ir_lowering_match.py 文件源码

def _flatten_location_translations(location_translations):
    """If location A translates to B, and B to C, then make A translate directly to C.

    Args:
        location_translations: dict of Location -> Location, where the key translates to the value.
                               Mutated in place for efficiency and simplicity of implementation.
    """
    sources_to_process = set(six.iterkeys(location_translations))

    def _update_translation(source):
        """Return the proper (fully-flattened) translation for the given location."""
        destination = location_translations[source]
        if destination not in location_translations:
            # "destination" cannot be translated, no further flattening required.
            return destination
        else:
            # "destination" can itself be translated -- do so,
            # and then flatten "source" to the final translation as well.
            sources_to_process.discard(destination)
            final_destination = _update_translation(destination)
            location_translations[source] = final_destination
            return final_destination

    while sources_to_process:
        _update_translation(sources_to_process.pop())