Function converge_codesizes 

pub(crate) fn converge_codesizes<T, K: PartialEq>(
    initial: K,
    pass: impl FnMut(&K) -> Result<(T, K), CodegenError>,
) -> Result<T, CodegenError>

Runs codegen passes until the values a pass depends on are the ones it produces, starting from initial, and returns the output of the last pass