Re: Fw: [isocpp-parallel] OOTA fix (via fake branch-after-load) discussion

[Boqun Feng]

On Thu, Nov 09, 2023 at 05:25:05PM +0100, Jonas Oberhauser wrote:
[...]
> > 4.	Semantics of volatile.	Perhaps the current state is the best
> > 	that can be hoped for, but given that the current state is a
> > 	few vague words in the standard in combination with the fact
> > 	that C-language device drivers must be able to use volatile
> > 	to reliably and concurrently access memory shared with device
> > 	firmware, one would hope for better.
> 
> 
> Is it really so bad? I think the definition in the manual is quite precise,
> if confusing. (volatiles are visible side effects and must therefore have
> the same program order in the abstract machine and in the implementation,
> and that's pretty much it).
> 

But I don't think there is any mention on whether current volatile
accesses can be excluded from data race, or whether a volatile access
on a machine-word size natually aligned object can be teared or not.

Regards,
Boqun

> There should just be a large explanatory note about what it implies and what
> it doesn't imply.
> 
>