From: Alexander Terekhov (terekhov_at_[hidden])
Date: 2004-10-01 07:34:52
Peter Dimov wrote:
>
> Alexander Terekhov wrote:
> > Peter Dimov wrote:
> >>> C'mon, volatile is brain-dead.
> >>
> >> Nobody's arguing otherwise. ;-) But a nop it isn't.
> >
> > Nop works just fine for your volatile accesses. You can't prove non-
> > conformance without trying to fool the program using debugger (or
> > things like that... beyond the scope of the standard).
>
> Argh. The standard says that the compiler MUST ASSUME that volatile variable
> accesses ARE OBSERVABLE by things OUTSIDE OF THE SCOPE of the standard!
Fine. And the ruler of the outside world (implementation) says:
"observe nop and be happy" (or something like that).
[...]
> Look at it this way:
>
> Nop works just fine for your printf statements. You can't prove
> non-conformance without trying to look at a screen (or things like that...
> beyond the scope of the standard).
Right. And any implementation capable to detect that the output
"goes to dev/null" is free to JIT-optimize it to nops. Good for
global environment (less climate change, etc.), you know.
regards,
alexander.