[aarch64-port-dev ] RFR: [8u] JDK-8211320: AArch64: unsafe.compareAndSetByte() and unsafe.compareAndSetShort() c2 intrinsics broken with negative expected value

[Aleksey Shipilev]

On 8/27/19 6:18 PM, Andrew Dinn wrote:
> I was asked to look at backporting this patch to jdk8u-shenandoah.
> However, I don't believe a backport is appropriate.
> 
> The patch updates ad file encodings and associated assembler cmpxchg
> method code for rules that match CompareAndExchangeB/S and
> CompareAndSwapB/S. Those cases do not apply to jdk8u where there are no
> CompareAndExchange rules and CompareAndSwap rules are only defined for
> I/L/N/P. I'm bery happy to be corrected if I am missing something.

The patch does not indeed look as important for 8u-aarch64. We are sure it does not affect I/L/N/P
shapes, right?

On the other hand, having a generic MacroAssembler::compare_eq and the new test might be beneficial.
If we to adapt that to 8u-aarch64, would we have to mangle out a lot of test code, rendering the
whole thing futile?

I am leaning towards dropping this from 8u-aarch64 backports.

-- 
Thanks,
-Aleksey