[MLIR] Scaffold MLIR based UDF backend

conda/recipes/cudf/recipe.yaml

@@ -91,6 +91,9 @@ requirements:
     - pandas >=3.0.0,<3.1.0
     - cupy >=13.6.0,!=14.0.0,!=14.1.0
     - numba-cuda >=0.22.2
+    # TODO: add `numba-cuda-mlir >=0.3.0` here once it is published to a conda
+    # channel. Currently only available via PyPI; the pip-only declaration
+    # lives in `dependencies.yaml::depends_on_numba_cuda_mlir`.
     - numba >=0.60.0,<0.65.0
     - numpy >=1.26,<3.0
     - pyarrow>=19.0.0

dependencies.yaml

@@ -26,6 +26,7 @@ files:
       - depends_on_librapidsmpf
       - depends_on_libucxx
       - depends_on_numba_cuda
+      - depends_on_numba_cuda_mlir
       - depends_on_rapids_logger
       - depends_on_rapidsmpf
       - depends_on_ray
@@ -90,6 +91,7 @@ files:
       - depends_on_pylibcudf
       - depends_on_libcudf
       - depends_on_numba_cuda
+      - depends_on_numba_cuda_mlir
   test_python_pylibcudf:
     output: none
     includes:
@@ -203,6 +205,7 @@ files:
       - depends_on_cupy
       - depends_on_libcudf
       - depends_on_numba_cuda
+      - depends_on_numba_cuda_mlir
       - depends_on_pylibcudf_pyarrow
       - depends_on_rmm
       - depends_on_cuda_python
@@ -1177,6 +1180,30 @@ dependencies:
           - matrix:
             packages:
               - *numba_cuda
+  depends_on_numba_cuda_mlir:
+    # numba-cuda-mlir is the MLIR-based numba-cuda compiler used by the cudf
+    # UDF backend. Currently only published to PyPI; conda packaging is a
+    # tracked feature request (see TODOs in conda/recipes/cudf/recipe.yaml).
+    # Once a conda package exists, add an `output_types: [conda]` entry here
+    # mirroring `depends_on_numba_cuda`.
+    specific:
+      - output_types: [requirements, pyproject]
+        matrices:
+          - matrix:
+              cuda: "12.*"
+              cuda_suffixed: "true"
+            packages:
+              - numba-cuda-mlir[cu12]>=0.3.0
+          - matrix:
+              cuda: "13.*"
+              cuda_suffixed: "true"
+            packages:
+              - numba-cuda-mlir[cu13]>=0.3.0
+          # fallback to numba-cuda-mlir with no extra CUDA packages if
+          # 'cuda_suffixed' isn't true
+          - matrix:
+            packages:
+              - numba-cuda-mlir>=0.3.0
   depends_on_pylibcudf:
     common:
       - output_types: conda

python/cudf/cudf/core/udf/mlir_backend/__init__.py

@@ -0,0 +1,3 @@
+# SPDX-FileCopyrightText: Copyright (c) 2026, NVIDIA CORPORATION.
+# SPDX-License-Identifier: Apache-2.0
+"""MLIR / numba_cuda_mlir UDF backend namespace, empty for now."""

python/cudf/cudf/tests/private_objects/mlir_backend/__init__.py

@@ -0,0 +1,2 @@
+# SPDX-FileCopyrightText: Copyright (c) 2026, NVIDIA CORPORATION.
+# SPDX-License-Identifier: Apache-2.0

python/cudf/cudf/tests/private_objects/mlir_backend/test_plumbing.py

@@ -0,0 +1,13 @@
+# SPDX-FileCopyrightText: Copyright (c) 2026, NVIDIA CORPORATION.
+# SPDX-License-Identifier: Apache-2.0
+import pytest
+
+pytest.importorskip("numba_cuda_mlir")
+
+
+def test_mlir_backend_package_importable():
+    import cudf.core.udf.mlir_backend as m
+
+    # Module is intentionally empty at this layer, only the docstring
+    # is present.
+    assert m.__doc__

python/cudf/pyproject.toml

@@ -24,6 +24,7 @@ dependencies = [
     "cupy-cuda13x>=13.6.0,!=14.0.0,!=14.1.0",
     "fsspec>=0.6.0",
     "libcudf==26.8.*,>=0.0.0a0",
+    "numba-cuda-mlir>=0.3.0",
     "numba-cuda>=0.22.2",
     "numba>=0.60.0,<0.65.0",
     "numpy>=1.26,<3.0",