Fix for Java tests and replicate the test in C++

Signed-off-by: Muhammad Haseeb <14217455+mhaseeb123@users.noreply.github.com>

cpp/src/join/mixed_join_kernels_semi.cu

@@ -65,9 +65,11 @@ CUDF_KERNEL void __launch_bounds__(block_size)
     left_table, right_table, device_expression_data);
 
   if (outer_row_index < outer_num_rows) {
+    // Make sure to swap_tables here as hash_set will use probe table as the left one.
+    auto constexpr swap_tables = true;
     // Figure out the number of elements for this key.
     auto equality = single_expression_equality<has_nulls>{
-      evaluator, thread_intermediate_storage, false, equality_probe};
+      evaluator, thread_intermediate_storage, swap_tables, equality_probe};
 
     auto const set_ref_equality = set_ref.with_key_eq(equality);
     auto const result           = set_ref_equality.contains(tile, outer_row_index);

cpp/src/join/mixed_join_semi.cu

@@ -151,20 +151,16 @@ std::unique_ptr<rmm::device_uvector<size_type>> mixed_join_semi(
                                                             preprocessed_build_condtional};
   auto const equality_build_conditional =
     row_comparator_conditional_build.equal_to<false>(build_nulls, compare_nulls);
-  double_row_equality_comparator equality_build{equality_build_equality,
-                                                equality_build_conditional};
-
-  auto const build_num_rows = compute_hash_table_size(build.num_rows());
 
   hash_set_type row_set{
-    build_num_rows,
+    {compute_hash_table_size(build.num_rows())},
     cuco::empty_key{JoinNoneValue},
-    equality_build,
+    {equality_build_equality, equality_build_conditional},
     {row_hash_build.device_hasher(build_nulls)},
     {},
     {},
     cudf::detail::cuco_allocator<char>{rmm::mr::polymorphic_allocator<char>{}, stream},
-    stream.value()};
+    {stream.value()}};
 
   auto iter = thrust::make_counting_iterator(0);
 
@@ -183,12 +179,13 @@ std::unique_ptr<rmm::device_uvector<size_type>> mixed_join_semi(
 
   detail::grid_1d const config(outer_num_rows, DEFAULT_JOIN_BLOCK_SIZE);
   auto const shmem_size_per_block =
-    (parser.shmem_per_thread / hash_set_type::cg_size) * config.num_threads_per_block;
+    parser.shmem_per_thread *
+    cuco::detail::int_div_ceil(config.num_threads_per_block, hash_set_type::cg_size);
 
-  auto const row_hash = cudf::experimental::row::hash::row_hasher{preprocessed_probe};
+  auto const row_hash   = cudf::experimental::row::hash::row_hasher{preprocessed_probe};
+  auto const hash_probe = row_hash.device_hasher(has_nulls);
 
-  hash_set_ref_type const row_set_ref =
-    row_set.ref(cuco::contains).with_hash_function(row_hash.device_hasher(has_nulls));
+  hash_set_ref_type const row_set_ref = row_set.ref(cuco::contains).with_hash_function(hash_probe);
 
   // Vector used to indicate indices from left/probe table which are present in output
   auto left_table_keep_mask = rmm::device_uvector<bool>(probe.num_rows(), stream);

cpp/tests/join/mixed_join_tests.cu

@@ -778,6 +778,21 @@ TYPED_TEST(MixedLeftSemiJoinTest, BasicEquality)
              {1});
 }
 
+TYPED_TEST(MixedLeftSemiJoinTest, MixedLeftSemiJoinGatherMap)
+{
+  auto const col_ref_left_1  = cudf::ast::column_reference(0, cudf::ast::table_reference::LEFT);
+  auto const col_ref_right_1 = cudf::ast::column_reference(0, cudf::ast::table_reference::RIGHT);
+  auto left_one_greater_right_one =
+    cudf::ast::operation(cudf::ast::ast_operator::GREATER, col_ref_left_1, col_ref_right_1);
+
+  this->test({{2, 3, 9, 0, 1, 7, 4, 6, 5, 8}, {1, 2, 3, 4, 5, 6, 7, 8, 9, 0}},
+             {{6, 5, 9, 8, 10, 32}, {0, 1, 2, 3, 4, 5}, {7, 8, 9, 0, 1, 2}},
+             {0},
+             {1},
+             left_one_greater_right_one,
+             {2, 7, 8});
+}
+
 TYPED_TEST(MixedLeftSemiJoinTest, BasicEqualityDuplicates)
 {
   this->test({{0, 1, 2, 1}, {3, 4, 5, 6}, {10, 20, 30, 40}},