simplify the gpu gather implementation

src/targets/gpu/device/gather.cpp

@@ -23,28 +23,19 @@ argument gather(hipStream_t stream,
             const auto* indices_ptr = device_cast(indices.data());
             auto* out_ptr           = device_cast(output.data());
             const auto* in_ptr      = device_cast(input.data());
-            if(output_shape.scalar())
-            {
-                gs_launch(stream, 1)(
-                    [=](auto i) { out_ptr[i] = in_ptr[static_cast<int>(indices_ptr[0])]; });
-            }
-            else
-            {
-                // if indices are a scalar, output has one dim smaller than input
-                auto& input_shape = args[0].get_shape();
-                auto lens         = input_shape.lens();
-                lens[axis_index]  = args[1].get_shape().elements();
-                migraphx::shape out_comp_shape{output_shape.type(), lens};
-                visit_tensor_size(out_comp_shape.lens().size(), [&](auto n_out_dim) {
-                    hip_tensor_descriptor<n_out_dim> desc_input(input_shape);
-                    hip_tensor_descriptor<n_out_dim> desc_output(out_comp_shape);
-                    gs_launch(stream, nelements)([=](auto ii) {
-                        auto in_idx        = desc_output.multi(ii);
-                        in_idx[axis_index] = indices_ptr[in_idx[axis_index]];
-                        out_ptr[ii]        = in_ptr[desc_input.linear(in_idx)];
-                    });
+            auto& input_shape = args[0].get_shape();
+            auto lens         = input_shape.lens();
+            lens[axis_index]  = args[1].get_shape().elements();
+            migraphx::shape out_comp_shape{output_shape.type(), lens};
+            visit_tensor_size(out_comp_shape.lens().size(), [&](auto n_out_dim) {
+                hip_tensor_descriptor<n_out_dim> desc_input(input_shape);
+                hip_tensor_descriptor<n_out_dim> desc_output(out_comp_shape);
+                gs_launch(stream, nelements)([=](auto ii) {
+                    auto in_idx        = desc_output.multi(ii);
+                    in_idx[axis_index] = indices_ptr[in_idx[axis_index]];
+                    out_ptr[ii]        = in_ptr[desc_input.linear(in_idx)];
                 });
-            }
+            });
         });
     });