testsincos.cc

#include <stdio.h>
#include <chrono>
#include <inttypes.h>
#include <math.h>

using Clock = std::chrono::high_resolution_clock;
using Timepoint = Clock::time_point;

static inline void mysincos(float a, float * __restrict s, float * __restrict c)
{
    __asm__(
        "fsincos\n\t"
        : [c] "+t" (a)
        , [s] "=u" (*s)
    );
    *c = a;
}

int main()
{
    float c, s;
    float p = 3.14159265358979323f;
    size_t iters = 1048576;
    float d = p / (iters * 0.5f);
    float a = 0;
    volatile float v;

    Timepoint st = Clock::now();
    for (size_t i = 0; i < iters; ++i) {
        float a = i * d - p;
        mysincos(a, &s, &c);
        v=s;
        v=c;
    }
    Timepoint en = Clock::now();
    printf("fsincos %" PRIu64 "\n", (uint64_t)std::chrono::duration_cast<
            std::chrono::nanoseconds>(en - st).count() / iters);

    st = Clock::now();
    for (size_t i = 0; i < iters; ++i) {
        float a = i * d - p;
        s = sinf(a);
        c = cosf(a);
        v=s;
        v=c;
    }
    en = Clock::now();
    printf("sin cos %" PRIu64 "\n", (uint64_t)std::chrono::duration_cast<
            std::chrono::nanoseconds>(en - st).count() / iters);
}