size_t new_len = runtime->data_len + padding + len;
size_t new_alloc_len = new_len;
size_t old_alloc_len = runtime->data_alloc_len;
size_t new_len = runtime->data_len + padding + len;
size_t new_alloc_len = new_len;
size_t old_alloc_len = runtime->data_alloc_len;