Something needs to happen with shared, and soon.

[deadalnix]

Le 15/11/2012 15:22, Sean Kelly a écrit :
> On Nov 15, 2012, at 3:05 PM, David Nadlinger<see at klickverbot.at>  wrote:
>
>> On Thursday, 15 November 2012 at 22:57:54 UTC, Andrei Alexandrescu wrote:
>>> On 11/15/12 1:29 PM, David Nadlinger wrote:
>>>> On Wednesday, 14 November 2012 at 17:54:16 UTC, Andrei Alexandrescu wrote:
>>>>> That is correct. My point is that compiler implementers would follow
>>>>> some specification. That specification would contain informationt hat
>>>>> atomicLoad and atomicStore must have special properties that put them
>>>>> apart from any other functions.
>>>>
>>>> What are these special properties? Sorry, it seems like we are talking
>>>> past each other…
>>>
>>> For example you can't hoist a memory operation before a shared load or after a shared store.
>>
>> Well, to be picky, that depends on what kind of memory operation you mean – moving non-volatile loads/stores across volatile ones is typically considered acceptable.
>
> Usually not, really.  Like if you implement a mutex, you don't want non-volatile operations to be hoisted above the mutex acquire or sunk below the mutex release.  However, it's safe to move additional operations into the block where the mutex is held.

If it is known that the memory read/write is thread local, this is safe, 
even in the case of a mutex.