error in per-op mode

backends/xnnpack/partition/xnnpack_partitioner.py

@@ -85,20 +85,30 @@ def generate_per_op_partitions(self, ep: ExportedProgram) -> List[Partition]:
         partitions = []
         matched_nodes = self.get_matched_nodes_from_configs(ep)
         partition_id = itertools.count()
-        nodes_seen = set()
+        nodes_seen = {}
         for match in matched_nodes:
-            match_set = set(match)
+            # for debug information we map the node to the string form
+            # of the partition it belongs to
+            match_map = dict.fromkeys(match, str(match))
             # We only create partitions from the first PartitionerConfig match
             # if a subsequent partitioner match contains the same node, we do
             # not create a partition for it
-            if match_set.isdisjoint(nodes_seen):
+            overlap = match_map.keys() & nodes_seen.keys()
+            if len(overlap) == 0:
                 partitions.append(
                     Partition(
                         id=next(partition_id),
-                        nodes=match_set,
+                        nodes=match_map.keys(),
                     )
                 )
-                nodes_seen.update(match_set)
+                nodes_seen.update(match_map)
+            else:
+                error_str = f"per_op mode expects no overlaps between partitions but the partition {match_map.keys()} overlaps with the following partitions:\n"
+                for overlap_node in overlap:
+                    error_str += f"{nodes_seen[overlap_node]}\n"
+
+                raise RuntimeError(error_str)
+
         return partitions