测试代码：

    static volatile uint32_t cnt;cnt = 0;uint64_t time = time_spent({while (cnt < 1000000){cnt++;}});log_info("test time spent: %llu us\r\n", time);

结果：

//未开启Cache
fmc_ram test:
uint32_t spent time: 955963 us
uint64_t spent time: 1091907 us
float spent time: 247405 us
double spent time: 1092104 us
iram test:
uint32_t spent time: 13462 us
uint64_t spent time: 956284 us
float spent time: 1227114 us
double spent time: 1091992 us//开启Cache
fmc_ram test:
uint32_t spent time: 227392 us
uint64_t spent time: 329214 us
float spent time: 244203 us
double spent time: 353283 us
iram test:
uint32_t spent time: 10476 us
uint64_t spent time: 16780 us
float spent time: 25151 us
double spent time: 37813 us

未开启Cache	SDRAM  (FMC)	32位	955 963 us
		64位	1 091 907 us
		float	247 405 us
		double	1 092 104 us
	IRAM  (AXI)	uint32_t	13 462 us
		uint64_t	956 284 us
		float	1 227 114 us
		double	1 091 992 us
开启Cache	SDRAM  (FMC)	32位	227 392us
		64位	329 214 us
		float	244 203 us
		double	353 283 us
	IRAM  (AXI)	uint32_t	10 476 us
		uint64_t	16 780 us
		float	25 151 us
		double	37 813 us

测试环境：
1. 主频：480MHZ
2. 开启double硬件加速