RFR(M): 8080289: Intermediate writes in a loop not eliminated by optimizer

[Roland Westrelin]

> So what does the graph look like for this example?

I haven’t checked but I would expect:

...->MB->->ST(y=2)->MB->ST(x=1)->MB->ST(y=1)->...

if support_IRIW_for_not_multiple_copy_atomic_cpu is false

...->ST(y=2)->ST(y=1)->...
...->ST(x=1)->...

otherwise

Roland.

> 
> sent from my phone
> 
> On Jun 23, 2015 6:50 AM, "Roland Westrelin" <roland.westrelin at oracle.com> wrote:
> 
> >> What about
> >>
> >> volatile int y;
> >> volatile int x;
> >>
> >> y=1
> >> x=1
> >> y=2
> >>
> >> transformed to:
> >>
> >> x=1
> >> y=2
> >>
> >> ?
> >
> > I think this is not allowed, since operations over "x" get tied up in
> > the synchronization order.
> 
> Thanks. Then for support_IRIW_for_not_multiple_copy_atomic_cpu true, I don’t see how incorrect reordering is prevented.
> 
> Roland.