Inline asm opcode

inline_opcode.c

/* http://habrahabr.ru/company/intel/blog/200658/
   gcc -O0 -Wall mulsd.c
   ./a.out
   4.000000 2.000000
*/

#include <stdio.h>

int main() {
    double a[2] = {2, 2}, b[2] = {0, 0};
    __asm__ __volatile__ (
         // Copy data from a to xmm7 register
         "movupd %1, %%xmm7\n"

         // Opcode: "mulsd %%xmm7, %%xmm7\n"
         ".byte 0xf2, 0x66, 0x0f, 0x59, 0xff\n"

         // Copy data from xmm7 register to b
         "movupd %%xmm7, %0\n"
         :"=m"(*b)
         :"m"(*a)
         :
    ); 
    printf("%lf %lf\n", b[0], b[1]);
    return 0;
}