On Thursday, 15 November 2012 at 23:22:32 UTC, Sean Kelly wrote:
On Nov 15, 2012, at 3:05 PM, David Nadlinger
<[email protected]> wrote:
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.
Oh well, I was just being stupid when typing up my response: What
I meant to say is that you _can_ reorder a set of memory
operations involving atomic/volatile ones unless you violate the
guarantees of the chosen memory order option.
So, for Andrei's statement to be true, shared needs to be defined
as making all memory operations sequentially consistent. Walter
doesn't seem to think this is the way to go, at least if that is
what he is referring to as »memory barriers«.
David
