Introduce internal_idx_t in ivf_pq::build()

cpp/include/raft/neighbors/detail/ivf_pq_build.cuh

@@ -61,6 +61,8 @@ namespace raft::neighbors::ivf_pq::detail {
 
 using namespace raft::spatial::knn::detail;  // NOLINT
 
+using internal_idx_t = int64_t;  // The default mdspan extent type used internally.
+
 template <uint32_t BlockDim, typename T, typename S>
 __launch_bounds__(BlockDim) RAFT_KERNEL copy_warped_kernel(
   T* out, uint32_t ld_out, const S* in, uint32_t ld_in, uint32_t n_cols, size_t n_rows)
@@ -442,15 +444,15 @@ void train_per_subset(raft::resources const& handle,
                  stream);
 
     // train PQ codebook for this subspace
-    auto sub_trainset_view = raft::make_device_matrix_view<const float, int64_t>(
+    auto sub_trainset_view = raft::make_device_matrix_view<const float, internal_idx_t>(
       sub_trainset.data(), n_rows, index.pq_len());
-    auto centers_tmp_view = raft::make_device_matrix_view<float, int64_t>(
+    auto centers_tmp_view = raft::make_device_matrix_view<float, internal_idx_t>(
       pq_centers_tmp.data() + index.pq_book_size() * index.pq_len() * j,
       index.pq_book_size(),
       index.pq_len());
     auto sub_labels_view =
-      raft::make_device_vector_view<uint32_t, int64_t>(sub_labels.data(), n_rows);
-    auto cluster_sizes_view = raft::make_device_vector_view<uint32_t, int64_t>(
+      raft::make_device_vector_view<uint32_t, internal_idx_t>(sub_labels.data(), n_rows);
+    auto cluster_sizes_view = raft::make_device_vector_view<uint32_t, internal_idx_t>(
       pq_cluster_sizes.data(), index.pq_book_size());
     raft::cluster::kmeans_balanced_params kmeans_params;
     kmeans_params.n_iters = kmeans_n_iters;
@@ -526,16 +528,16 @@ void train_per_cluster(raft::resources const& handle,
     size_t available_rows = size_t(cluster_size) * size_t(index.pq_dim());
     auto pq_n_rows        = uint32_t(std::min(big_enough, available_rows));
     // train PQ codebook for this cluster
-    auto rot_vectors_view = raft::make_device_matrix_view<const float, int64_t>(
+    auto rot_vectors_view = raft::make_device_matrix_view<const float, internal_idx_t>(
       rot_vectors.data(), pq_n_rows, index.pq_len());
-    auto centers_tmp_view = raft::make_device_matrix_view<float, int64_t>(
+    auto centers_tmp_view = raft::make_device_matrix_view<float, internal_idx_t>(
       pq_centers_tmp.data() + static_cast<size_t>(index.pq_book_size()) *
                                 static_cast<size_t>(index.pq_len()) * static_cast<size_t>(l),
       index.pq_book_size(),
       index.pq_len());
     auto pq_labels_view =
-      raft::make_device_vector_view<uint32_t, int64_t>(pq_labels.data(), pq_n_rows);
-    auto pq_cluster_sizes_view = raft::make_device_vector_view<uint32_t, int64_t>(
+      raft::make_device_vector_view<uint32_t, internal_idx_t>(pq_labels.data(), pq_n_rows);
+    auto pq_cluster_sizes_view = raft::make_device_vector_view<uint32_t, internal_idx_t>(
       pq_cluster_sizes.data(), index.pq_book_size());
     raft::cluster::kmeans_balanced_params kmeans_params;
     kmeans_params.n_iters = kmeans_n_iters;
@@ -1588,11 +1590,11 @@ void extend(raft::resources const& handle,
                                     cudaMemcpyDefault,
                                     stream));
     for (const auto& batch : vec_batches) {
-      auto batch_data_view =
-        raft::make_device_matrix_view<const T, int64_t>(batch.data(), batch.size(), index->dim());
-      auto batch_labels_view = raft::make_device_vector_view<uint32_t, int64_t>(
+      auto batch_data_view = raft::make_device_matrix_view<const T, internal_idx_t>(
+        batch.data(), batch.size(), index->dim());
+      auto batch_labels_view = raft::make_device_vector_view<uint32_t, internal_idx_t>(
         new_data_labels.data() + batch.offset(), batch.size());
-      auto centers_view = raft::make_device_matrix_view<const float, int64_t>(
+      auto centers_view = raft::make_device_matrix_view<const float, internal_idx_t>(
         cluster_centers.data(), n_clusters, index->dim());
       raft::cluster::kmeans_balanced_params kmeans_params;
       kmeans_params.metric = index->metric();
@@ -1768,10 +1770,10 @@ auto build(raft::resources const& handle,
     auto cluster_centers = cluster_centers_buf.data();
 
     // Train balanced hierarchical kmeans clustering
-    auto trainset_const_view = raft::make_device_matrix_view<const float, int64_t>(
+    auto trainset_const_view = raft::make_device_matrix_view<const float, internal_idx_t>(
       trainset.data(), n_rows_train, index.dim());
-    auto centers_view =
-      raft::make_device_matrix_view<float, int64_t>(cluster_centers, index.n_lists(), index.dim());
+    auto centers_view = raft::make_device_matrix_view<float, internal_idx_t>(
+      cluster_centers, index.n_lists(), index.dim());
     raft::cluster::kmeans_balanced_params kmeans_params;
     kmeans_params.n_iters = params.kmeans_n_iters;
     kmeans_params.metric  = index.metric();
@@ -1780,10 +1782,10 @@ auto build(raft::resources const& handle,
 
     // Trainset labels are needed for training PQ codebooks
     rmm::device_uvector<uint32_t> labels(n_rows_train, stream, device_memory);
-    auto centers_const_view = raft::make_device_matrix_view<const float, int64_t>(
+    auto centers_const_view = raft::make_device_matrix_view<const float, internal_idx_t>(
       cluster_centers, index.n_lists(), index.dim());
     auto labels_view =
-      raft::make_device_vector_view<uint32_t, int64_t>(labels.data(), n_rows_train);
+      raft::make_device_vector_view<uint32_t, internal_idx_t>(labels.data(), n_rows_train);
     raft::cluster::kmeans_balanced::predict(handle,
                                             kmeans_params,
                                             trainset_const_view,