Merge branch 'optimize_deconv_cpu' into 'master'

refactor deconv code

See merge request !819

mace/kernels/deconv_2d.h

@@ -191,20 +191,6 @@ struct Deconv2dFunctor<DeviceType::CPU, float>: Deconv2dFunctorBase {
                        const index_t *in_shape,
                        const index_t *out_shape,
                        float *output) {
-    const index_t kernel_size = kernel_h * kernel_w;
-    std::vector<int> out_map(kernel_size);
-    int p0 = 0;
-    int p1 = 0;
-    index_t gap = out_shape[3] - kernel_w;
-    for (int i = 0; i < kernel_h; ++i) {
-      for (int j = 0; j < kernel_w; ++j) {
-        out_map[p0] = p1;
-        p0++;
-        p1++;
-      }
-      p1 += gap;
-    }
-
     const index_t out_height = out_shape[2];
     const index_t out_width = out_shape[3];
     const index_t in_height = in_shape[2];
@@ -212,6 +198,14 @@ struct Deconv2dFunctor<DeviceType::CPU, float>: Deconv2dFunctorBase {
     const index_t out_img_size = out_height * out_width;
     const index_t in_img_size = in_height * in_width;
 
+    const int kernel_size = static_cast<int>(kernel_h * kernel_w);
+    std::vector<index_t> index_map(kernel_size, 0);
+    for (index_t i = 0; i < kernel_h; ++i) {
+      for (index_t j = 0; j < kernel_w; ++j) {
+        index_map[i * kernel_w + j] = i * out_width + j;
+      }
+    }
+
 #pragma omp parallel for
     for (int b = 0; b < in_shape[0]; ++b) {
       for (int oc = 0; oc < out_shape[1]; ++oc) {
@@ -230,7 +224,7 @@ struct Deconv2dFunctor<DeviceType::CPU, float>: Deconv2dFunctorBase {
               const index_t kernel_offset =
                   (oc * in_shape[1] + ic) * kernel_size;
               for (int k = 0; k < kernel_size; ++k) {
-                const index_t out_idx = out_offset + out_map[k];
+                const index_t out_idx = out_offset + index_map[k];
                 const index_t kernel_idx = kernel_offset + k;
                 out_base[out_idx] += val * filter[kernel_idx];
               }