[Info-vax] yet another sys$qiow question

[Simon Clubley]

On 2015-08-19, Stephen Hoffman <seaohveh at hoffmanlabs.invalid> wrote:
> On 2015-08-19 02:46:48 +0000, John Reagan said:
>
>> You don't need memory barriers.  You do need volatile.  The IOSB is 
>> written behind your back.  volatile says we have to re-fetch.
>
> If that's the case, then there's a shedload of broken C code around 
> (including all of the SYS$EXAMPLES: IOSB references I can find; all of 
> those are not declared volatile, no volatile use in tcpip$examples:, 
> etc), and the OpenVMS and the C documentation and the OpenVMS and C 
> source code examples need updates (e.g. 
><http://h71000.www7.hp.com/commercial/c/docs/5492profile_016.html>), 
> and a release note in the C compiler to flag all this stuff.
>

If what John is saying is correct (and it sounds correct to me based on
what I come across with embedded systems) and if LLVM is as aggressive
as gcc is here, then that's a very distinct possibility unless the LLVM
behaviour is altered to match DEC C's apparent behaviour.

Simon.

-- 
Simon Clubley, clubley at remove_me.eisner.decus.org-Earth.UFP
Microsoft: Bringing you 1980s technology to a 21st century world