Subj : Re: Memory visibility and MS Interlocked instructions
To   : comp.programming.threads
From : Alexander Terekhov
Date : Sat Aug 27 2005 07:23 pm


Joe Seigh wrote:
> 
> Joe Seigh wrote:
> > * The one exception I'm aware of (because I use it myself) is atomic
> > load depends and we can get away with that because so much of lock-free
> > depends on pointer swizzling.
> >
> 
> Speaking of that, what do most people think are its semantics?  A qualified
> acquire (#LoadLoad+#LoadStore) or just a qualified #LoadLoad?

Unidirectional ddacq (ddhlb+ddhsb). The problem is that compiler may be
inclined to turn your data dependency into control condition for which 
you'd need ccacq (cchlb+cchsb), not ddacq. Note also that while cchsb 
is implied on on all existing hardware, cchlb is not.

regards,
alexander.

.