[Info-vax] Volatile, was: Re: yet another sys$qiow question

[John Reagan]

On Thursday, August 20, 2015 at 8:59:42 AM UTC-4, Johnny Billquist wrote:

> 
> It's more than a "hint". Volatile tells the compiler that it is never 
> allowed to optimize away any reads or writes the that variable in the 
> code. They all need to be preserved, and the order of reads/writes also 
> needs to be preserved.
> 
> 	Johnny

And for stack-based volatile variables, I believe we extend the variable's lifetime to the entire routine.  For C scope-variables, I'm not sure if that is extended to just the whole scope or if that is promoted to the enclosing routine.