MCR and MRC instruction usage - ios

Question

here i have written code to find number of cycles taken by a function but i am getting error at first MCR instruction can any one suggest me how to solve this problem.This code is written in XCODE and running on ios.
#include <stdio.h>
static inline unsigned int get_cyclecount (void)
{
unsigned int value;
// Read CCNT Register
asm volatile ("MRC p15, 0, %0, c9, c13, 0\t\n": "=r"(value));
return value;
}
static inline void init_perfcounters (int do_reset, int enable_divider)
{
// in general enable all counters (including cycle counter)
int value = 1;
// perform reset:
if (do_reset)
{
value |= 2; // reset all counters to zero.
value |= 4; // reset cycle counter to zero.
}
if (enable_divider)
value |= 8; // enable "by 64" divider for CCNT.
value |= 16;
// program the performance-counter control-register:
asm volatile ("MCR p15, 0, %0, c9, c12, 0\t\n" :: "r"(value));
// enable all counters:
asm volatile ("MCR p15, 0, %0, c9, c12, 1\t\n" :: "r"(0x8000000f));
// clear overflows:
asm volatile ("MCR p15, 0, %0, c9, c12, 3\t\n" :: "r"(0x8000000f));
}
int main () {
float x = 100.0f;
float y = 0.00000f;
float inst,cycl,cycl_inst;
int do_reset=0;
int enable_divider=0;
init_perfcounters (1, 0);
// measure the counting overhead:
unsigned int overhead = get_cyclecount();
overhead = get_cyclecount() - overhead;
unsigned int t = get_cyclecount();
// do some stuff here..
log_10_c_function(x);
t = get_cyclecount() - t;
printf ("Totaly %d cycles (including function call) ", t - overhead);
return 0;
}