Add rewrite to remove Blockwise of AdvancedIncSubtensor

Author: ricardoV94

pytensor/tensor/rewriting/subtensor.py

@@ -29,6 +29,7 @@
     register_infer_shape,
     switch,
 )
+from pytensor.tensor.blockwise import Blockwise
 from pytensor.tensor.elemwise import Elemwise
 from pytensor.tensor.exceptions import NotScalarConstantError
 from pytensor.tensor.math import Dot, add
@@ -1880,3 +1881,58 @@ def local_uint_constant_indices(fgraph, node):
     copy_stack_trace(node.outputs, new_outs)
 
     return new_outs
+
+
+@register_canonicalize("shape_unsafe")
+@register_stabilize("shape_unsafe")
+@register_specialize("shape_unsafe")
+@node_rewriter([Blockwise])
+def local_blockwise_advanced_inc_subtensor(fgraph, node):
+    """Rewrite blockwise advanced inc_subtensor whithout batched indexes as an inc_subtensor with prepended empty slices."""
+    if not isinstance(node.op.core_op, AdvancedIncSubtensor):
+        return None
+
+    x, y, *idxs = node.inputs
+
+    # It is currently not possible to Vectorize such AdvancedIncSubtensor, but we check again just in case
+    if any(
+        (
+            isinstance(idx, (SliceType, NoneTypeT))
+            or (idx.type.dtype == "bool" and idx.type.ndim > 0)
+        )
+        for idx in idxs
+    ):
+        return None
+
+    op: Blockwise = node.op  # type: ignore
+    batch_ndim = op.batch_ndim(node)
+
+    new_idxs = []
+    for idx in idxs:
+        if all(idx.type.broadcastable[:batch_ndim]):
+            new_idxs.append(idx.squeeze(tuple(range(batch_ndim))))
+        else:
+            # Rewrite does not apply
+            return None
+
+    x_batch_bcast = x.type.broadcastable[:batch_ndim]
+    y_batch_bcast = y.type.broadcastable[:batch_ndim]
+    if any(xb and not yb for xb, yb in zip(x_batch_bcast, y_batch_bcast)):
+        # Need to broadcast batch x dims
+        batch_shape = tuple(
+            x_dim if (not xb or yb) else y_dim
+            for xb, x_dim, yb, y_dim in zip(
+                x_batch_bcast,
+                tuple(x.shape)[:batch_ndim],
+                y_batch_bcast,
+                tuple(y.shape)[:batch_ndim],
+            )
+        )
+        core_shape = tuple(x.shape)[batch_ndim:]
+        x = alloc(x, *batch_shape, *core_shape)
+
+    new_idxs = [slice(None)] * batch_ndim + new_idxs
+    symbolic_idxs = x[tuple(new_idxs)].owner.inputs[1:]
+    new_out = op.core_op.make_node(x, y, *symbolic_idxs).outputs
+    copy_stack_trace(node.outputs, new_out)
+    return new_out

tests/tensor/rewriting/test_subtensor.py

@@ -9,7 +9,7 @@
 from pytensor.compile.mode import Mode, get_default_mode, get_mode
 from pytensor.compile.ops import DeepCopyOp
 from pytensor.configdefaults import config
-from pytensor.graph import FunctionGraph
+from pytensor.graph import FunctionGraph, vectorize_graph
 from pytensor.graph.basic import Constant, Variable, ancestors
 from pytensor.graph.rewriting.basic import check_stack_trace
 from pytensor.graph.rewriting.db import RewriteDatabaseQuery
@@ -18,6 +18,7 @@
 from pytensor.raise_op import Assert
 from pytensor.tensor import inplace
 from pytensor.tensor.basic import Alloc, MakeVector, _convert_to_int8, make_vector
+from pytensor.tensor.blockwise import Blockwise
 from pytensor.tensor.elemwise import DimShuffle, Elemwise
 from pytensor.tensor.math import Dot, add, dot, exp, sqr
 from pytensor.tensor.rewriting.subtensor import (
@@ -2314,3 +2315,105 @@ def test_local_uint_constant_indices():
     new_index = subtensor_node.inputs[1]
     assert isinstance(new_index, Constant)
     assert new_index.type.dtype == "uint8"
+
+
+@pytest.mark.parametrize("set_instead_of_inc", (True, False))
+def test_local_blockwise_advanced_inc_subtensor(set_instead_of_inc):
+    core_x = tensor("x", shape=(6,))
+    core_y = tensor("y", shape=(3,))
+    core_idxs = [0, 2, 4]
+    if set_instead_of_inc:
+        core_graph = set_subtensor(core_x[core_idxs], core_y)
+    else:
+        core_graph = inc_subtensor(core_x[core_idxs], core_y)
+
+    # Only x is batched
+    x = tensor(
+        "x",
+        shape=(
+            5,
+            2,
+            6,
+        ),
+    )
+    y = tensor("y", shape=(3,))
+    out = vectorize_graph(core_graph, replace={core_x: x, core_y: y})
+    assert isinstance(out.owner.op, Blockwise)
+
+    fn = pytensor.function([x, y], out, mode="FAST_RUN")
+    assert not any(
+        isinstance(node.op, Blockwise) for node in fn.maker.fgraph.apply_nodes
+    )
+
+    test_x = np.ones(x.type.shape, dtype=x.type.dtype)
+    test_y = np.array([5, 6, 7]).astype(dtype=core_y.type.dtype)
+    expected_out = test_x.copy()
+    if set_instead_of_inc:
+        expected_out[:, :, core_idxs] = test_y
+    else:
+        expected_out[:, :, core_idxs] += test_y
+    np.testing.assert_allclose(fn(test_x, test_y), expected_out)
+
+    # Only y is batched
+    x = tensor("y", shape=(6,))
+    y = tensor("y", shape=(2, 3))
+    out = vectorize_graph(core_graph, replace={core_x: x, core_y: y})
+    assert isinstance(out.owner.op, Blockwise)
+
+    fn = pytensor.function([x, y], out, mode="FAST_RUN")
+    assert not any(
+        isinstance(node.op, Blockwise) for node in fn.maker.fgraph.apply_nodes
+    )
+
+    test_x = np.ones(x.type.shape, dtype=x.type.dtype)
+    test_y = np.array([[3, 3, 3], [5, 6, 7]]).astype(dtype=core_y.type.dtype)
+    expected_out = np.ones((2, *x.type.shape))
+    if set_instead_of_inc:
+        expected_out[:, core_idxs] = test_y
+    else:
+        expected_out[:, core_idxs] += test_y
+    np.testing.assert_allclose(fn(test_x, test_y), expected_out)
+
+    # Both x and y are batched, and do not need to be broadcasted
+    x = tensor("y", shape=(2, 6))
+    y = tensor("y", shape=(2, 3))
+    out = vectorize_graph(core_graph, replace={core_x: x, core_y: y})
+    assert isinstance(out.owner.op, Blockwise)
+
+    fn = pytensor.function([x, y], out, mode="FAST_RUN")
+    assert not any(
+        isinstance(node.op, Blockwise) for node in fn.maker.fgraph.apply_nodes
+    )
+
+    test_x = np.ones(x.type.shape, dtype=x.type.dtype)
+    test_y = np.array([[5, 6, 7], [3, 3, 3]]).astype(dtype=core_y.type.dtype)
+    expected_out = test_x.copy()
+    if set_instead_of_inc:
+        expected_out[:, core_idxs] = test_y
+    else:
+        expected_out[:, core_idxs] += test_y
+    np.testing.assert_allclose(fn(test_x, test_y), expected_out)
+
+    # Both x and y are batched, but must be broadcasted
+    x = tensor("y", shape=(5, 1, 6))
+    y = tensor("y", shape=(1, 2, 3))
+    out = vectorize_graph(core_graph, replace={core_x: x, core_y: y})
+    assert isinstance(out.owner.op, Blockwise)
+
+    fn = pytensor.function([x, y], out, mode="FAST_RUN")
+    assert not any(
+        isinstance(node.op, Blockwise) for node in fn.maker.fgraph.apply_nodes
+    )
+
+    test_x = np.ones(x.type.shape, dtype=x.type.dtype)
+    test_y = np.array([[[5, 6, 7], [3, 3, 3]]]).astype(dtype=core_y.type.dtype)
+    final_shape = (
+        *np.broadcast_shapes(x.type.shape[:-1], y.type.shape[:-1]),
+        x.type.shape[-1],
+    )
+    expected_out = np.broadcast_to(test_x, final_shape).copy()
+    if set_instead_of_inc:
+        expected_out[:, :, core_idxs] = test_y
+    else:
+        expected_out[:, :, core_idxs] += test_y
+    np.testing.assert_allclose(fn(test_x, test_y), expected_out)