add namespace aliases to reduce code

src/data/data.cu

@@ -17,6 +17,9 @@
 
 #if defined(XGBOOST_USE_HIP)
 namespace cub = hipcub;
+namespace thrust {
+    namespace cuda = thrust::hip;
+}
 #endif
 
 namespace xgboost {
@@ -122,13 +125,8 @@ void CopyQidImpl(ArrayInterface<1> array_interface, std::vector<bst_group_t>* p_
   group_ptr_.resize(h_num_runs_out + 1, 0);
   dh::XGBCachingDeviceAllocator<char> alloc;
 
-#if defined(XGBOOST_USE_CUDA)
   thrust::inclusive_scan(thrust::cuda::par(alloc), cnt.begin(),
                          cnt.begin() + h_num_runs_out, cnt.begin());
-#elif defined(XGBOOST_USE_HIP)
-  thrust::inclusive_scan(thrust::hip::par(alloc), cnt.begin(),
-                         cnt.begin() + h_num_runs_out, cnt.begin());
-#endif
 
   thrust::copy(cnt.begin(), cnt.begin() + h_num_runs_out,
                group_ptr_.begin() + 1);

src/data/device_adapter.cuh

@@ -17,6 +17,12 @@
 #include "adapter.h"
 #include "array_interface.h"
 
+#if defined(XGBOOST_USE_HIP)
+namespace thrust {
+    namespace cuda = thrust::hip;
+}
+#endif
+
 namespace xgboost {
 namespace data {
 
@@ -246,17 +252,10 @@ std::size_t GetRowCounts(const AdapterBatchT batch, common::Span<bst_row_t> offs
   });
 
   dh::XGBCachingDeviceAllocator<char> alloc;
-#if defined(XGBOOST_USE_CUDA)
   bst_row_t row_stride =
       dh::Reduce(thrust::cuda::par(alloc), thrust::device_pointer_cast(offset.data()),
                  thrust::device_pointer_cast(offset.data()) + offset.size(),
                  static_cast<bst_row_t>(0), thrust::maximum<bst_row_t>());
-#elif defined(XGBOOST_USE_HIP)
-  bst_row_t row_stride =
-      dh::Reduce(thrust::hip::par(alloc), thrust::device_pointer_cast(offset.data()),
-                 thrust::device_pointer_cast(offset.data()) + offset.size(),
-                 static_cast<bst_row_t>(0), thrust::maximum<bst_row_t>());
-#endif
   return row_stride;
 }
 
@@ -280,13 +279,8 @@ bool NoInfInData(AdapterBatchT const& batch, IsValidFunctor is_valid) {
   // intervals to early stop. But we expect all data to be valid here, using small
   // intervals only decreases performance due to excessive kernel launch and stream
   // synchronization.
-#if defined(XGBOOST_USE_CUDA)
   auto valid = dh::Reduce(thrust::cuda::par(alloc), value_iter, value_iter + batch.Size(), true,
                           thrust::logical_and<>{});
-#elif defined(XGBOOST_USE_HIP)
-  auto valid = dh::Reduce(thrust::hip::par(alloc), value_iter, value_iter + batch.Size(), true,
-                          thrust::logical_and<>{});
-#endif
   return valid;
 }
 };  // namespace data

src/data/iterative_dmatrix.cu

@@ -16,6 +16,12 @@
 #include "simple_batch_iterator.h"
 #include "sparse_page_source.h"
 
+#if defined(XGBOOST_USE_HIP)
+namespace thrust {
+    namespace cuda = thrust::hip;
+}
+#endif
+
 namespace xgboost::data {
 void IterativeDMatrix::InitFromCUDA(Context const* ctx, BatchParam const& p,
                                     DataIterHandle iter_handle, float missing,
@@ -86,11 +92,7 @@ void IterativeDMatrix::InitFromCUDA(Context const* ctx, BatchParam const& p,
                             return GetRowCounts(value, row_counts_span, get_device(), missing);
                           }));
 
-#if defined(XGBOOST_USE_CUDA)
     nnz += thrust::reduce(thrust::cuda::par(alloc), row_counts.begin(), row_counts.end());
-#elif defined(XGBOOST_USE_HIP)
-    nnz += thrust::reduce(thrust::hip::par(alloc), row_counts.begin(), row_counts.end());
-#endif
 
     batches++;
   } while (iter.Next());

src/data/simple_dmatrix.cuh

@@ -13,6 +13,12 @@
 #include "../common/error_msg.h"  // for InfInData
 #include "device_adapter.cuh"     // for HasInfInData
 
+#if defined(XGBOOST_USE_HIP)
+namespace thrust {
+    namespace cuda = thrust::hip;
+}
+#endif
+
 namespace xgboost::data {
 
 #if defined(XGBOOST_USE_CUDA)
@@ -69,15 +75,9 @@ void CountRowOffsets(const AdapterBatchT& batch, common::Span<bst_row_t> offset,
   });
 
   dh::XGBCachingDeviceAllocator<char> alloc;
-#if defined(XGBOOST_USE_CUDA)
   thrust::exclusive_scan(thrust::cuda::par(alloc), thrust::device_pointer_cast(offset.data()),
                          thrust::device_pointer_cast(offset.data() + offset.size()),
                          thrust::device_pointer_cast(offset.data()));
-#elif defined(XGBOOST_USE_HIP)
-  thrust::exclusive_scan(thrust::hip::par(alloc), thrust::device_pointer_cast(offset.data()),
-                         thrust::device_pointer_cast(offset.data() + offset.size()),
-                         thrust::device_pointer_cast(offset.data()));
-#endif
 }
 
 template <typename AdapterBatchT>