TEST_SPMC_RESIZE_ORDER
#define TEST_SPMC_RESIZE_PREFILL ((SPMC_ARR_BASESZ << TEST_SPMC_RESIZE_ORDER) - 1)
#define TEST_SPMC_RESIZE_TAIL (SPMC_ARR_BASESZ << TEST_SPMC_RESIZE_ORDER)
if (spmc->cur->order > TEST_SPMC_RESIZE_ORDER)