x x x ... x x x 0 0
+        // 1 1 1             1 1 1
+        // ==>
+        // 0 0 x ... x x x
+        // 0 x x ... x x 0
+        // x x x ... x 0 0
+
+        // TODO(TJ): use array like: size_t copy_size[kw]={sizeof(T) *
+        // (output_width-1)}
+        // length of copy_size is equal kw.
+        if (plw + prw < filter_width) {
+          for (int oh = 0; oh < output_height; ++oh) {
+            const T* im_data_start =
+                im_data + (oh - plh > 0 ? oh - plh : 0) * 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 ((oh < plh && kh < plh) ||
+                    (oh > (output_height - prh - 1) &&
+                     kh > (filter_height - prh - 1))) {
+                  dst_data = dst_data + filter_width * col_matrix_width;
+                  continue;
+                }
+                // TODO(TJ): reuse plw-kw outside this for
+                // try to unify
+                for (int kw = 0; kw < plw; ++kw) {
+                  std::memcpy(dst_data + (plw - kw), src_data,
+                              sizeof(T) * (output_width - (plw - kw)));
+                  dst_data = dst_data + col_matrix_width;
+                }
+                for (int kw = plw; kw < filter_width - prw; ++kw) {
+                  std::memcpy(dst_data, src_data + (kw - plw),
+                              sizeof(T) * output_width);
+                  dst_data = dst_data + col_matrix_width;
+                }
+                int i = 1;
+                for (int kw = filter_width - prw; kw < filter_width;
+                     ++kw, ++i) {
+                  std::memcpy(dst_data, src_data + (kw - plw),
+                              sizeof(T) * (output_width - i));
+                  dst_data = dst_data + col_matrix_width;
+                }
+                src_data = src_data + im_width;
+              }
+            }
+          }
+        } else {
+          LOG(FATAL) << "Not implement yet";
+        }
         return;
       }
     }