[Info-vax] yet another sys$qiow question

[Bob Koehler]

In article <mr33s2$2uq$1 at dont-email.me>, David Froble <davef at tsoft-inc.com> writes:
> Johnny Billquist wrote:
> 
> Some of this has caught my attention.
> 
> 
>> Exmaple:
>>   x = iosb;
>>   y = iosb;
> 
> 
>> The C compiler can easily compact this into just one read of the iosb 
>> variable, even if your source code have two reads. And if the system 
>> actaully changed the value between these two reads, then you could argue 
>> that y got the wrong value.
> 
> If this is what you get from optimization, then I got to ask, is optimized code 
> accurate?

   Yes, if the rules of the language define the outcome of the
   statements to be the same as what the optimizer generated.
   In this case it certainly could be.