RFR: jsr166 jdk9 integration wave 9
aleksey.shipilev at gmail.com
Thu Aug 11 20:08:23 UTC 2016
On 08/11/2016 09:59 PM, Martin Buchholz wrote:
> On Thu, Aug 11, 2016 at 10:40 AM, Aleksey Shipilev
>> Why doesn't AtomicBoolean.getAndSet use VarHandle.getAndSet, which is
>> hopefully intrinsified completely?
> Good question. This optimization originated in a suggestion for jdk8,
> where there are no VarHandles.
> VarHandle.getAndSet does not know there are only two values for the int,
> so it is not obvious which one wins. I can imagine getAndSet being
> compiled to a weak cas loop.
getAndSet/getAndAdd have a nice rationale for x86: they compile to
xchg/xadd, respectively. This is what I meant about "intrinsified
>> Any benchmarks backing up this optimization?
> I measured a reduction in bytecode! Does that count?
I measured x86 instructions count, and you would not believe what it
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