cmake/TestInlineASM_gcc_x86.cpp

   1 int
   2 main()
   3 {
   4   unsigned int _eax,_ebx,_ecx,_edx;
   5   unsigned int level = 0;
   6
   7   /* Test gcc inline asm for x86. Note that we CANNOT plainly use __x86_64__
   8    * to correspond to a 64-bit environment without also checking that __ILP32__
   9    * is NOT set, since x32 uses __x86_64__.
  10    */
  11 #if (defined(__x86_64__) && !defined(__ILP32__))
  12     __asm__("push %%rbx       \n\t"
  13             "cpuid            \n\t"
  14             "movl %%ebx, %1   \n\t"
  15             "pop %%rbx        \n\t"
  16             : "=a"(_eax), "=r"(_ebx), "=c"(_ecx), "=d"(_edx) : "0"(level));
  17 #elif (defined(__x86_64__) && defined(__ILP32__)) || defined(__i386__)
  18     __asm__("push %%ebx       \n\t"
  19             "cpuid            \n\t"
  20             "movl %%ebx, %1   \n\t"
  21             "pop %%ebx        \n\t"
  22             : "=a"(_eax), "=r"(_ebx), "=c"(_ecx), "=d"(_edx) : "0"(level));
  23 #else
  24 #    error Cannot detect whether this is a 32-bit or 64-bit x86 build.
  25 #endif
  26
  27   return 0;
  28 }