Re: c/8221: return value of a function is forgotten

[Andrew Pinski <pinskia at physics dot uc dot edu>]

The following reply was made to PR c/8221; it has been noted by GNATS.

From: Andrew Pinski <pinskia@physics.uc.edu>
To: c.kaliszyk@zodiac.mimuw.edu.pl
Cc: gcc-gnats@gcc.gnu.org, cek@wp.pl
Subject: Re: c/8221: return value of a function is forgotten
Date: Mon, 14 Oct 2002 02:12:23 -0700

 On Monday, Oct 14, 2002, at 01:44 US/Pacific, 
 c.kaliszyk@zodiac.mimuw.edu.pl wrote:
 > I call "gcc -O2" on this:
 > --cut--
 > inline int getcputime(void) {
 >   int i;
 >   __asm__(
 >     "rdtsc
 >     movl %%eax, %0"
 >     : :"g" (i) :"ax", "dx");
 >   return i;
 > }
 >
 > int main(void) {
 >   int x =3D getcputime();
 >   int y =3D getcputime();
 >   printf ("Time measure resolution: %i\n", y - x);
 >   return 0;
 > }
 
 
 I think you constraints are wrong, this works for me:
 inline int getcputime(void) {
    int i;
    __asm__ volatile(
      "rdtsc\n\
      movl %%eax, %0"
      : "=g" (i) : :"eax", "edx");
    return i;
 }
 
 int main(void) {
    int x = getcputime();
    int y = getcputime();
    printf ("Time measure resolution: %i\n", y - x);
    return 0;
 }
 
 
 read
 http://gcc.gnu.org/onlinedocs/gcc-3.2/gcc/Extended-Asm.html
 for information, this helped me get the correct result.
 
 Thanks,
 Andrew Pinski
 
 PS I think this bug is user error so can someone close it.