# Copyright (c) Meta Platforms, Inc. and affiliates.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
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"""
Remove useless operators from a sorted_graph.
"""
from collections import deque
from typing import List
from aitemplate.compiler.base import Tensor
[docs]def remove_unused_ops(sorted_graph: List[Tensor]) -> None:
"""Remove ops which are not src operators of tensors in the input sorted_graph."""
src_ops = set()
to_be_visited_ops = deque()
for node in sorted_graph:
src_ops.update(node._attrs["src_ops"])
to_be_visited_ops.extend(node._attrs["dst_ops"])
visited_ops = set()
while len(to_be_visited_ops) > 0:
next_op = to_be_visited_ops.popleft()
if next_op in visited_ops:
continue
visited_ops.add(next_op)
if next_op not in src_ops:
for input_tensor in next_op._attrs["inputs"]:
input_tensor._attrs["dst_ops"].discard(next_op)
for output_tensor in next_op._attrs["outputs"]:
to_be_visited_ops.extend(output_tensor._attrs["dst_ops"])