Allow Blockwise to create dummy core nodes with outer inputs, if these are unbatched

Author: ricardoV94

pytensor/link/jax/dispatch/blockwise.py

@@ -1,24 +1,16 @@
 import jax.numpy as jnp
 
-from pytensor.graph import FunctionGraph
 from pytensor.link.jax.dispatch import jax_funcify
 from pytensor.tensor.blockwise import Blockwise
 
 
 @jax_funcify.register(Blockwise)
-def funcify_Blockwise(op: Blockwise, node, *args, **kwargs):
+def jax_funcify_Blockwise(op: Blockwise, node, **kwargs):
     signature = op.signature
-    core_node = op._create_dummy_core_node(node.inputs)
-    core_fgraph = FunctionGraph(inputs=core_node.inputs, outputs=core_node.outputs)
-    tuple_core_fn = jax_funcify(core_fgraph)
-
-    if len(node.outputs) == 1:
-
-        def core_fn(*inputs):
-            return tuple_core_fn(*inputs)[0]
-
-    else:
-        core_fn = tuple_core_fn
+    core_node = op._create_dummy_core_node(
+        node.inputs, propagate_unbatched_core_inputs=True
+    )
+    core_fn = jax_funcify(core_node.op, node=core_node, **kwargs)
 
     vect_fn = jnp.vectorize(core_fn, signature=signature)
 

pytensor/link/numba/dispatch/blockwise.py

@@ -16,7 +16,7 @@
 from pytensor.tensor.blockwise import Blockwise, BlockwiseWithCoreShape
 
 
-@numba_funcify.register
+@numba_funcify.register(BlockwiseWithCoreShape)
 def numba_funcify_Blockwise(op: BlockwiseWithCoreShape, node, **kwargs):
     [blockwise_node] = op.fgraph.apply_nodes
     blockwise_op: Blockwise = blockwise_node.op
@@ -26,7 +26,8 @@ def numba_funcify_Blockwise(op: BlockwiseWithCoreShape, node, **kwargs):
     core_shapes_len = tuple(get_vector_length(sh) for sh in node.inputs[nin:])
 
     core_node = blockwise_op._create_dummy_core_node(
-        cast(tuple[TensorVariable], blockwise_node.inputs)
+        cast(tuple[TensorVariable], node.inputs[:nin]),
+        propagate_unbatched_core_inputs=True,
     )
     core_op_fn = numba_funcify(
         core_op,

pytensor/tensor/blockwise.py

@@ -32,6 +32,17 @@
 from pytensor.tensor.variable import TensorVariable
 
 
+def _squeeze_left(x, stop_at_dim: int | None = None):
+    """Squeeze any leading dims of `x` until a real dim or `stop_at_dim` (if not None) is reached."""
+    x_dims = x.type.broadcastable
+    squeeze_ndim = len(x_dims) if all(x_dims) else x_dims.index(False)
+    if stop_at_dim is not None:
+        squeeze_ndim = min(squeeze_ndim, stop_at_dim)
+    if squeeze_ndim == 0:
+        return x
+    return x.squeeze(axis=tuple(range(squeeze_ndim)))
+
+
 def _vectorize_node_perform(
     core_node: Apply,
     batch_bcast_patterns: Sequence[tuple[bool, ...]],
@@ -143,8 +154,6 @@ def _check_runtime_broadcast_core(numerical_inputs, batch_bcast_patterns, batch_
 class Blockwise(COp):
     """Generalizes a core `Op` to work with batched dimensions.
 
-    TODO: Dispatch JAX (should be easy with the vectorize macro)
-    TODO: Dispatch Numba
     TODO: C implementation?
     TODO: Fuse Blockwise?
     """
@@ -202,21 +211,33 @@ def __init__(
 
         super().__init__(**kwargs)
 
-    def _create_dummy_core_node(self, inputs: Sequence[TensorVariable]) -> Apply:
-        core_input_types = []
+    def _create_dummy_core_node(
+        self,
+        inputs: Sequence[TensorVariable],
+        propagate_unbatched_core_inputs: bool = False,
+        return_dummy_inputs: bool = False,
+    ) -> Apply:
+        core_inputs = []
+        core_dummy_inputs = []
         for i, (inp, sig) in enumerate(zip(inputs, self.inputs_sig, strict=True)):
             if inp.type.ndim < len(sig):
                 raise ValueError(
                     f"Input {i} {inp} has insufficient core dimensions for signature {self.signature}"
                 )
             # ndim_supp = 0 case
-            if not sig:
-                core_shape = ()
+            inp_ndim = inp.type.ndim
+            batch_ndim = inp_ndim - len(sig)
+            core_shape = inp.type.shape[batch_ndim:]
+            if propagate_unbatched_core_inputs and all(
+                inp.type.broadcastable[:batch_ndim]
+            ):
+                core_inputs.append(_squeeze_left(inp, batch_ndim))
             else:
-                core_shape = inp.type.shape[-len(sig) :]
-            core_input_types.append(tensor(dtype=inp.type.dtype, shape=core_shape))
+                dummy_inp = tensor(dtype=inp.type.dtype, shape=core_shape)
+                core_inputs.append(dummy_inp)
+                core_dummy_inputs.append(dummy_inp)
 
-        core_node = self.core_op.make_node(*core_input_types)
+        core_node = self.core_op.make_node(*core_inputs)
 
         if len(core_node.outputs) != len(self.outputs_sig):
             raise ValueError(
@@ -230,6 +251,9 @@ def _create_dummy_core_node(self, inputs: Sequence[TensorVariable]) -> Apply:
                     f"Output {i} of {self.core_op} has wrong number of core dimensions for signature {self.signature}: {core_out.type.ndim}"
                 )
 
+        if return_dummy_inputs:
+            return core_node, core_dummy_inputs
+
         return core_node
 
     def make_node(self, *inputs):
@@ -298,11 +322,17 @@ def infer_shape(
 
         batch_shape = broadcast_shape(*batch_shapes, arrays_are_shapes=True)
 
-        # Try to extract the core shapes from the core_op
-        core_op_infer_shape = getattr(self.core_op, "infer_shape", None)
-        if core_op_infer_shape is not None:
-            dummy_core_node = self._create_dummy_core_node(node.inputs)
-            dummy_core_inputs = tuple(explicit_graph_inputs(dummy_core_node.inputs))
+        def extract_core_shape_from_infer_shape():
+            # Try to extract the core shapes from the core_op
+            core_op_infer_shape = getattr(self.core_op, "infer_shape", None)
+            if core_op_infer_shape is None:
+                return [[None] * out.ndim for out in node.outputs]
+
+            dummy_core_node, dummy_core_inputs = self._create_dummy_core_node(
+                node.inputs,
+                return_dummy_inputs=True,
+                propagate_unbatched_core_inputs=True,
+            )
             dummy_fgraph = FunctionGraph(outputs=dummy_core_node.outputs, clone=False)
             core_input_shapes = [
                 input_shape[batch_ndims:] for input_shape in input_shapes
@@ -311,6 +341,25 @@ def infer_shape(
                 dummy_fgraph, dummy_core_node, core_input_shapes
             )
 
+            # Set to None those core_shapes that depend on dummy_core_inputs,
+            # meaning their value may not be constant across batch dims of the Blockwise
+            if not dummy_core_inputs:
+                # All inputs are unbatched, so the core_shape can be used as is
+                return core_output_shapes
+            else:
+                set_dummy_core_inputs = set(dummy_core_inputs)
+                safe_core_output_shapes = [list(shape) for shape in core_output_shapes]
+                for core_out_shape in safe_core_output_shapes:
+                    for o, core_out_dim in enumerate(core_out_shape):
+                        if set_dummy_core_inputs & set(
+                            explicit_graph_inputs([core_out_dim])
+                        ):
+                            core_out_shape[o] = None
+
+                return safe_core_output_shapes
+
+        safe_core_out_shape = None
+
         out_shapes = []
         for o, (output, sig) in enumerate(
             zip(node.outputs, self.outputs_sig, strict=True)
@@ -321,19 +370,15 @@ def infer_shape(
                 if dim_name in core_dims:
                     core_out_shape.append(core_dims[dim_name])
                 else:
-                    if core_op_infer_shape is not None:
-                        # If the input values are needed to compute the dimension length, we can't use the infer_shape
-                        # of the core_node as the value is not constant across batch dims of the Blockwise
-                        core_out_dim = core_output_shapes[o][i]
-                        if not (
-                            set(dummy_core_inputs)
-                            & set(explicit_graph_inputs([core_out_dim]))
-                        ):
-                            core_out_shape.append(core_out_dim)
-                            continue
-
-                    # Fallback shape requires evaluating the Blockwise Op
-                    core_out_shape.append(Shape_i(batch_ndims + i)(output))
+                    if safe_core_out_shape is None:
+                        # Extract the core shape from the core_op infer_shape on demand
+                        # For many Ops we never need to do this, because all info is in their signature
+                        safe_core_out_shape = extract_core_shape_from_infer_shape()
+                    if (core_out_dim := safe_core_out_shape[o][i]) is not None:
+                        core_out_shape.append(core_out_dim)
+                    else:
+                        # Fallback shape requires evaluating the Blockwise Op
+                        core_out_shape.append(Shape_i(batch_ndims + i)(output))
             out_shapes.append((*batch_shape, *core_out_shape))
 
         return out_shapes
@@ -448,7 +493,9 @@ def gufunc(
                     )
                     return core_func(*inputs)
         else:
-            core_node = self._create_dummy_core_node(node.inputs)  # type: ignore
+            core_node = self._create_dummy_core_node(
+                node.inputs, propagate_unbatched_core_inputs=True
+            )  # type: ignore
             gufunc = _vectorize_node_perform(
                 core_node,
                 batch_bcast_patterns=batch_bcast_patterns,

pytensor/tensor/rewriting/blockwise.py

@@ -4,7 +4,7 @@
 from pytensor.graph.replace import vectorize_node
 from pytensor.graph.rewriting.basic import copy_stack_trace, out2in
 from pytensor.tensor.basic import Alloc, ARange, alloc, shape_padleft
-from pytensor.tensor.blockwise import Blockwise
+from pytensor.tensor.blockwise import Blockwise, _squeeze_left
 from pytensor.tensor.math import Dot
 from pytensor.tensor.rewriting.basic import (
     register_canonicalize,
@@ -90,17 +90,6 @@ def local_eager_useless_unbatched_blockwise(fgraph, node):
         return local_useless_unbatched_blockwise.fn(fgraph, node)
 
 
-def _squeeze_left(x, stop_at_dim: int | None = None):
-    """Squeeze any leading dims of `x` until a real dim or `stop_at_dim` (if not None) is reached."""
-    x_dims = x.type.broadcastable
-    squeeze_ndim = len(x_dims) if all(x_dims) else x_dims.index(False)
-    if stop_at_dim is not None:
-        squeeze_ndim = min(squeeze_ndim, stop_at_dim)
-    if squeeze_ndim == 0:
-        return x
-    return x.squeeze(axis=tuple(range(squeeze_ndim)))
-
-
 @register_specialize("shape_unsafe")
 @node_rewriter([Blockwise])
 def local_blockwise_alloc(fgraph, node):