RFR (XS) 8156068: Unsafe.{get|set}Opaque should be single copy atomic

[Vladimir Ivanov]

Looks good.

Best regards,
Vladimir Ivanov

On 5/5/16 10:06 PM, Aleksey Shipilev wrote:
> Hi,
>
> Please review a tiny fix in C2 intrinsics that make
> Unsafe.{get|set}Opaque single-copy atomic, as intended. These opaque
> methods are supposed to act like std::atomic(..., memord_relaxed), that
> is, do not induce ordering, but still provide access atomicity.
>
> Interpreter and C1 are delegating to volatile get/set, and so are atomic
> already. C2 has a little bug that was introduced along with the initial
> VarHandles change.
>
> Bug:
>   https://bugs.openjdk.java.net/browse/JDK-8156068
>
> Webrev:
>   http://cr.openjdk.java.net/~shade/8156068/webrev.00/
>
> Testing: jcstress atomicity test on 32-bit x86; RBT (hs-tier0-comp).
>
> Thanks,
> -Aleksey
>
>