Add explicit read into registers

Author: oleksandr-pavlyk

dpctl/tensor/libtensor/include/kernels/sorting/topk.hpp

@@ -149,8 +149,9 @@ topk_full_merge_sort_impl(sycl::queue &exec_q,
             std::size_t src_idx = iter_gid * axis_nelems + axis_gid;
             std::size_t dst_idx = iter_gid * k + axis_gid;
 
-            auto res_ind = index_data[src_idx];
-            vals_tp[dst_idx] = arg_tp[res_ind];
+            const IndexTy res_ind = index_data[src_idx];
+            const argTy v = arg_tp[res_ind];
+            vals_tp[dst_idx] = v;
             inds_tp[dst_idx] = res_ind % axis_nelems;
         });
     });
@@ -425,8 +426,9 @@ sycl::event topk_merge_impl(
                 const std::size_t src_idx = iter_gid * alloc_len + axis_gid;
                 const std::size_t dst_idx = gid;
 
-                const auto res_ind = index_data[src_idx];
-                vals_tp[dst_idx] = arg_tp[res_ind];
+                const IndexTy res_ind = index_data[src_idx];
+                const argTy v = arg_tp[res_ind];
+                vals_tp[dst_idx] = v;
                 inds_tp[dst_idx] = (res_ind % axis_nelems);
             });
         });
@@ -538,11 +540,14 @@ sycl::event topk_radix_impl(sycl::queue &exec_q,
             const std::size_t dst_idx = gid;
 
             const IndexTy res_ind = tmp_tp[src_idx];
-            vals_tp[dst_idx] = arg_tp[res_ind];
+            const v = arg_tp[res_ind];
+            vals_tp[dst_idx] = v;
             inds_tp[dst_idx] = (res_ind % axis_nelems);
         });
     });
 
+    write_topk_ev.wait();
+
     sycl::event cleanup_ev = exec_q.submit([&](sycl::handler &cgh) {
         cgh.depends_on(write_topk_ev);