Code that used to compile

[Tim Prince]

Does it work better without the clobbers?  I was just revising similar code, where I use the widely used form

   unsigned long long a;
   asm volatile("rdtsc":"=A" (a));
   return a;

along with equivalent code pinched from other sources for other compilers.  True, the error message is inappropriate in the sense
that it doesn't explain the problem.

----- Original Message -----
From: <Laurent.Kersten@alcatel.be>
To: <bug-gcc@gnu.org>
Sent: Tuesday, November 14, 2000 3:03 AM
Subject: Code that used to compile


>
>
> 1
> Dear sirs,
>
> I wrote a small C function that read the TSC counter of my Pentium processor. And this function worked well until a do a compiler
upgrade. The new compiler refuses to compile my code and give me a error message which, I think,  is inappropriate.
>
> Output of gcc -v with the new compiler:
>
> Reading specs from /usr/lib/gcc-lib/i486-suse-linux/2.95.2/specs
> gcc version 2.95.2 19991024 (release)
>
> Error message from  the new compiler (gcc -c rdtsc.c)
>
> rdtsc.c: In function `user_rdtsc':
> rdtsc.c:13: Invalid `asm' statement:
> rdtsc.c:13: fixed or forbidden register 0 (ax) was spilled for class AREG.
>
> Source Code :
>
> unsigned long long
> user_rdtsc (void)
> {
>   union
>   {
>     unsigned long long time;
>     unsigned long time_lh[2];
>   }
>   tsc;
>   __asm__ __volatile__ ("rdtsc"
>                :"=a" (tsc.time_lh[0]), "=d" (tsc.time_lh[1])
>                :
>                :"ax", "dx");
>   return tsc.time;
> }
>
>