Re: [patch 4/21] fix ARCH_HAS_PREFETCH

[Willy Tarreau]

On Wed, Aug 14, 2002 at 01:58:41PM -0700, H. Peter Anvin wrote:
> Willy Tarreau wrote:
> > This way, some loops could be optimized, and the developpers could explicitely
> > tell the compiler when they need to prevent any optimization.
> > 
> 
> #define __nop() asm volatile("")

and if you want to pass arguments, to guarantee that no optimization will
be done, even on loop constants ?
eg:
  for (i = 0; i < N; i++) {
    j++;
    __nop();
  }

-> might be optimized this way :
  j = N;
  for (i = 0; i < N; i++) {
    __nop();
  }

Perhaps using a volatile for j ?

Cheers,
Willy