RFR 8229898 [lworld] Enable C1 by default

[Tobias Hartmann]

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?

> + 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?

Thanks,
Tobias