RFR 8229898 [lworld] Enable C1 by default

Ioi Lam ioi.lam at oracle.com
Thu Sep 12 16:55:26 UTC 2019

Hi Tobias,

Thanks for the review!

On 9/11/19 12:14 AM, Tobias Hartmann wrote:
> Hi Ioi,
> On 10.09.19 17:50, Ioi Lam wrote:
>> https://bugs.openjdk.java.net/browse/JDK-8229898
>> http://cr.openjdk.java.net/~iklam/valhalla/8229898-enable-c1-default.v01/
>> We have been testing with -XX:+EnableValhallaC1 in mach5 for a couple of weeks and don't see any
>> failures. So this patch is to enable C1 by default (same as the usual JDK)
> Due to your excellent work we achieved a great milestone here. Thank you!
>> (I'll push after a new LW2 update release is done).
> Maybe we should just include it in that update?

I've just pushed it.
>> + By default both C1 and C2 are enabled, and tiered compilation is enabled
>> + The EnableValhallaC1 flag is removed
>>    + To use C1 only: -XX:TieredStopAtLevel=1 -XX:+TieredCompilation
>>    + To use C2 only: -XX:TieredStopAtLevel=4 -XX:-TieredCompilation
>> I adjusted the test cases that are specific to C1/C2 testing to use the flags the new way.
>> I also fixed a bug in ValueTypeTest::parseOutput to properly parse the -XX:+PrintCompilation output
>> (with tiered compilation, an extra number is printed to indicate the tier level). Previously, (due
>> to this parsing bug) we disabled VERIFY_IR when C1 is enabled.
> This looks good to me.
>> @Tobias -- I had to add this. I think when C1 is enabled, the number of counted loops could be
>> different
>>   541       if (TieredCompilation) {
>>   542           // FIXME: TestLWorld.test88 fails with "expected 4 to equal 2"
>>   543           continue;
>>   544       }
> Okay, could you please file a bug?

I filed https://bugs.openjdk.java.net/browse/JDK-8230925

- Ioi
> Thanks,
> Tobias

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