How to change sanitizer's report function report __asan_report_*

Hello everybody,

I want to add a special checker for our memory pool。Set the first bit of pointer as the special checker flag

for example:
void *p = mempool_get(mp);
Assume p mempool_get return a pointer: $(real_pointer) & 0xa0000000

So, I want to change the __asan_report* function to remove the first bit of pointer

How can i change the _asan_report’s first param from void to void **?