!3655 gpu support BroadcastTo kernel

Merge pull request !3655 from chenweifeng/broadcast_to

mindspore/ccsrc/backend/kernel_compiler/gpu/arrays/broadcast_to_gpu_kernel.h

@@ -51,11 +51,12 @@ class BroadcastToGpuKernel : public GpuKernel {
       MS_LOG(EXCEPTION) << "BroadcastTo operation not support dim greater than 4";
     }
 
-    for (int i = input_shapes.size() - 1; i >= 0; i--) {
-      input_shape_[i] = input_shapes[i];
+    size_t offset = output_shapes.size() - input_shapes.size();
+    for (size_t i = 0; i < input_shapes.size(); i++) {
+      input_shape_[i + offset] = input_shapes[i];
     }
 
-    for (int j = output_shapes.size() - 1; j >= 0; j--) {
+    for (size_t j = 0; j < output_shapes.size(); j++) {
       output_shape_[j] = output_shapes[j];
     }
 

tests/st/ops/gpu/test_broadcast_to_ops.py

@@ -38,3 +38,9 @@ def test_broadcast():
     output = P.BroadcastTo(shape)(Tensor(x1_np))
     expect = np.broadcast_to(x1_np, shape)
     assert np.allclose(output.asnumpy(), expect)
+
+    x1_np = np.random.rand(4, 5).astype(np.float32)
+    shape = (2, 3, 4, 5)
+    output = P.BroadcastTo(shape)(Tensor(x1_np))
+    expect = np.broadcast_to(x1_np, shape)
+    assert np.allclose(output.asnumpy(), expect)