[cpp-threads] Implicit Synchronization

[Lawrence Crowl]

On 7/11/06, Boehm, Hans <hans.boehm at hp.com> wrote:
> We currently propose to have assignment translate to a store<release>
> and conversion to the base type to translate to a load<acquire>.  Thus
> double-checked locking should just work so long as the flag or pointer
> is atomic.

This statement is inconsistent with what I thought was going on.
I thought the semantics of store release were for the one variable,
not all variables.  Am I wrong?

That is, given an atomic boolean guarding an integer,

global data:    int x = 3; atomic<bool> b = false;
thread one:     x = 4;  b = true /* store release */;
thread two:     while ( ! b /* load acquire */ ); int y = x;

is it that y must be four?

Similar questions apply to variables guarded by full-up locks.

-- 
Lawrence Crowl