Unify test helpers for creating ctx. (#9274)

tests/cpp/common/test_algorithm.cu

@@ -11,7 +11,7 @@
 
 #include "../../../src/common/algorithm.cuh"
 #include "../../../src/common/device_helpers.cuh"
-#include "../helpers.h"  // CreateEmptyGenericParam
+#include "../helpers.h"  // MakeCUDACtx
 
 namespace xgboost {
 namespace common {
@@ -83,7 +83,7 @@ TEST(Algorithm, GpuArgSort) {
 TEST(Algorithm, SegmentedSequence) {
   dh::device_vector<std::size_t> idx(16);
   dh::device_vector<std::size_t> ptr(3);
-  Context ctx = CreateEmptyGenericParam(0);
+  Context ctx = MakeCUDACtx(0);
   ptr[0] = 0;
   ptr[1] = 4;
   ptr[2] = idx.size();

tests/cpp/common/test_column_matrix.cc

@@ -14,7 +14,7 @@ TEST(DenseColumn, Test) {
   int32_t max_num_bins[] = {static_cast<int32_t>(std::numeric_limits<uint8_t>::max()) + 1,
                             static_cast<int32_t>(std::numeric_limits<uint16_t>::max()) + 1,
                             static_cast<int32_t>(std::numeric_limits<uint16_t>::max()) + 2};
-  auto ctx = CreateEmptyGenericParam(Context::kCpuId);
+  Context ctx;
   BinTypeSize last{kUint8BinsTypeSize};
   for (int32_t max_num_bin : max_num_bins) {
     auto dmat = RandomDataGenerator(100, 10, 0.0).GenerateDMatrix();
@@ -63,7 +63,7 @@ TEST(SparseColumn, Test) {
   int32_t max_num_bins[] = {static_cast<int32_t>(std::numeric_limits<uint8_t>::max()) + 1,
                             static_cast<int32_t>(std::numeric_limits<uint16_t>::max()) + 1,
                             static_cast<int32_t>(std::numeric_limits<uint16_t>::max()) + 2};
-  auto ctx = CreateEmptyGenericParam(Context::kCpuId);
+  Context ctx;
   for (int32_t max_num_bin : max_num_bins) {
     auto dmat = RandomDataGenerator(100, 1, 0.85).GenerateDMatrix();
     GHistIndexMatrix gmat{&ctx, dmat.get(), max_num_bin, 0.5f, false};
@@ -92,7 +92,7 @@ TEST(DenseColumnWithMissing, Test) {
   int32_t max_num_bins[] = {static_cast<int32_t>(std::numeric_limits<uint8_t>::max()) + 1,
                             static_cast<int32_t>(std::numeric_limits<uint16_t>::max()) + 1,
                             static_cast<int32_t>(std::numeric_limits<uint16_t>::max()) + 2};
-  auto ctx = CreateEmptyGenericParam(Context::kCpuId);
+  Context ctx;
   for (int32_t max_num_bin : max_num_bins) {
     auto dmat = RandomDataGenerator(100, 1, 0.5).GenerateDMatrix();
     GHistIndexMatrix gmat(&ctx, dmat.get(), max_num_bin, 0.2, false);

tests/cpp/common/test_hist_util.cc

@@ -156,28 +156,28 @@ TEST(CutsBuilder, SearchGroupInd) {
 }
 
 TEST(HistUtil, DenseCutsCategorical) {
-  auto ctx = CreateEmptyGenericParam(Context::kCpuId);
+  Context ctx;
-   int categorical_sizes[] = {2, 6, 8, 12};
+  int categorical_sizes[] = {2, 6, 8, 12};
-   int num_bins = 256;
+  int num_bins = 256;
-   int sizes[] = {25, 100, 1000};
+  int sizes[] = {25, 100, 1000};
-   for (auto n : sizes) {
+  for (auto n : sizes) {
-     for (auto num_categories : categorical_sizes) {
+    for (auto num_categories : categorical_sizes) {
-       auto x = GenerateRandomCategoricalSingleColumn(n, num_categories);
+      auto x = GenerateRandomCategoricalSingleColumn(n, num_categories);
-       std::vector<float> x_sorted(x);
+      std::vector<float> x_sorted(x);
-       std::sort(x_sorted.begin(), x_sorted.end());
+      std::sort(x_sorted.begin(), x_sorted.end());
-       auto dmat = GetDMatrixFromData(x, n, 1);
+      auto dmat = GetDMatrixFromData(x, n, 1);
-       HistogramCuts cuts = SketchOnDMatrix(&ctx, dmat.get(), num_bins);
+      HistogramCuts cuts = SketchOnDMatrix(&ctx, dmat.get(), num_bins);
-       auto cuts_from_sketch = cuts.Values();
+      auto cuts_from_sketch = cuts.Values();
-       EXPECT_LT(cuts.MinValues()[0], x_sorted.front());
+      EXPECT_LT(cuts.MinValues()[0], x_sorted.front());
-       EXPECT_GT(cuts_from_sketch.front(), x_sorted.front());
+      EXPECT_GT(cuts_from_sketch.front(), x_sorted.front());
-       EXPECT_GE(cuts_from_sketch.back(), x_sorted.back());
+      EXPECT_GE(cuts_from_sketch.back(), x_sorted.back());
-       EXPECT_EQ(cuts_from_sketch.size(), static_cast<size_t>(num_categories));
+      EXPECT_EQ(cuts_from_sketch.size(), static_cast<size_t>(num_categories));
-     }
+    }
-   }
+  }
 }
 
 TEST(HistUtil, DenseCutsAccuracyTest) {
-  auto ctx = CreateEmptyGenericParam(Context::kCpuId);
+  Context ctx;
   int bin_sizes[] = {2, 16, 256, 512};
   int sizes[] = {100};
   int num_columns = 5;
@@ -195,7 +195,7 @@ TEST(HistUtil, DenseCutsAccuracyTestWeights) {
   int bin_sizes[] = {2, 16, 256, 512};
   int sizes[] = {100, 1000, 1500};
   int num_columns = 5;
-  auto ctx = CreateEmptyGenericParam(Context::kCpuId);
+  Context ctx;
   for (auto num_rows : sizes) {
     auto x = GenerateRandom(num_rows, num_columns);
     auto dmat = GetDMatrixFromData(x, num_rows, num_columns);
@@ -218,7 +218,7 @@ void TestQuantileWithHessian(bool use_sorted) {
   int bin_sizes[] = {2, 16, 256, 512};
   int sizes[] = {1000, 1500};
   int num_columns = 5;
-  auto ctx = CreateEmptyGenericParam(Context::kCpuId);
+  Context ctx;
   for (auto num_rows : sizes) {
     auto x = GenerateRandom(num_rows, num_columns);
     auto dmat = GetDMatrixFromData(x, num_rows, num_columns);
@@ -257,7 +257,7 @@ TEST(HistUtil, DenseCutsExternalMemory) {
   int bin_sizes[] = {2, 16, 256, 512};
   int sizes[] = {100, 1000, 1500};
   int num_columns = 5;
-  auto ctx = CreateEmptyGenericParam(Context::kCpuId);
+  Context ctx;
   for (auto num_rows : sizes) {
     auto x = GenerateRandom(num_rows, num_columns);
     dmlc::TemporaryDirectory tmpdir;
@@ -278,7 +278,7 @@ TEST(HistUtil, IndexBinBound) {
                                            kUint32BinsTypeSize};
   size_t constexpr kRows = 100;
   size_t constexpr kCols = 10;
-  auto ctx = CreateEmptyGenericParam(Context::kCpuId);
+  Context ctx;
   size_t bin_id = 0;
   for (auto max_bin : bin_sizes) {
     auto p_fmat = RandomDataGenerator(kRows, kCols, 0).GenerateDMatrix();
@@ -303,7 +303,7 @@ TEST(HistUtil, IndexBinData) {
                                      static_cast<uint64_t>(std::numeric_limits<uint16_t>::max()) + 2 };
   size_t constexpr kRows = 100;
   size_t constexpr kCols = 10;
-  auto ctx = CreateEmptyGenericParam(Context::kCpuId);
+  Context ctx;
 
   for (auto max_bin : kBinSizes) {
     auto p_fmat = RandomDataGenerator(kRows, kCols, 0).GenerateDMatrix();
@@ -331,7 +331,7 @@ void TestSketchFromWeights(bool with_group) {
   size_t constexpr kRows = 300, kCols = 20, kBins = 256;
   size_t constexpr kGroups = 10;
   auto m = RandomDataGenerator{kRows, kCols, 0}.Device(0).GenerateDMatrix();
-  auto ctx = CreateEmptyGenericParam(Context::kCpuId);
+  Context ctx;
   common::HistogramCuts cuts = SketchOnDMatrix(&ctx, m.get(), kBins);
 
   MetaInfo info;
@@ -397,7 +397,7 @@ TEST(HistUtil, SketchFromWeights) {
 }
 
 TEST(HistUtil, SketchCategoricalFeatures) {
-  auto ctx = CreateEmptyGenericParam(Context::kCpuId);
+  Context ctx;
   TestCategoricalSketch(1000, 256, 32, false, [&ctx](DMatrix* p_fmat, int32_t num_bins) {
     return SketchOnDMatrix(&ctx, p_fmat, num_bins);
   });

tests/cpp/common/test_hist_util.cu

@@ -310,7 +310,7 @@ TEST(HistUtil, AdapterDeviceSketch) {
   data::CupyAdapter adapter(str);
 
   auto device_cuts = MakeUnweightedCutsForTest(adapter, num_bins, missing);
-  auto ctx = CreateEmptyGenericParam(Context::kCpuId);
+  Context ctx;
   auto host_cuts = GetHostCuts(&ctx, &adapter, num_bins, missing);
 
   EXPECT_EQ(device_cuts.Values(), host_cuts.Values());

tests/cpp/common/test_quantile.cc

@@ -302,7 +302,7 @@ namespace {
 void TestSameOnAllWorkers() {
   auto const world = collective::GetWorldSize();
   constexpr size_t kRows = 1000, kCols = 100;
-  auto ctx = CreateEmptyGenericParam(Context::kCpuId);
+  Context ctx;
 
   RunWithSeedsAndBins(
       kRows, [=, &ctx](int32_t seed, size_t n_bins, MetaInfo const&) {

tests/cpp/data/test_gradient_index.cc

@@ -21,7 +21,7 @@
 #include "../../../src/data/adapter.h"          // for SparsePageAdapterBatch
 #include "../../../src/data/gradient_index.h"   // for GHistIndexMatrix
 #include "../../../src/tree/param.h"            // for TrainParam
-#include "../helpers.h"                         // for CreateEmptyGenericParam, GenerateRandomCa...
+#include "../helpers.h"                         // for GenerateRandomCategoricalSingleColumn...
 #include "xgboost/base.h"                       // for bst_bin_t
 #include "xgboost/context.h"                    // for Context
 #include "xgboost/host_device_vector.h"         // for HostDeviceVector
@@ -29,7 +29,7 @@
 namespace xgboost {
 namespace data {
 TEST(GradientIndex, ExternalMemory) {
-  auto ctx = CreateEmptyGenericParam(Context::kCpuId);
+  Context ctx;
   std::unique_ptr<DMatrix> dmat = CreateSparsePageDMatrix(10000);
   std::vector<size_t> base_rowids;
   std::vector<float> hessian(dmat->Info().num_row_, 1);
@@ -58,7 +58,7 @@ TEST(GradientIndex, FromCategoricalBasic) {
   size_t max_bins = 8;
   auto x = GenerateRandomCategoricalSingleColumn(kRows, kCats);
   auto m = GetDMatrixFromData(x, kRows, 1);
-  auto ctx = CreateEmptyGenericParam(Context::kCpuId);
+  Context ctx;
 
   auto &h_ft = m->Info().feature_types.HostVector();
   h_ft.resize(kCols, FeatureType::kCategorical);

tests/cpp/data/test_sparse_page_dmatrix.cc

@@ -67,7 +67,7 @@ void TestSparseDMatrixLoadFile(Context const* ctx) {
 }
 
 TEST(SparsePageDMatrix, LoadFile) {
-  auto ctx = CreateEmptyGenericParam(Context::kCpuId);
+  Context ctx;
   TestSparseDMatrixLoadFile<SparsePage>(&ctx);
   TestSparseDMatrixLoadFile<CSCPage>(&ctx);
   TestSparseDMatrixLoadFile<SortedCSCPage>(&ctx);
@@ -77,7 +77,7 @@ TEST(SparsePageDMatrix, LoadFile) {
 template <typename Page>
 void TestRetainPage() {
   auto m = CreateSparsePageDMatrix(10000);
-  auto ctx = CreateEmptyGenericParam(Context::kCpuId);
+  Context ctx;
   auto batches = m->GetBatches<Page>(&ctx);
   auto begin = batches.begin();
   auto end = batches.end();
@@ -145,7 +145,7 @@ TEST(SparsePageDMatrix, ColAccess) {
   const std::string tmp_file = tempdir.path + "/simple.libsvm";
   CreateSimpleTestData(tmp_file);
   xgboost::DMatrix *dmat = xgboost::DMatrix::Load(UriSVM(tmp_file, tmp_file));
-  auto ctx = CreateEmptyGenericParam(Context::kCpuId);
+  Context ctx;
 
   // Loop over the batches and assert the data is as expected
   size_t iter = 0;
@@ -224,7 +224,7 @@ TEST(SparsePageDMatrix, ColAccessBatches) {
   // Create multiple sparse pages
   std::unique_ptr<xgboost::DMatrix> dmat{xgboost::CreateSparsePageDMatrix(kEntries)};
   ASSERT_EQ(dmat->Ctx()->Threads(), AllThreadsForTest());
-  auto ctx = CreateEmptyGenericParam(Context::kCpuId);
+  Context ctx;
   for (auto const &page : dmat->GetBatches<xgboost::CSCPage>(&ctx)) {
     ASSERT_EQ(dmat->Info().num_col_, page.Size());
   }

tests/cpp/data/test_sparse_page_dmatrix.cu

@@ -108,7 +108,7 @@ TEST(SparsePageDMatrix, RetainEllpackPage) {
 }
 
 TEST(SparsePageDMatrix, EllpackPageContent) {
-  auto ctx = CreateEmptyGenericParam(0);
+  auto ctx = MakeCUDACtx(0);
   constexpr size_t kRows = 6;
   constexpr size_t kCols = 2;
   constexpr size_t kPageSize = 1;

tests/cpp/helpers.h

@@ -382,13 +382,6 @@ std::unique_ptr<GradientBooster> CreateTrainedGBM(std::string name, Args kwargs,
                                                   LearnerModelParam const* learner_model_param,
                                                   Context const* generic_param);
 
-inline Context CreateEmptyGenericParam(int gpu_id) {
-  xgboost::Context tparam;
-  std::vector<std::pair<std::string, std::string>> args{{"gpu_id", std::to_string(gpu_id)}};
-  tparam.Init(args);
-  return tparam;
-}
-
 inline std::unique_ptr<HostDeviceVector<GradientPair>> GenerateGradients(
     std::size_t rows, bst_target_t n_targets = 1) {
   auto p_gradients = std::make_unique<HostDeviceVector<GradientPair>>(rows * n_targets);
@@ -407,9 +400,14 @@ inline std::unique_ptr<HostDeviceVector<GradientPair>> GenerateGradients(
 }
 
 /**
- * \brief Make a context that uses CUDA.
+ * \brief Make a context that uses CUDA if device >= 0.
  */
-inline Context MakeCUDACtx(std::int32_t device) { return Context{}.MakeCUDA(device); }
+inline Context MakeCUDACtx(std::int32_t device) {
+  if (device == Context::kCpuId) {
+    return Context{};
+  }
+  return Context{}.MakeCUDA(device);
+}
 
 inline HostDeviceVector<GradientPair> GenerateRandomGradients(const size_t n_rows,
                                                               float lower= 0.0f, float upper = 1.0f) {

tests/cpp/linear/test_json_io.h

@@ -12,19 +12,19 @@
 
 namespace xgboost {
 inline void TestUpdaterJsonIO(std::string updater_str) {
-  auto runtime = xgboost::CreateEmptyGenericParam(GPUIDX);
+  Context ctx{MakeCUDACtx(GPUIDX)};
   Json config_0 {Object() };
 
   {
-    auto updater = std::unique_ptr<xgboost::LinearUpdater>(
+    auto updater =
-        xgboost::LinearUpdater::Create(updater_str, &runtime));
+        std::unique_ptr<xgboost::LinearUpdater>(xgboost::LinearUpdater::Create(updater_str, &ctx));
     updater->Configure({{"eta", std::to_string(3.14)}});
     updater->SaveConfig(&config_0);
   }
 
   {
-    auto updater = std::unique_ptr<xgboost::LinearUpdater>(
+    auto updater =
-        xgboost::LinearUpdater::Create(updater_str, &runtime));
+        std::unique_ptr<xgboost::LinearUpdater>(xgboost::LinearUpdater::Create(updater_str, &ctx));
     updater->LoadConfig(config_0);
     Json config_1 { Object() };
     updater->SaveConfig(&config_1);

tests/cpp/linear/test_linear.cc

@@ -17,7 +17,7 @@ TEST(Linear, Shotgun) {
 
   auto p_fmat = xgboost::RandomDataGenerator(kRows, kCols, 0).GenerateDMatrix();
 
-  auto ctx = xgboost::CreateEmptyGenericParam(GPUIDX);
+  auto ctx = MakeCUDACtx(GPUIDX);
   LearnerModelParam mparam{MakeMP(kCols, .5, 1)};
 
   {
@@ -49,7 +49,7 @@ TEST(Linear, coordinate) {
 
   auto p_fmat = xgboost::RandomDataGenerator(kRows, kCols, 0).GenerateDMatrix();
 
-  auto ctx = xgboost::CreateEmptyGenericParam(GPUIDX);
+  auto ctx = MakeCUDACtx(GPUIDX);
   LearnerModelParam mparam{MakeMP(kCols, .5, 1)};
 
   auto updater = std::unique_ptr<xgboost::LinearUpdater>(

tests/cpp/linear/test_linear.cu

@@ -13,7 +13,7 @@ TEST(Linear, GPUCoordinate) {
   size_t constexpr kCols = 10;
 
   auto mat = xgboost::RandomDataGenerator(kRows, kCols, 0).GenerateDMatrix();
-  auto ctx = CreateEmptyGenericParam(GPUIDX);
+  auto ctx = MakeCUDACtx(0);
 
   LearnerModelParam mparam{MakeMP(kCols, .5, 1)};
   auto updater = std::unique_ptr<xgboost::LinearUpdater>(

tests/cpp/metric/test_auc.h

@@ -11,7 +11,7 @@ namespace xgboost {
 namespace metric {
 
 inline void VerifyBinaryAUC(DataSplitMode data_split_mode = DataSplitMode::kRow) {
-  auto ctx = xgboost::CreateEmptyGenericParam(GPUIDX);
+  auto ctx = MakeCUDACtx(GPUIDX);
   std::unique_ptr<Metric> uni_ptr{Metric::Create("auc", &ctx)};
   Metric* metric = uni_ptr.get();
   ASSERT_STREQ(metric->Name(), "auc");
@@ -54,7 +54,7 @@ inline void VerifyBinaryAUC(DataSplitMode data_split_mode = DataSplitMode::kRow)
 }
 
 inline void VerifyMultiClassAUC(DataSplitMode data_split_mode = DataSplitMode::kRow) {
-  auto ctx = CreateEmptyGenericParam(GPUIDX);
+  auto ctx = MakeCUDACtx(GPUIDX);
   std::unique_ptr<Metric> uni_ptr{Metric::Create("auc", &ctx)};
   auto metric = uni_ptr.get();
 
@@ -115,7 +115,7 @@ inline void VerifyMultiClassAUC(DataSplitMode data_split_mode = DataSplitMode::k
 }
 
 inline void VerifyRankingAUC(DataSplitMode data_split_mode = DataSplitMode::kRow) {
-  auto ctx = CreateEmptyGenericParam(GPUIDX);
+  auto ctx = MakeCUDACtx(GPUIDX);
   std::unique_ptr<Metric> metric{Metric::Create("auc", &ctx)};
 
   // single group
@@ -149,7 +149,7 @@ inline void VerifyRankingAUC(DataSplitMode data_split_mode = DataSplitMode::kRow
 }
 
 inline void VerifyPRAUC(DataSplitMode data_split_mode = DataSplitMode::kRow) {
-  auto ctx = xgboost::CreateEmptyGenericParam(GPUIDX);
+  auto ctx = MakeCUDACtx(GPUIDX);
 
   xgboost::Metric* metric = xgboost::Metric::Create("aucpr", &ctx);
   ASSERT_STREQ(metric->Name(), "aucpr");
@@ -186,7 +186,7 @@ inline void VerifyPRAUC(DataSplitMode data_split_mode = DataSplitMode::kRow) {
 }
 
 inline void VerifyMultiClassPRAUC(DataSplitMode data_split_mode = DataSplitMode::kRow) {
-  auto ctx = xgboost::CreateEmptyGenericParam(GPUIDX);
+  auto ctx = MakeCUDACtx(GPUIDX);
 
   std::unique_ptr<Metric> metric{Metric::Create("aucpr", &ctx)};
 
@@ -210,7 +210,7 @@ inline void VerifyMultiClassPRAUC(DataSplitMode data_split_mode = DataSplitMode:
 }
 
 inline void VerifyRankingPRAUC(DataSplitMode data_split_mode = DataSplitMode::kRow) {
-  auto ctx = xgboost::CreateEmptyGenericParam(GPUIDX);
+  auto ctx = MakeCUDACtx(GPUIDX);
 
   std::unique_ptr<Metric> metric{Metric::Create("aucpr", &ctx)};
 

tests/cpp/metric/test_elementwise_metric.h

@@ -15,7 +15,7 @@ namespace xgboost {
 namespace metric {
 
 inline void CheckDeterministicMetricElementWise(StringView name, int32_t device) {
-  auto ctx = CreateEmptyGenericParam(device);
+  auto ctx = MakeCUDACtx(device);
   std::unique_ptr<Metric> metric{Metric::Create(name.c_str(), &ctx)};
 
   HostDeviceVector<float> predts;
@@ -46,7 +46,7 @@ inline void CheckDeterministicMetricElementWise(StringView name, int32_t device)
 }
 
 inline void VerifyRMSE(DataSplitMode data_split_mode = DataSplitMode::kRow) {
-  auto ctx = xgboost::CreateEmptyGenericParam(GPUIDX);
+  auto ctx = MakeCUDACtx(GPUIDX);
   xgboost::Metric * metric = xgboost::Metric::Create("rmse", &ctx);
   metric->Configure({});
   ASSERT_STREQ(metric->Name(), "rmse");
@@ -75,7 +75,7 @@ inline void VerifyRMSE(DataSplitMode data_split_mode = DataSplitMode::kRow) {
 }
 
 inline void VerifyRMSLE(DataSplitMode data_split_mode = DataSplitMode::kRow) {
-  auto ctx = xgboost::CreateEmptyGenericParam(GPUIDX);
+  auto ctx = MakeCUDACtx(GPUIDX);
   xgboost::Metric * metric = xgboost::Metric::Create("rmsle", &ctx);
   metric->Configure({});
   ASSERT_STREQ(metric->Name(), "rmsle");
@@ -104,7 +104,7 @@ inline void VerifyRMSLE(DataSplitMode data_split_mode = DataSplitMode::kRow) {
 }
 
 inline void VerifyMAE(DataSplitMode data_split_mode = DataSplitMode::kRow) {
-  auto ctx = xgboost::CreateEmptyGenericParam(GPUIDX);
+  auto ctx = MakeCUDACtx(GPUIDX);
   xgboost::Metric * metric = xgboost::Metric::Create("mae", &ctx);
   metric->Configure({});
   ASSERT_STREQ(metric->Name(), "mae");
@@ -133,7 +133,7 @@ inline void VerifyMAE(DataSplitMode data_split_mode = DataSplitMode::kRow) {
 }
 
 inline void VerifyMAPE(DataSplitMode data_split_mode = DataSplitMode::kRow) {
-  auto ctx = xgboost::CreateEmptyGenericParam(GPUIDX);
+  auto ctx = MakeCUDACtx(GPUIDX);
   xgboost::Metric * metric = xgboost::Metric::Create("mape", &ctx);
   metric->Configure({});
   ASSERT_STREQ(metric->Name(), "mape");
@@ -162,7 +162,7 @@ inline void VerifyMAPE(DataSplitMode data_split_mode = DataSplitMode::kRow) {
 }
 
 inline void VerifyMPHE(DataSplitMode data_split_mode = DataSplitMode::kRow) {
-  auto ctx = xgboost::CreateEmptyGenericParam(GPUIDX);
+  auto ctx = MakeCUDACtx(GPUIDX);
   std::unique_ptr<xgboost::Metric> metric{xgboost::Metric::Create("mphe", &ctx)};
   metric->Configure({});
   ASSERT_STREQ(metric->Name(), "mphe");
@@ -197,7 +197,7 @@ inline void VerifyMPHE(DataSplitMode data_split_mode = DataSplitMode::kRow) {
 }
 
 inline void VerifyLogLoss(DataSplitMode data_split_mode = DataSplitMode::kRow) {
-  auto ctx = xgboost::CreateEmptyGenericParam(GPUIDX);
+  auto ctx = MakeCUDACtx(GPUIDX);
   xgboost::Metric * metric = xgboost::Metric::Create("logloss", &ctx);
   metric->Configure({});
   ASSERT_STREQ(metric->Name(), "logloss");
@@ -230,7 +230,7 @@ inline void VerifyLogLoss(DataSplitMode data_split_mode = DataSplitMode::kRow) {
 }
 
 inline void VerifyError(DataSplitMode data_split_mode = DataSplitMode::kRow) {
-  auto ctx = xgboost::CreateEmptyGenericParam(GPUIDX);
+  auto ctx = MakeCUDACtx(GPUIDX);
   xgboost::Metric * metric = xgboost::Metric::Create("error", &ctx);
   metric->Configure({});
   ASSERT_STREQ(metric->Name(), "error");
@@ -292,7 +292,7 @@ inline void VerifyError(DataSplitMode data_split_mode = DataSplitMode::kRow) {
 }
 
 inline void VerifyPoissonNegLogLik(DataSplitMode data_split_mode = DataSplitMode::kRow) {
-  auto ctx = xgboost::CreateEmptyGenericParam(GPUIDX);
+  auto ctx = MakeCUDACtx(GPUIDX);
   xgboost::Metric * metric = xgboost::Metric::Create("poisson-nloglik", &ctx);
   metric->Configure({});
   ASSERT_STREQ(metric->Name(), "poisson-nloglik");
@@ -332,7 +332,7 @@ inline void VerifyMultiRMSE(DataSplitMode data_split_mode = DataSplitMode::kRow)
 
   HostDeviceVector<float> predt(n_samples * n_targets, 0);
 
-  auto ctx = xgboost::CreateEmptyGenericParam(GPUIDX);
+  auto ctx = MakeCUDACtx(GPUIDX);
   std::unique_ptr<Metric> metric{Metric::Create("rmse", &ctx)};
   metric->Configure({});
 
@@ -347,7 +347,7 @@ inline void VerifyMultiRMSE(DataSplitMode data_split_mode = DataSplitMode::kRow)
 }
 
 inline void VerifyQuantile(DataSplitMode data_split_mode = DataSplitMode::kRow) {
-  auto ctx = xgboost::CreateEmptyGenericParam(GPUIDX);
+  auto ctx = MakeCUDACtx(GPUIDX);
   std::unique_ptr<Metric> metric{Metric::Create("quantile", &ctx)};
 
   HostDeviceVector<float> predts{0.1f, 0.9f, 0.1f, 0.9f};

tests/cpp/metric/test_metric.cc

@@ -2,10 +2,10 @@
 #include <xgboost/metric.h>
 
 #include "../helpers.h"
-
+namespace xgboost {
 TEST(Metric, UnknownMetric) {
-  auto ctx = xgboost::CreateEmptyGenericParam(GPUIDX);
+  auto ctx = MakeCUDACtx(GPUIDX);
-  xgboost::Metric * metric = nullptr;
+  xgboost::Metric* metric = nullptr;
   EXPECT_ANY_THROW(metric = xgboost::Metric::Create("unknown_name", &ctx));
   EXPECT_NO_THROW(metric = xgboost::Metric::Create("rmse", &ctx));
   if (metric) {
@@ -18,3 +18,4 @@ TEST(Metric, UnknownMetric) {
     delete metric;
   }
 }
+}  // namespace xgboost

tests/cpp/metric/test_multiclass_metric.h

@@ -8,7 +8,7 @@ namespace xgboost {
 namespace metric {
 
 inline void CheckDeterministicMetricMultiClass(StringView name, int32_t device) {
-  auto ctx = CreateEmptyGenericParam(device);
+  auto ctx = MakeCUDACtx(device);
   std::unique_ptr<Metric> metric{Metric::Create(name.c_str(), &ctx)};
 
   HostDeviceVector<float> predts;
@@ -45,7 +45,7 @@ inline void CheckDeterministicMetricMultiClass(StringView name, int32_t device)
 }
 
 inline void TestMultiClassError(int device, DataSplitMode data_split_mode) {
-  auto ctx = xgboost::CreateEmptyGenericParam(device);
+  auto ctx = MakeCUDACtx(device);
   ctx.gpu_id = device;
   xgboost::Metric * metric = xgboost::Metric::Create("merror", &ctx);
   metric->Configure({});
@@ -66,7 +66,7 @@ inline void VerifyMultiClassError(DataSplitMode data_split_mode = DataSplitMode:
 }
 
 inline void TestMultiClassLogLoss(int device, DataSplitMode data_split_mode) {
-  auto ctx = xgboost::CreateEmptyGenericParam(device);
+  auto ctx = MakeCUDACtx(device);
   ctx.gpu_id = device;
   xgboost::Metric * metric = xgboost::Metric::Create("mlogloss", &ctx);
   metric->Configure({});

tests/cpp/metric/test_rank_metric.cc

@@ -22,7 +22,7 @@ namespace metric {
 
 #if !defined(__CUDACC__)
 TEST(Metric, AMS) {
-  auto ctx = CreateEmptyGenericParam(GPUIDX);
+  auto ctx = MakeCUDACtx(GPUIDX);
   EXPECT_ANY_THROW(Metric::Create("ams", &ctx));
   Metric* metric = Metric::Create("ams@0.5f", &ctx);
   ASSERT_STREQ(metric->Name(), "ams@0.5");

tests/cpp/metric/test_rank_metric.h

@@ -20,7 +20,7 @@
 namespace xgboost::metric {
 
 inline void VerifyPrecision(DataSplitMode data_split_mode = DataSplitMode::kRow) {
-  auto ctx = xgboost::CreateEmptyGenericParam(GPUIDX);
+  auto ctx = MakeCUDACtx(GPUIDX);
   std::unique_ptr<xgboost::Metric> metric{Metric::Create("pre", &ctx)};
   ASSERT_STREQ(metric->Name(), "pre");
   EXPECT_NEAR(GetMetricEval(metric.get(), {0, 1}, {0, 1}, {}, {}, data_split_mode), 0.5, 1e-7);
@@ -44,7 +44,7 @@ inline void VerifyPrecision(DataSplitMode data_split_mode = DataSplitMode::kRow)
 }
 
 inline void VerifyNDCG(DataSplitMode data_split_mode = DataSplitMode::kRow) {
-  auto ctx = CreateEmptyGenericParam(GPUIDX);
+  auto ctx = MakeCUDACtx(GPUIDX);
   Metric * metric = xgboost::Metric::Create("ndcg", &ctx);
   ASSERT_STREQ(metric->Name(), "ndcg");
   EXPECT_ANY_THROW(GetMetricEval(metric, {0, 1}, {}, {}, {}, data_split_mode));
@@ -102,7 +102,7 @@ inline void VerifyNDCG(DataSplitMode data_split_mode = DataSplitMode::kRow) {
 }
 
 inline void VerifyMAP(DataSplitMode data_split_mode = DataSplitMode::kRow) {
-  auto ctx = xgboost::CreateEmptyGenericParam(GPUIDX);
+  auto ctx = MakeCUDACtx(GPUIDX);
   Metric * metric = xgboost::Metric::Create("map", &ctx);
   ASSERT_STREQ(metric->Name(), "map");
   EXPECT_NEAR(GetMetricEval(metric, {0, 1}, {0, 1}, {}, {}, data_split_mode), 1, kRtEps);
@@ -150,7 +150,7 @@ inline void VerifyMAP(DataSplitMode data_split_mode = DataSplitMode::kRow) {
 }
 
 inline void VerifyNDCGExpGain(DataSplitMode data_split_mode = DataSplitMode::kRow) {
-  Context ctx = xgboost::CreateEmptyGenericParam(GPUIDX);
+  Context ctx = MakeCUDACtx(GPUIDX);
 
   auto p_fmat = xgboost::RandomDataGenerator{0, 0, 0}.GenerateDMatrix();
   MetaInfo& info = p_fmat->Info();

tests/cpp/metric/test_survival_metric.cu

@@ -31,7 +31,7 @@ TEST_F(DeclareUnifiedDistributedTest(MetricTest), IntervalRegressionAccuracyColu
 
 // Test configuration of AFT metric
 TEST(AFTNegLogLikMetric, DeclareUnifiedTest(Configuration)) {
-  auto ctx = xgboost::CreateEmptyGenericParam(GPUIDX);
+  auto ctx = MakeCUDACtx(GPUIDX);
   std::unique_ptr<Metric> metric(Metric::Create("aft-nloglik", &ctx));
   metric->Configure({{"aft_loss_distribution", "normal"}, {"aft_loss_distribution_scale", "10"}});
 

tests/cpp/metric/test_survival_metric.h

@@ -13,7 +13,7 @@
 namespace xgboost {
 namespace common {
 inline void CheckDeterministicMetricElementWise(StringView name, int32_t device) {
-  auto ctx = CreateEmptyGenericParam(device);
+  auto ctx = MakeCUDACtx(device);
   std::unique_ptr<Metric> metric{Metric::Create(name.c_str(), &ctx)};
   metric->Configure(Args{});
 
@@ -48,7 +48,7 @@ inline void CheckDeterministicMetricElementWise(StringView name, int32_t device)
 }
 
 inline void VerifyAFTNegLogLik(DataSplitMode data_split_mode = DataSplitMode::kRow) {
-  auto ctx = xgboost::CreateEmptyGenericParam(GPUIDX);
+  auto ctx = MakeCUDACtx(GPUIDX);
 
   /**
    * Test aggregate output from the AFT metric over a small test data set.
@@ -79,7 +79,7 @@ inline void VerifyAFTNegLogLik(DataSplitMode data_split_mode = DataSplitMode::kR
 }
 
 inline void VerifyIntervalRegressionAccuracy(DataSplitMode data_split_mode = DataSplitMode::kRow) {
-  auto ctx = xgboost::CreateEmptyGenericParam(GPUIDX);
+  auto ctx = MakeCUDACtx(GPUIDX);
 
   auto p_fmat = EmptyDMatrix();
   MetaInfo& info = p_fmat->Info();

tests/cpp/objective/test_aft_obj.cc

@@ -16,7 +16,7 @@ namespace xgboost {
 namespace common {
 
 TEST(Objective, DeclareUnifiedTest(AFTObjConfiguration)) {
-  auto ctx = CreateEmptyGenericParam(GPUIDX);
+  auto ctx = MakeCUDACtx(GPUIDX);
   std::unique_ptr<ObjFunction> objective(ObjFunction::Create("survival:aft", &ctx));
   objective->Configure({ {"aft_loss_distribution", "logistic"},
                           {"aft_loss_distribution_scale", "5"} });
@@ -77,7 +77,7 @@ static inline void CheckGPairOverGridPoints(
 }
 
 TEST(Objective, DeclareUnifiedTest(AFTObjGPairUncensoredLabels)) {
-  auto ctx = CreateEmptyGenericParam(GPUIDX);
+  auto ctx = MakeCUDACtx(GPUIDX);
   std::unique_ptr<ObjFunction> obj(ObjFunction::Create("survival:aft", &ctx));
 
   CheckGPairOverGridPoints(obj.get(), 100.0f, 100.0f, "normal",
@@ -101,7 +101,7 @@ TEST(Objective, DeclareUnifiedTest(AFTObjGPairUncensoredLabels)) {
 }
 
 TEST(Objective, DeclareUnifiedTest(AFTObjGPairLeftCensoredLabels)) {
-  auto ctx = CreateEmptyGenericParam(GPUIDX);
+  auto ctx = MakeCUDACtx(GPUIDX);
   std::unique_ptr<ObjFunction> obj(ObjFunction::Create("survival:aft", &ctx));
 
   CheckGPairOverGridPoints(obj.get(), 0.0f, 20.0f, "normal",
@@ -122,7 +122,7 @@ TEST(Objective, DeclareUnifiedTest(AFTObjGPairLeftCensoredLabels)) {
 }
 
 TEST(Objective, DeclareUnifiedTest(AFTObjGPairRightCensoredLabels)) {
-  auto ctx = CreateEmptyGenericParam(GPUIDX);
+  auto ctx = MakeCUDACtx(GPUIDX);
   std::unique_ptr<ObjFunction> obj(ObjFunction::Create("survival:aft", &ctx));
 
   CheckGPairOverGridPoints(obj.get(), 60.0f, std::numeric_limits<float>::infinity(), "normal",
@@ -146,7 +146,7 @@ TEST(Objective, DeclareUnifiedTest(AFTObjGPairRightCensoredLabels)) {
 }
 
 TEST(Objective, DeclareUnifiedTest(AFTObjGPairIntervalCensoredLabels)) {
-  auto ctx = CreateEmptyGenericParam(GPUIDX);
+  auto ctx = MakeCUDACtx(GPUIDX);
   std::unique_ptr<ObjFunction> obj(ObjFunction::Create("survival:aft", &ctx));
 
   CheckGPairOverGridPoints(obj.get(), 16.0f, 200.0f, "normal",

tests/cpp/objective/test_hinge.cc

@@ -4,14 +4,12 @@
 #include <limits>
 
 #include "../helpers.h"
-
+namespace xgboost {
 TEST(Objective, DeclareUnifiedTest(HingeObj)) {
-  xgboost::Context ctx = xgboost::CreateEmptyGenericParam(GPUIDX);
+  Context ctx = MakeCUDACtx(GPUIDX);
-  std::unique_ptr<xgboost::ObjFunction> obj {
+  std::unique_ptr<ObjFunction> obj{ObjFunction::Create("binary:hinge", &ctx)};
-    xgboost::ObjFunction::Create("binary:hinge", &ctx)
-  };
 
-  xgboost::bst_float eps = std::numeric_limits<xgboost::bst_float>::min();
+  float eps = std::numeric_limits<xgboost::bst_float>::min();
   CheckObjFunction(obj,
                    {-1.0f, -0.5f, 0.5f, 1.0f, -1.0f, -0.5f,  0.5f, 1.0f},
                    { 0.0f,  0.0f, 0.0f, 0.0f,  1.0f,  1.0f,  1.0f, 1.0f},
@@ -27,3 +25,4 @@ TEST(Objective, DeclareUnifiedTest(HingeObj)) {
 
   ASSERT_NO_THROW(obj->DefaultEvalMetric());
 }
+}  // namespace xgboost

tests/cpp/objective/test_multiclass_obj.cc

@@ -9,7 +9,7 @@
 namespace xgboost {
 
 TEST(Objective, DeclareUnifiedTest(SoftmaxMultiClassObjGPair)) {
-  Context ctx = CreateEmptyGenericParam(GPUIDX);
+  Context ctx = MakeCUDACtx(GPUIDX);
   std::vector<std::pair<std::string, std::string>> args {{"num_class", "3"}};
   std::unique_ptr<ObjFunction> obj {
     ObjFunction::Create("multi:softmax", &ctx)
@@ -36,7 +36,7 @@ TEST(Objective, DeclareUnifiedTest(SoftmaxMultiClassObjGPair)) {
 }
 
 TEST(Objective, DeclareUnifiedTest(SoftmaxMultiClassBasic)) {
-  auto ctx = CreateEmptyGenericParam(GPUIDX);
+  auto ctx = MakeCUDACtx(GPUIDX);
   std::vector<std::pair<std::string, std::string>> args{
       std::pair<std::string, std::string>("num_class", "3")};
 
@@ -57,7 +57,7 @@ TEST(Objective, DeclareUnifiedTest(SoftmaxMultiClassBasic)) {
 }
 
 TEST(Objective, DeclareUnifiedTest(SoftprobMultiClassBasic)) {
-  Context ctx = CreateEmptyGenericParam(GPUIDX);
+  Context ctx = MakeCUDACtx(GPUIDX);
   std::vector<std::pair<std::string, std::string>> args {
     std::pair<std::string, std::string>("num_class", "3")};
 

tests/cpp/objective/test_quantile_obj.cc

@@ -10,11 +10,11 @@
 #include <memory>               // std::unique_ptr
 #include <vector>               // std::vector
 
-#include "../helpers.h"         // CheckConfigReload,CreateEmptyGenericParam,DeclareUnifiedTest
+#include "../helpers.h"         // CheckConfigReload,MakeCUDACtx,DeclareUnifiedTest
 
 namespace xgboost {
 TEST(Objective, DeclareUnifiedTest(Quantile)) {
-  Context ctx = CreateEmptyGenericParam(GPUIDX);
+  Context ctx = MakeCUDACtx(GPUIDX);
 
   {
     Args args{{"quantile_alpha", "[0.6, 0.8]"}};
@@ -37,7 +37,7 @@ TEST(Objective, DeclareUnifiedTest(Quantile)) {
 }
 
 TEST(Objective, DeclareUnifiedTest(QuantileIntercept)) {
-  Context ctx = CreateEmptyGenericParam(GPUIDX);
+  Context ctx = MakeCUDACtx(GPUIDX);
   Args args{{"quantile_alpha", "[0.6, 0.8]"}};
   std::unique_ptr<ObjFunction> obj{ObjFunction::Create("reg:quantileerror", &ctx)};
   obj->Configure(args);

tests/cpp/objective/test_regression_obj.cc

@@ -17,7 +17,7 @@
 namespace xgboost {
 
 TEST(Objective, DeclareUnifiedTest(LinearRegressionGPair)) {
-  Context ctx = CreateEmptyGenericParam(GPUIDX);
+  Context ctx = MakeCUDACtx(GPUIDX);
   std::vector<std::pair<std::string, std::string>> args;
 
   std::unique_ptr<ObjFunction> obj{ObjFunction::Create("reg:squarederror", &ctx)};
@@ -39,7 +39,7 @@ TEST(Objective, DeclareUnifiedTest(LinearRegressionGPair)) {
 }
 
 TEST(Objective, DeclareUnifiedTest(SquaredLog)) {
-  Context ctx = CreateEmptyGenericParam(GPUIDX);
+  Context ctx = MakeCUDACtx(GPUIDX);
   std::vector<std::pair<std::string, std::string>> args;
 
   std::unique_ptr<ObjFunction> obj{ObjFunction::Create("reg:squaredlogerror", &ctx)};
@@ -62,7 +62,7 @@ TEST(Objective, DeclareUnifiedTest(SquaredLog)) {
 }
 
 TEST(Objective, DeclareUnifiedTest(PseudoHuber)) {
-  Context ctx = CreateEmptyGenericParam(GPUIDX);
+  Context ctx = MakeCUDACtx(GPUIDX);
   Args args;
 
   std::unique_ptr<ObjFunction> obj{ObjFunction::Create("reg:pseudohubererror", &ctx)};
@@ -91,7 +91,7 @@ TEST(Objective, DeclareUnifiedTest(PseudoHuber)) {
 }
 
 TEST(Objective, DeclareUnifiedTest(LogisticRegressionGPair)) {
-  Context ctx = CreateEmptyGenericParam(GPUIDX);
+  Context ctx = MakeCUDACtx(GPUIDX);
   std::vector<std::pair<std::string, std::string>> args;
   std::unique_ptr<ObjFunction> obj{ObjFunction::Create("reg:logistic", &ctx)};
 
@@ -107,7 +107,7 @@ TEST(Objective, DeclareUnifiedTest(LogisticRegressionGPair)) {
 }
 
 TEST(Objective, DeclareUnifiedTest(LogisticRegressionBasic)) {
-  Context ctx = CreateEmptyGenericParam(GPUIDX);
+  Context ctx = MakeCUDACtx(GPUIDX);
   std::vector<std::pair<std::string, std::string>> args;
   std::unique_ptr<ObjFunction> obj{ObjFunction::Create("reg:logistic", &ctx)};
 
@@ -136,7 +136,7 @@ TEST(Objective, DeclareUnifiedTest(LogisticRegressionBasic)) {
 }
 
 TEST(Objective, DeclareUnifiedTest(LogisticRawGPair)) {
-  Context ctx = CreateEmptyGenericParam(GPUIDX);
+  Context ctx = MakeCUDACtx(GPUIDX);
   std::vector<std::pair<std::string, std::string>> args;
   std::unique_ptr<ObjFunction>  obj {
     ObjFunction::Create("binary:logitraw", &ctx)
@@ -152,7 +152,7 @@ TEST(Objective, DeclareUnifiedTest(LogisticRawGPair)) {
 }
 
 TEST(Objective, DeclareUnifiedTest(PoissonRegressionGPair)) {
-  Context ctx = CreateEmptyGenericParam(GPUIDX);
+  Context ctx = MakeCUDACtx(GPUIDX);
   std::vector<std::pair<std::string, std::string>> args;
   std::unique_ptr<ObjFunction> obj {
     ObjFunction::Create("count:poisson", &ctx)
@@ -176,7 +176,7 @@ TEST(Objective, DeclareUnifiedTest(PoissonRegressionGPair)) {
 }
 
 TEST(Objective, DeclareUnifiedTest(PoissonRegressionBasic)) {
-  Context ctx = CreateEmptyGenericParam(GPUIDX);
+  Context ctx = MakeCUDACtx(GPUIDX);
   std::vector<std::pair<std::string, std::string>> args;
   std::unique_ptr<ObjFunction> obj {
     ObjFunction::Create("count:poisson", &ctx)
@@ -205,7 +205,7 @@ TEST(Objective, DeclareUnifiedTest(PoissonRegressionBasic)) {
 }
 
 TEST(Objective, DeclareUnifiedTest(GammaRegressionGPair)) {
-  Context ctx = CreateEmptyGenericParam(GPUIDX);
+  Context ctx = MakeCUDACtx(GPUIDX);
   std::vector<std::pair<std::string, std::string>> args;
   std::unique_ptr<ObjFunction> obj {
     ObjFunction::Create("reg:gamma", &ctx)
@@ -227,7 +227,7 @@ TEST(Objective, DeclareUnifiedTest(GammaRegressionGPair)) {
 }
 
 TEST(Objective, DeclareUnifiedTest(GammaRegressionBasic)) {
-  Context ctx = CreateEmptyGenericParam(GPUIDX);
+  Context ctx = MakeCUDACtx(GPUIDX);
   std::vector<std::pair<std::string, std::string>> args;
   std::unique_ptr<ObjFunction> obj{ObjFunction::Create("reg:gamma", &ctx)};
 
@@ -256,7 +256,7 @@ TEST(Objective, DeclareUnifiedTest(GammaRegressionBasic)) {
 }
 
 TEST(Objective, DeclareUnifiedTest(TweedieRegressionGPair)) {
-  Context ctx = CreateEmptyGenericParam(GPUIDX);
+  Context ctx = MakeCUDACtx(GPUIDX);
   std::vector<std::pair<std::string, std::string>> args;
   std::unique_ptr<ObjFunction> obj{ObjFunction::Create("reg:tweedie", &ctx)};
 
@@ -280,7 +280,7 @@ TEST(Objective, DeclareUnifiedTest(TweedieRegressionGPair)) {
 
 #if defined(__CUDACC__)
 TEST(Objective, CPU_vs_CUDA) {
-  Context ctx = CreateEmptyGenericParam(GPUIDX);
+  Context ctx = MakeCUDACtx(GPUIDX);
 
   ObjFunction* obj = ObjFunction::Create("reg:squarederror", &ctx);
   HostDeviceVector<GradientPair> cpu_out_preds;
@@ -331,7 +331,7 @@ TEST(Objective, CPU_vs_CUDA) {
 #endif
 
 TEST(Objective, DeclareUnifiedTest(TweedieRegressionBasic)) {
-  Context ctx = CreateEmptyGenericParam(GPUIDX);
+  Context ctx = MakeCUDACtx(GPUIDX);
   std::vector<std::pair<std::string, std::string>> args;
   std::unique_ptr<ObjFunction> obj{ObjFunction::Create("reg:tweedie", &ctx)};
 
@@ -360,7 +360,7 @@ TEST(Objective, DeclareUnifiedTest(TweedieRegressionBasic)) {
 // CoxRegression not implemented in GPU code, no need for testing.
 #if !defined(__CUDACC__)
 TEST(Objective, CoxRegressionGPair) {
-  Context ctx = CreateEmptyGenericParam(GPUIDX);
+  Context ctx = MakeCUDACtx(GPUIDX);
   std::vector<std::pair<std::string, std::string>> args;
   std::unique_ptr<ObjFunction> obj{ObjFunction::Create("survival:cox", &ctx)};
 
@@ -375,7 +375,7 @@ TEST(Objective, CoxRegressionGPair) {
 #endif
 
 TEST(Objective, DeclareUnifiedTest(AbsoluteError)) {
-  Context ctx = CreateEmptyGenericParam(GPUIDX);
+  Context ctx = MakeCUDACtx(GPUIDX);
   std::unique_ptr<ObjFunction> obj{ObjFunction::Create("reg:absoluteerror", &ctx)};
   obj->Configure({});
   CheckConfigReload(obj, "reg:absoluteerror");
@@ -419,7 +419,7 @@ TEST(Objective, DeclareUnifiedTest(AbsoluteError)) {
 }
 
 TEST(Objective, DeclareUnifiedTest(AbsoluteErrorLeaf)) {
-  Context ctx = CreateEmptyGenericParam(GPUIDX);
+  Context ctx = MakeCUDACtx(GPUIDX);
   bst_target_t constexpr kTargets = 3, kRows = 16;
   std::unique_ptr<ObjFunction> obj{ObjFunction::Create("reg:absoluteerror", &ctx)};
   obj->Configure({});

tests/cpp/plugin/test_example_objective.cc

@@ -4,12 +4,10 @@
 #include "../helpers.h"
 
 namespace xgboost {
-
 TEST(Plugin, ExampleObjective) {
-  xgboost::Context ctx = CreateEmptyGenericParam(GPUIDX);
+  xgboost::Context ctx = MakeCUDACtx(GPUIDX);
   auto* obj = xgboost::ObjFunction::Create("mylogistic", &ctx);
   ASSERT_EQ(obj->DefaultEvalMetric(), std::string{"logloss"});
   delete obj;
 }
-
 }  // namespace xgboost

tests/cpp/plugin/test_predictor_oneapi.cc

@@ -12,7 +12,7 @@
 
 namespace xgboost {
 TEST(Plugin, OneAPIPredictorBasic) {
-  auto lparam = CreateEmptyGenericParam(0);
+  auto lparam = MakeCUDACtx(0);
   std::unique_ptr<Predictor> oneapi_predictor =
       std::unique_ptr<Predictor>(Predictor::Create("oneapi_predictor", &lparam));
 
@@ -82,7 +82,7 @@ TEST(Plugin, OneAPIPredictorExternalMemory) {
   dmlc::TemporaryDirectory tmpdir;
   std::string filename = tmpdir.path + "/big.libsvm";
   std::unique_ptr<DMatrix> dmat = CreateSparsePageDMatrix(12, 64, filename);
-  auto lparam = CreateEmptyGenericParam(0);
+  auto lparam = MakeCUDACtx(0);
 
   std::unique_ptr<Predictor> oneapi_predictor =
       std::unique_ptr<Predictor>(Predictor::Create("oneapi_predictor", &lparam));

tests/cpp/plugin/test_regression_obj_oneapi.cc

@@ -9,7 +9,7 @@
 namespace xgboost {
 
 TEST(Plugin, LinearRegressionGPairOneAPI) {
-  Context tparam = CreateEmptyGenericParam(0);
+  Context tparam = MakeCUDACtx(0);
   std::vector<std::pair<std::string, std::string>> args;
 
   std::unique_ptr<ObjFunction> obj {
@@ -33,7 +33,7 @@ TEST(Plugin, LinearRegressionGPairOneAPI) {
 }
 
 TEST(Plugin, SquaredLogOneAPI) {
-  Context tparam = CreateEmptyGenericParam(0);
+  Context tparam = MakeCUDACtx(0);
   std::vector<std::pair<std::string, std::string>> args;
 
   std::unique_ptr<ObjFunction> obj { ObjFunction::Create("reg:squaredlogerror_oneapi", &tparam) };
@@ -56,7 +56,7 @@ TEST(Plugin, SquaredLogOneAPI) {
 }
 
 TEST(Plugin, LogisticRegressionGPairOneAPI) {
-  Context tparam = CreateEmptyGenericParam(0);
+  Context tparam = MakeCUDACtx(0);
   std::vector<std::pair<std::string, std::string>> args;
   std::unique_ptr<ObjFunction> obj { ObjFunction::Create("reg:logistic_oneapi", &tparam) };
 
@@ -72,7 +72,7 @@ TEST(Plugin, LogisticRegressionGPairOneAPI) {
 }
 
 TEST(Plugin, LogisticRegressionBasicOneAPI) {
-  Context lparam = CreateEmptyGenericParam(0);
+  Context lparam = MakeCUDACtx(0);
   std::vector<std::pair<std::string, std::string>> args;
   std::unique_ptr<ObjFunction> obj {
     ObjFunction::Create("reg:logistic_oneapi", &lparam)
@@ -103,7 +103,7 @@ TEST(Plugin, LogisticRegressionBasicOneAPI) {
 }
 
 TEST(Plugin, LogisticRawGPairOneAPI) {
-  Context lparam = CreateEmptyGenericParam(0);
+  Context lparam = MakeCUDACtx(0);
   std::vector<std::pair<std::string, std::string>> args;
   std::unique_ptr<ObjFunction>  obj {
     ObjFunction::Create("binary:logitraw_oneapi", &lparam)
@@ -120,7 +120,7 @@ TEST(Plugin, LogisticRawGPairOneAPI) {
 }
 
 TEST(Plugin, CPUvsOneAPI) {
-  Context ctx = CreateEmptyGenericParam(0);
+  Context ctx = MakeCUDACtx(0);
 
   ObjFunction * obj_cpu =
       ObjFunction::Create("reg:squarederror", &ctx);
@@ -140,8 +140,8 @@ TEST(Plugin, CPUvsOneAPI) {
   }
   auto& info = pdmat->Info();
 
-  info.labels_.Resize(kRows);
+  info.labels.Reshape(kRows, 1);
-  auto& h_labels = info.labels_.HostVector();
+  auto& h_labels = info.labels.Data()->HostVector();
   for (size_t i = 0; i < h_labels.size(); ++i) {
     h_labels[i] = 1 / static_cast<float>(i+1);
   }

tests/cpp/predictor/test_cpu_predictor.cc

@@ -20,16 +20,15 @@ namespace xgboost {
 
 namespace {
 void TestBasic(DMatrix* dmat) {
-  auto lparam = CreateEmptyGenericParam(GPUIDX);
+  Context ctx;
   std::unique_ptr<Predictor> cpu_predictor =
-      std::unique_ptr<Predictor>(Predictor::Create("cpu_predictor", &lparam));
+      std::unique_ptr<Predictor>(Predictor::Create("cpu_predictor", &ctx));
 
   size_t const kRows = dmat->Info().num_row_;
   size_t const kCols = dmat->Info().num_col_;
 
   LearnerModelParam mparam{MakeMP(kCols, .0, 1)};
 
-  Context ctx;
   ctx.UpdateAllowUnknown(Args{});
   gbm::GBTreeModel model = CreateTestModel(&mparam, &ctx);
 

tests/cpp/predictor/test_gpu_predictor.cu

@@ -19,8 +19,8 @@ namespace xgboost {
 namespace predictor {
 
 TEST(GPUPredictor, Basic) {
-  auto cpu_lparam = CreateEmptyGenericParam(-1);
+  auto cpu_lparam = MakeCUDACtx(-1);
-  auto gpu_lparam = CreateEmptyGenericParam(0);
+  auto gpu_lparam = MakeCUDACtx(0);
 
   std::unique_ptr<Predictor> gpu_predictor =
       std::unique_ptr<Predictor>(Predictor::Create("gpu_predictor", &gpu_lparam));
@@ -84,7 +84,7 @@ TEST(GPUPredictor, EllpackTraining) {
 }
 
 TEST(GPUPredictor, ExternalMemoryTest) {
-  auto lparam = CreateEmptyGenericParam(0);
+  auto lparam = MakeCUDACtx(0);
   std::unique_ptr<Predictor> gpu_predictor =
       std::unique_ptr<Predictor>(Predictor::Create("gpu_predictor", &lparam));
   gpu_predictor->Configure({});
@@ -157,7 +157,7 @@ TEST(GPUPredictor, ShapStump) {
   trees.push_back(std::unique_ptr<RegTree>(new RegTree));
   model.CommitModelGroup(std::move(trees), 0);
 
-  auto gpu_lparam = CreateEmptyGenericParam(0);
+  auto gpu_lparam = MakeCUDACtx(0);
   std::unique_ptr<Predictor> gpu_predictor = std::unique_ptr<Predictor>(
       Predictor::Create("gpu_predictor", &gpu_lparam));
   gpu_predictor->Configure({});
@@ -185,8 +185,8 @@ TEST(GPUPredictor, Shap) {
   trees[0]->ExpandNode(0, 0, 0.5, true, 1.0, -1.0, 1.0, 0.0, 5.0, 2.0, 3.0);
   model.CommitModelGroup(std::move(trees), 0);
 
-  auto gpu_lparam = CreateEmptyGenericParam(0);
+  auto gpu_lparam = MakeCUDACtx(0);
-  auto cpu_lparam = CreateEmptyGenericParam(-1);
+  auto cpu_lparam = MakeCUDACtx(-1);
   std::unique_ptr<Predictor> gpu_predictor = std::unique_ptr<Predictor>(
       Predictor::Create("gpu_predictor", &gpu_lparam));
   std::unique_ptr<Predictor> cpu_predictor = std::unique_ptr<Predictor>(
@@ -220,7 +220,7 @@ TEST(GPUPredictor, CategoricalPredictLeaf) {
 TEST(GPUPredictor, PredictLeafBasic) {
   size_t constexpr kRows = 5, kCols = 5;
   auto dmat = RandomDataGenerator(kRows, kCols, 0).Device(0).GenerateDMatrix();
-  auto lparam = CreateEmptyGenericParam(GPUIDX);
+  auto lparam = MakeCUDACtx(GPUIDX);
   std::unique_ptr<Predictor> gpu_predictor =
       std::unique_ptr<Predictor>(Predictor::Create("gpu_predictor", &lparam));
   gpu_predictor->Configure({});

tests/cpp/predictor/test_predictor.h

@@ -37,10 +37,10 @@ void TestPredictionFromGradientIndex(std::string name, size_t rows, size_t cols,
   constexpr size_t kClasses { 3 };
 
   LearnerModelParam mparam{MakeMP(cols, .5, kClasses)};
-  auto lparam = CreateEmptyGenericParam(0);
+  auto cuda_ctx = MakeCUDACtx(0);
 
   std::unique_ptr<Predictor> predictor =
-      std::unique_ptr<Predictor>(Predictor::Create(name, &lparam));
+      std::unique_ptr<Predictor>(Predictor::Create(name, &cuda_ctx));
   predictor->Configure({});
 
   Context ctx;

tests/cpp/tree/hist/test_histogram.cc

@@ -25,7 +25,7 @@ void InitRowPartitionForTest(common::RowSetCollection *row_set, size_t n_samples
 }  // anonymous namespace
 
 void TestAddHistRows(bool is_distributed) {
-  auto ctx = CreateEmptyGenericParam(Context::kCpuId);
+  Context ctx;
   std::vector<CPUExpandEntry> nodes_for_explicit_hist_build_;
   std::vector<CPUExpandEntry> nodes_for_subtraction_trick_;
   int starting_index = std::numeric_limits<int>::max();
@@ -74,7 +74,7 @@ TEST(CPUHistogram, AddRows) {
 void TestSyncHist(bool is_distributed) {
   size_t constexpr kNRows = 8, kNCols = 16;
   int32_t constexpr kMaxBins = 4;
-  auto ctx = CreateEmptyGenericParam(Context::kCpuId);
+  Context ctx;
 
   std::vector<CPUExpandEntry> nodes_for_explicit_hist_build_;
   std::vector<CPUExpandEntry> nodes_for_subtraction_trick_;
@@ -229,7 +229,7 @@ TEST(CPUHistogram, SyncHist) {
 void TestBuildHistogram(bool is_distributed, bool force_read_by_column, bool is_col_split) {
   size_t constexpr kNRows = 8, kNCols = 16;
   int32_t constexpr kMaxBins = 4;
-  auto ctx = CreateEmptyGenericParam(Context::kCpuId);
+  Context ctx;
   auto p_fmat =
       RandomDataGenerator(kNRows, kNCols, 0.8).Seed(3).GenerateDMatrix();
   if (is_col_split) {
@@ -330,7 +330,7 @@ void TestHistogramCategorical(size_t n_categories, bool force_read_by_column) {
   auto x = GenerateRandomCategoricalSingleColumn(kRows, n_categories);
   auto cat_m = GetDMatrixFromData(x, kRows, 1);
   cat_m->Info().feature_types.HostVector().push_back(FeatureType::kCategorical);
-  auto ctx = CreateEmptyGenericParam(Context::kCpuId);
+  Context ctx;
 
   BatchParam batch_param{0, static_cast<int32_t>(kBins)};
 
@@ -475,7 +475,7 @@ void TestHistogramExternalMemory(Context const *ctx, BatchParam batch_param, boo
 
 TEST(CPUHistogram, ExternalMemory) {
   int32_t constexpr kBins = 256;
-  auto ctx = CreateEmptyGenericParam(Context::kCpuId);
+  Context ctx;
 
   TestHistogramExternalMemory(&ctx, BatchParam{kBins, common::Span<float>{}, false}, true, false);
   TestHistogramExternalMemory(&ctx, BatchParam{kBins, common::Span<float>{}, false}, true, true);

tests/cpp/tree/test_gpu_hist.cu

@@ -91,7 +91,7 @@ void TestBuildHist(bool use_shared_memory_histograms) {
 
   auto page = BuildEllpackPage(kNRows, kNCols);
   BatchParam batch_param{};
-  Context ctx{CreateEmptyGenericParam(0)};
+  Context ctx{MakeCUDACtx(0)};
   GPUHistMakerDevice<GradientSumT> maker(&ctx, page.get(), {}, kNRows, param, kNCols, kNCols,
                                          batch_param);
   xgboost::SimpleLCG gen;
@@ -169,7 +169,7 @@ void TestHistogramIndexImpl() {
   int constexpr kNRows = 1000, kNCols = 10;
 
   // Build 2 matrices and build a histogram maker with that
-  Context ctx(CreateEmptyGenericParam(0));
+  Context ctx(MakeCUDACtx(0));
   ObjInfo task{ObjInfo::kRegression};
   tree::GPUHistMaker hist_maker{&ctx, &task}, hist_maker_ext{&ctx, &task};
   std::unique_ptr<DMatrix> hist_maker_dmat(
@@ -262,7 +262,7 @@ TEST(GpuHist, UniformSampling) {
   // Build a tree using the in-memory DMatrix.
   RegTree tree;
   HostDeviceVector<bst_float> preds(kRows, 0.0, 0);
-  Context ctx(CreateEmptyGenericParam(0));
+  Context ctx(MakeCUDACtx(0));
   UpdateTree(&ctx, &gpair, dmat.get(), 0, &tree, &preds, 1.0, "uniform", kRows);
   // Build another tree using sampling.
   RegTree tree_sampling;
@@ -292,7 +292,7 @@ TEST(GpuHist, GradientBasedSampling) {
   // Build a tree using the in-memory DMatrix.
   RegTree tree;
   HostDeviceVector<bst_float> preds(kRows, 0.0, 0);
-  Context ctx(CreateEmptyGenericParam(0));
+  Context ctx(MakeCUDACtx(0));
   UpdateTree(&ctx, &gpair, dmat.get(), 0, &tree, &preds, 1.0, "uniform", kRows);
 
   // Build another tree using sampling.
@@ -327,7 +327,7 @@ TEST(GpuHist, ExternalMemory) {
 
   // Build a tree using the in-memory DMatrix.
   RegTree tree;
-  Context ctx(CreateEmptyGenericParam(0));
+  Context ctx(MakeCUDACtx(0));
   HostDeviceVector<bst_float> preds(kRows, 0.0, 0);
   UpdateTree(&ctx, &gpair, dmat.get(), 0, &tree, &preds, 1.0, "uniform", kRows);
   // Build another tree using multiple ELLPACK pages.
@@ -365,7 +365,7 @@ TEST(GpuHist, ExternalMemoryWithSampling) {
   // Build a tree using the in-memory DMatrix.
   auto rng = common::GlobalRandom();
 
-  Context ctx(CreateEmptyGenericParam(0));
+  Context ctx(MakeCUDACtx(0));
   RegTree tree;
   HostDeviceVector<bst_float> preds(kRows, 0.0, 0);
   UpdateTree(&ctx, &gpair, dmat.get(), 0, &tree, &preds, kSubsample, kSamplingMethod, kRows);
@@ -386,7 +386,7 @@ TEST(GpuHist, ExternalMemoryWithSampling) {
 }
 
 TEST(GpuHist, ConfigIO) {
-  Context ctx(CreateEmptyGenericParam(0));
+  Context ctx(MakeCUDACtx(0));
   ObjInfo task{ObjInfo::kRegression};
   std::unique_ptr<TreeUpdater> updater{TreeUpdater::Create("grow_gpu_hist", &ctx, &task)};
   updater->Configure(Args{});
@@ -404,7 +404,7 @@ TEST(GpuHist, ConfigIO) {
 }
 
 TEST(GpuHist, MaxDepth) {
-  Context ctx(CreateEmptyGenericParam(0));
+  Context ctx(MakeCUDACtx(0));
   size_t constexpr kRows = 16;
   size_t constexpr kCols = 4;
   auto p_mat = RandomDataGenerator{kRows, kCols, 0}.GenerateDMatrix();

tests/cpp/tree/test_prune.cc

@@ -29,7 +29,7 @@ TEST(Updater, Prune) {
   std::shared_ptr<DMatrix> p_dmat {
     RandomDataGenerator{32, 10, 0}.GenerateDMatrix() };
 
-  auto ctx = CreateEmptyGenericParam(GPUIDX);
+  Context ctx;
 
   // prepare tree
   RegTree tree = RegTree{1u, kCols};

tests/cpp/tree/test_refresh.cc

@@ -29,7 +29,7 @@ TEST(Updater, Refresh) {
       {"reg_lambda", "1"}};
 
   RegTree tree = RegTree{1u, kCols};
-  auto ctx = CreateEmptyGenericParam(GPUIDX);
+  Context ctx;
   std::vector<RegTree*> trees{&tree};
 
   ObjInfo task{ObjInfo::kRegression};

tests/cpp/tree/test_tree_stat.cc

@@ -33,8 +33,7 @@ class UpdaterTreeStatTest : public ::testing::Test {
     ObjInfo task{ObjInfo::kRegression};
     param.Init(Args{});
 
-    Context ctx(updater == "grow_gpu_hist" ? CreateEmptyGenericParam(0)
+    Context ctx(updater == "grow_gpu_hist" ? MakeCUDACtx(0) : MakeCUDACtx(Context::kCpuId));
-                                           : CreateEmptyGenericParam(Context::kCpuId));
     auto up = std::unique_ptr<TreeUpdater>{TreeUpdater::Create(updater, &ctx, &task)};
     up->Configure(Args{});
     RegTree tree{1u, kCols};
@@ -79,8 +78,7 @@ class UpdaterEtaTest : public ::testing::Test {
   void RunTest(std::string updater) {
     ObjInfo task{ObjInfo::kClassification};
 
-    Context ctx(updater == "grow_gpu_hist" ? CreateEmptyGenericParam(0)
+    Context ctx(updater == "grow_gpu_hist" ? MakeCUDACtx(0) : MakeCUDACtx(Context::kCpuId));
-                                           : CreateEmptyGenericParam(Context::kCpuId));
 
     float eta = 0.4;
     auto up_0 = std::unique_ptr<TreeUpdater>{TreeUpdater::Create(updater, &ctx, &task)};
@@ -156,8 +154,7 @@ class TestMinSplitLoss : public ::testing::Test {
     param.UpdateAllowUnknown(args);
     ObjInfo task{ObjInfo::kRegression};
 
-    Context ctx(updater == "grow_gpu_hist" ? CreateEmptyGenericParam(0)
+    Context ctx{MakeCUDACtx(updater == "grow_gpu_hist" ? 0 : Context::kCpuId)};
-                                           : CreateEmptyGenericParam(Context::kCpuId));
     auto up = std::unique_ptr<TreeUpdater>{TreeUpdater::Create(updater, &ctx, &task)};
     up->Configure({});