[dmd-concurrency] draft 7

[Fawzi Mohamed]

On 2-feb-10, at 07:19, Robert Jacques wrote:

> On Tue, 02 Feb 2010 01:04:37 -0500, Sean Kelly  
> <sean at invisibleduck.org> wrote:
>>> A problem that can come up is that the variable is promoted to a  
>>> register in a loop and is not updated from the memory.
>>> To avoid this one can use volatile. This issue is a priory  
>>> disconnected with the presence of barriers (well one would hope  
>>> that a correct compiler disables "upgrading to registers" for  
>>> variables in a locked section crossing the boundary of it, but a  
>>> priory it doesn't have to be like that, and especially using just  
>>> memory barriers, I would not trust current compilers to always do  
>>> the correct thing without a "volatile".
>>
>> Sadly, volatile is deprecated in D 2.0.  You pretty much have to  
>> use inline asm and rely on the fact that Walter has said D  
>> compilers should never optimize in or across asm code.
>
> Well, to the best of my knowledge volatile has never been  
> implemented in D 1.0, which is one of the reason's it was dropped  
> from D 2.0.

that is very sad, I did find volatile very useful, I was interpreting  
it as something like a way to switch off the optimizations in a code  
segment, so that one can have some kind of portable asm.
I find it very useful together with barriers...