From: Peter Dimov (pdimov_at_[hidden])
Date: 2004-10-01 07:58:31
Alexander Terekhov wrote:
> 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).
OK.
>> 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.
Why should the implementation bother to detect that? Observe nop and be
happy.