Function replace_subexpr_and_reduce 

fn replace_subexpr_and_reduce(
    predicate: &mut MirScalarExpr,
    replace_if_equal_to: &MirScalarExpr,
    replace_with: &MirScalarExpr,
    repr_column_types: &[ReprColumnType],
) -> bool

Replace any matching subexpressions in predicate, and if predicate has changed, reduce it. Return whether predicate has changed.