RFR(S) : 8225554 : add JFR event for uncommon trap

[Markus Gronlund]

 Hi Igor,

Thank you for looking into providing this support.

This work partly overlaps with something I have been working on under the following enhancement:

Enh: https://bugs.openjdk.java.net/browse/JDK-8216041

I have had a patch somewhat semi-ready for some years now, please see:
http://cr.openjdk.java.net/~mgronlun/8216041/

Here is what the information set could look visually by default (no structured rendering) in JDK Mission Control:
http://cr.openjdk.java.net/~mgronlun/8216041/DeoptimizationEvent.jpg

Maybe we should merge our work for this effort (I am interested in your test case)?

I think we need to take a larger view on this, especially to see if this information could also be made understandable and maybe even useful to the end-user / developer.

This is the reason I choose to use the "deoptimization" concept instead of the more internal UncomonTrap.

Let's see if we together can craft a useful event here.

Thanks
Markus

-----Original Message-----
From: Igor Ignatyev 
Sent: den 11 juni 2019 20:49
To: hotspot-jfr-dev at openjdk.java.net; hotspot compiler <hotspot-compiler-dev at openjdk.java.net>
Subject: RFR(S) : 8225554 : add JFR event for uncommon trap

http://cr.openjdk.java.net/~iignatyev//8225554/webrev.00/index.html
> 187 lines changed: 184 ins; 0 del; 3 mod;

Hi all,

could you please review this small patch which adds jfr event for uncommon trap?

webrev: http://cr.openjdk.java.net/~iignatyev//8225554/webrev.00/index.html
JBS: https://bugs.openjdk.java.net/browse/JDK-8225554
testing:
 - tier1 (which includes a newly added test)
 - modified version of compiler/intrinsics/klass/CastNullCheckDroppingsTest.java (see JDK-8129092[1])

[1] https://bugs.openjdk.java.net/browse/JDK-8129092

Thanks,
-- Igor