RFR: 6869327: Add new C2 flag to keep safepoints in counted loops.

[Vladimir Kozlov]

On 12/1/15 3:10 AM, Andreas Eriksson wrote:
>
>
> On 2015-12-01 01:42, Vladimir Kozlov wrote:
>> Looks good.
>>
>> Did you run it in JPRT?
>
> Yes, a JPRT run with tests from hotspot/test/compiler/loopopts added looks good.

Thanks

> (Except for TestCastIINoLoopLimitCheck.java failing because the fix for JDK-8141706 wasn't in jdk9-hs-comp.)
>
>>
>> Add -XX:+IgnoreUrecognizedVMOptions flags to the list of flags (put it first) in the test because
>> UseCountedLoopSafepoints is only C2 flag and TieredCompilation is Server VM flag.
>
> Alright, will do.
> I'll go ahead and push this later this week (with that change), unless someone objects.

Sounds good.

Thanks,
Vladimir

>
> Thanks,
> Andreas
>
>>
>> Thanks,
>> Vladimir
>>
>> On 11/27/15 5:01 AM, Andreas Eriksson wrote:
>>> Hi,
>>>
>>> Please review this change that adds a flag to keep a safepoint in counted loops.
>>>
>>> Currently C2 removes safepoints in counted loops.
>>> This can force other safepointing threads to wait for the counted loop thread for long periods of time.
>>> This change adds a flag, UseCountedLoopSafepoints, which keeps a safepoint in the loop. Its default value is false.
>>>
>>> Bug: 6869327: Add new C2 flag to keep safepoints in counted loops.
>>> https://bugs.openjdk.java.net/browse/JDK-6869327
>>>
>>> Webrev: http://cr.openjdk.java.net/~aeriksso/6869327/webrev.00/
>>>
>>> Thanks,
>>> Andreas
>