aarch64: C2 fast lock/unlock issues
aph at redhat.com
Wed Sep 2 14:41:02 UTC 2015
On 09/02/2015 03:29 PM, Andrew Haley wrote:
> So any other thread waiting for the counter to hit a value would not
> see it. And we do not see the writes of other threads. This is
> (It's also, IIRC, why I rejected this approach before.)
Mmmm, I posted that message too quickly before fully thinking
about it; sorry.
Any Java program which did something like that would be incorrect
because it would be accessing the field n outside the lock, and so
there would be no happens-before relationship between the threads, and
all bets would be off anyway.
But I'm still not happy with this. At the very least it is rather
odd, and I think that it may be possible to get some surprising
(if not completely illegal) results with it.
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