test-fsqrt-fullhard.c

#include <stdint.h>

#define TEST(H1)                                     \
    do {                                                                   \
        uint64_t frt; \
        asm("fsqrt %0, %1\n\tfmadd %0, %1, %0, %1" : "=f"(frt) : "f"(H1));      \
    } while (0)

int main(void)
{
    int i = 0;
    __builtin_mtfsb1(46 - 32); __builtin_mtfsb1(38 - 32); __builtin_mtfsb1(32 - 32);
    for (; i < 100000000; ++i) {
        TEST(0x4010000000000000ULL);
        TEST(0x4000000000000000ULL);
        TEST(0x41c0000000000000ULL);
    }
    __builtin_mffs();

    return 0;
}