On 11/15/12 3:30 PM, David Nadlinger wrote:
On Thursday, 15 November 2012 at 23:22:32 UTC, Sean Kelly wrote:
On Nov 15, 2012, at 3:05 PM, David Nadlinger <s...@klickverbot.at> 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«.
Shared must be sequentially consistent.
Andrei
