RFR: JDK-8224963: Char-Byte Performance Enhancement

Adam Farley8 adam.farley at uk.ibm.com
Wed May 29 09:45:05 UTC 2019

Hi All,

Could someone familiar with the Hotspot JIT please review and opine on the 

The Char-Byte encoding/decoding methods inside some of the sun.nio.cs 
(such as US_ASCII) see a lot of use, and OpenJDK on the OpenJ9 VM seems to
do this a lot faster.

Is it possible to achieve a similar improvement on OpenJDK on Hotspot by
tweaking the CL code to match Hotspot JIT compiler idioms, or by 
a method name for the HS JIT to match on?

An example of these changes to US_ASCII.java is linked below. No OpenJ9 
is included in the work item or the webrev, to avoid contamination.

Work item: https://bugs.openjdk.java.net/browse/JDK-8224963

Example Webrev: http://cr.openjdk.java.net/~afarley/8224963/webrev/ 

Best Regards

Adam Farley 
IBM Runtimes

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