*
     * <p>
     * Example:
     *
     * <pre>
     * project.sync {
     *    from 'my/shared/dependencyDir'
     *    into 'build/deps/compile'
     * }
     * </pre>
     * Note that you can preserve output that already exists in the destination directory:
     * <pre>
     * project.sync {
     *     from 'source'

This pass is intended to run after the split_into_island_per_op
pass. That pass splits up multi-op islands into multiple individual islands
wrapping a single op without applying any control deps between the new
islands. So, this pass is needed in order to make preservation of the
semantic ordering relationships between ops as determined by side effect
analysis explicit in the IR.

Example: original program: