To help LDC/GDC

[Dicebot]

On Tuesday, 9 April 2013 at 08:31:06 UTC, Manu wrote:
> Errrr, no?
> Only globals are thread-local. Everything else is either stack 
> or heap
> allocated.

Well, stack is also thread-local, isn't it? ;) Heap objection 
accepted.

> Yes but that's ultimately useless. If sharing is undefined, and 
> you can
> only use pass something to another thread via shared, then you 
> basically
> can't use threads.
> shared is facilitated by blind casting. And codegen (which 
> doesn't know if
> something actually WAS shared or not) can't be assuming it 
> wasn't.
> I can't imagine a situation other than immutable where the 
> compiler is able
> to presume __restrict in this way.

My memories may be vague (I have been reading about it in a 
d-concurrency mail list used a looong time ago) but initial 
concept was quite elegant: everything that is intended to be 
shared should me marked with qualifiers. Function shall accepts 
shared parameters, do locks on them (which casts away shared in a 
library) and then use in regular functions. This clearly defines 
the distinction between functions that need to take care of 
synchronization and functions that can just work. I still think 
it is a clever concept, but without proper support in D/Phobos 
implementation is has become a cumbersome restriction.

Once again, that is what my memory says, I'd like to be corrected 
by someone who has actually participated in that mail list.