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

Roland Westrelin roland.westrelin at oracle.com
Tue Jun 23 16:29:54 UTC 2015

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 supportIRIWfornotmultiplecopyatomiccpu true, I don’t see how incorrect reordering is prevented. Roland.

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