> diff --git a/delta-islands.c b/delta-islands.c
> new file mode 100644
> index 0000000000..448ddcbbe4
> --- /dev/null
> +++ b/delta-islands.c
> +static void deduplicate_islands(void)
> +{
> + struct remote_island *island, *core = NULL, **list;
> + unsigned int island_count, dst, src, ref, i = 0;
> +
> + island_count = kh_size(remote_islands);
> + list = xmalloc(island_count * sizeof(struct remote_island *));
Please use ALLOC_ARRAY here.
> +
> + kh_foreach_value(remote_islands, island, {
> + list[i++] = island;
> + });
> +
> + for (ref = 0; ref + 1 < island_count; ref++) {
> + for (src = ref + 1, dst = src; src < island_count; src++) {
> + if (list[ref]->hash == list[src]->hash)
> + continue;
> +
> + if (src != dst)
> + list[dst] = list[src];
> +
> + dst++;
> + }
> + island_count = dst;
> + }
> +
> + island_bitmap_size = (island_count / 32) + 1;
> + core = get_core_island();
> +
> + for (i = 0; i < island_count; ++i) {
> + mark_remote_island_1(list[i], core && list[i]->hash == core->hash);
> + }
> +
> + free(list);
> +}
