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Date: Wed, 14 Aug 2002 23:11:40 +0200
From: Willy Tarreau <willy@w.ods.org>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Willy Tarreau <willy@w.ods.org>, Rogier Wolff <R.E.Wolff@BitWizard.nl>,
       linux-kernel@vger.kernel.org
Subject: Re: [patch 4/21] fix ARCH_HAS_PREFETCH
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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
 
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