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from torch import fx
from torch._inductor.pattern_matcher import stable_topological_sort

from ...magi_depyf.timeline import emit_pass_lifecycle
from ..pass_base import MagiInductorPass


class PostCleanupPass(MagiInductorPass):
    """
    This pass performs cleanup after custom passes.
    It topologically sorts the graph and removes unused nodes.
    This is needed because the pattern matcher does not guarantee producing
    a topologically sorted graph, and there may be unused nodes left around.
    """

    @emit_pass_lifecycle
    def __call__(self, graph: fx.Graph) -> None:
        stable_topological_sort(graph)
        graph.eliminate_dead_code()