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#include <stdio.h>
#include <string.h>
double emit_fmadd(double a, double b, double c) __attribute ((noinline));
double emit_fmadd(double a, double b, double c)
{
return a*b+c;
}
int main(void)
{
double a = 10.0000;
double b = 1.00001;
double c = 1.001;
double res = emit_fmadd(a,b,c);
unsigned char arr[sizeof(res)];
memcpy(arr, &res, sizeof(res));
for (int i = 0; i < sizeof(res); i++)
{
printf("%.2x ", arr[i]);
}
printf("\n");
}
/*
gcc -O3 -march=skylake
emit_fmadd:
vfmadd132sd xmm0, xmm2, xmm1
ret
gcc -O3 -march=x86-64
emit_fmadd:
mulsd xmm0, xmm1
addsd xmm0, xmm2
ret
*/
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Какой багор)))
https://en.wikipedia.org/wiki/Strictfp
но флоаты не нужны
https://en.wikipedia.org/wiki/Multiply%E2%80%93accumulate_operation#Fu sed_multiply%E2%80%93add