refactor is_in_ancestors to support multiple inputs

pytensor/graph/basic.py

@@ -1568,15 +1568,15 @@ def list_of_nodes(
     )
 
 
-def is_in_ancestors(l_apply: Apply, f_apply: Apply) -> bool:
-    """Determine if `f_apply` is in the graph given by `l_apply`.
+def apply_depends_on(apply: Apply, depends_on: Union[Apply, Collection[Apply]]) -> bool:
+    """Determine if any `depends_on` is in the graph given by ``apply``.
 
     Parameters
     ----------
-    l_apply : Apply
-        The node to walk.
-    f_apply : Apply
-        The node to find in `l_apply`.
+    apply : Apply
+        The Apply node to check.
+    depends_on : Union[Apply, Collection[Apply]]
+        Apply nodes to check dependency on
 
     Returns
     -------
@@ -1584,14 +1584,18 @@ def is_in_ancestors(l_apply: Apply, f_apply: Apply) -> bool:
 
     """
     computed = set()
-    todo = [l_apply]
+    todo = [apply]
+    if not isinstance(depends_on, Collection):
+        depends_on = {depends_on}
+    else:
+        depends_on = set(depends_on)
     while todo:
         cur = todo.pop()
         if cur.outputs[0] in computed:
             continue
         if all(i in computed or i.owner is None for i in cur.inputs):
             computed.update(cur.outputs)
-            if cur is f_apply:
+            if cur in depends_on:
                 return True
         else:
             todo.append(cur)

pytensor/ifelse.py

@@ -20,7 +20,7 @@ import pytensor.tensor as at
 from pytensor import as_symbolic
 from pytensor.compile import optdb
 from pytensor.configdefaults import config
-from pytensor.graph.basic import Apply, Variable, is_in_ancestors
+from pytensor.graph.basic import Apply, Variable, apply_depends_on
 from pytensor.graph.op import _NoPythonOp
 from pytensor.graph.replace import clone_replace
 from pytensor.graph.rewriting.basic import GraphRewriter, in2out, node_rewriter
@@ -604,7 +604,7 @@ class CondMerge(GraphRewriter):
             return False
         merging_node = cond_nodes[0]
         for proposal in cond_nodes[1:]:
-            if proposal.inputs[0] == merging_node.inputs[0] and not is_in_ancestors(
+            if proposal.inputs[0] == merging_node.inputs[0] and not apply_depends_on(
                 proposal, merging_node
             ):
                 # Create a list of replacements for proposal
@@ -704,8 +704,8 @@ def cond_merge_random_op(fgraph, main_node):
     for proposal in cond_nodes[1:]:
         if (
             proposal.inputs[0] == merging_node.inputs[0]
-            and not is_in_ancestors(proposal, merging_node)
-            and not is_in_ancestors(merging_node, proposal)
+            and not apply_depends_on(proposal, merging_node)
+            and not apply_depends_on(merging_node, proposal)
         ):
             # Create a list of replacements for proposal
             mn_ts = merging_node.inputs[1:][: merging_node.op.n_outs]

pytensor/scan/rewriting.py

@@ -18,10 +18,10 @@ from pytensor.graph.basic import (
     Apply,
     Constant,
     Variable,
+    apply_depends_on,
     equal_computations,
     graph_inputs,
     io_toposort,
-    is_in_ancestors,
 )
 from pytensor.graph.destroyhandler import DestroyHandler
 from pytensor.graph.features import ReplaceValidate
@@ -1642,7 +1642,7 @@ def save_mem_new_scan(fgraph, node):
                     old_new += [(o, new_outs[nw_pos])]
             # Check if the new outputs depend on the old scan node
             old_scan_is_used = [
-                is_in_ancestors(new.owner, node) for old, new in old_new
+                apply_depends_on(new.owner, node) for old, new in old_new
             ]
             if any(old_scan_is_used):
                 return False
@@ -1877,7 +1877,7 @@ class ScanMerge(GraphRewriter):
 
         # Check to see if it is an input of a different node
         for nd in set_nodes:
-            if is_in_ancestors(node, nd) or is_in_ancestors(nd, node):
+            if apply_depends_on(node, nd) or apply_depends_on(nd, node):
                 return False
 
         if not node.op.info.as_while:

tests/graph/test_basic.py

@@ -11,6 +11,7 @@ from pytensor.graph.basic import (
     NominalVariable,
     Variable,
     ancestors,
+    apply_depends_on,
     applys_between,
     as_string,
     clone,
@@ -20,7 +21,6 @@ from pytensor.graph.basic import (
     get_var_by_name,
     graph_inputs,
     io_toposort,
-    is_in_ancestors,
     list_of_nodes,
     orphans_between,
     vars_between,
@@ -491,15 +491,19 @@ def test_list_of_nodes():
     assert res == [o2.owner, o1.owner]
 
 
-def test_is_in_ancestors():
+def test_apply_depends_on():
 
     r1, r2, r3 = MyVariable(1), MyVariable(2), MyVariable(3)
     o1 = MyOp(r1, r2)
     o1.name = "o1"
-    o2 = MyOp(r3, o1)
+    o2 = MyOp(r1, o1)
     o2.name = "o2"
+    o3 = MyOp(r3, o1, o2)
+    o3.name = "o3"
 
-    assert is_in_ancestors(o2.owner, o1.owner)
+    assert apply_depends_on(o2.owner, o1.owner)
+    assert apply_depends_on(o2.owner, o2.owner)
+    assert apply_depends_on(o3.owner, [o1.owner, o2.owner])
 
 
 @pytest.mark.xfail(reason="Not implemented")