Xが4D、Yが3D、axisが0の場合に対応

python/test/function/test_broadcast_to.py

@@ -73,6 +73,10 @@ def ref_broadcast_to(x, y, axis):
             elif axis == 1:
                 t = y[np.newaxis, :, :, np.newaxis]
                 return np.broadcast_to(t, x.shape)
+        elif ys == 3:
+            if axis == 0:
+                t = y[:, :, :, np.newaxis]
+                return np.broadcast_to(t, x.shape)
 
 
 
@@ -91,7 +95,7 @@ def ref_broadcast_to(x, y, axis):
     ((2, 3, 4, 5), (2, 3), 0),
     ((2, 3, 4, 5), (3, 4), 1),
     ((2, 3, 4, 5), (4, 5), 2),
-    #((2, 3, 4, 5), (2, 3, 4), 0),
+    ((2, 3, 4, 5), (2, 3, 4), 0),
     ((2, 3, 4, 5), (3, 4, 5), 1),
     ((2, 3, 4, 5), (5), -1),
     ((2, 3, 4, 5), (4, 5), -1),

src/nbla/function/broadcast_to.cpp

@@ -282,7 +282,27 @@ void BroadcastTo<T>::forward_impl(const Variables &inputs, const Variables &outp
 				case 3:
 					switch(axis_) {
 						case 0:
-							// X: (2,3,4,5) Y: (2,3,4) axis=0
+							{
+								// X: (2,3,4,5) Y: (2,3,4) axis=0
+								Size_t y_buf_width = ys[2];
+								Size_t y_slice_size = ys[1]*y_buf_width;
+								Size_t z_row_width = xs[3];
+								Size_t z_slice_size = xs[2]*xs[3];
+								Size_t z_chan_size = xs[1]*z_slice_size;
+								for (Size_t n=0; n<xs[0]; n++) {
+									const T* ychan = &y[n*y_slice_size];
+									T* zslice = &z[n*z_chan_size];
+									for (Size_t c=0; c<xs[1]; c++) {
+										const T* yrow = &ychan[c*y_buf_width];
+										T* zblock = &zslice[c*z_slice_size];
+										for (Size_t h=0; h<xs[2]; h++) {
+											T val = yrow[h];
+											T* zrow = &zblock[h*z_row_width];
+											std::fill(zrow, zrow+z_row_width, val);
+										}
+									}
+								}
+							}
 							break;
 						case 1:
 							// X: (2,3,4,5) Y: (3,4,5) axis=1