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From "Robert Stupp (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (CASSANDRA-12343) Make 'static final boolean' easier to optimize for Hotspot
Date Sat, 30 Jul 2016 08:10:20 GMT

     [ https://issues.apache.org/jira/browse/CASSANDRA-12343?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Robert Stupp updated CASSANDRA-12343:
-------------------------------------
    Status: Patch Available  (was: Open)

> Make 'static final boolean' easier to optimize for Hotspot
> ----------------------------------------------------------
>
>                 Key: CASSANDRA-12343
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-12343
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Robert Stupp
>            Assignee: Robert Stupp
>            Priority: Trivial
>             Fix For: 3.x
>
>
> Hotspot is able to optimize condition checks on `static final` fields. But the compiler
can only optimize if the referenced "constant" is the first condition to check. (If I understood
the optimization in Hotspot correctly.)
> I.e. the first {{if}} block can be "eliminated" whereas the second cannot:
> {code}
> class Foo {
>   static final boolean CONST = /* some fragment evaluating to false */;
>   
>   public void doSomeStuff(boolean param) {
>     if (!CONST) {
>       // this code block can be eliminated
>     }
>     if (!CONST && param) {
>       // this code block can be eliminated
>     }
>     if (param && !CONST) {
>       // this code block cannot be eliminated due to some compiler logic
>     }
>     
>   }
> }
> {code}
> Linked patch changes the order in some {{if}} statements and migrates a few methods to
static final fields.
> ||trunk|[branch|https://github.com/apache/cassandra/compare/trunk...snazy:boolean-hotspot]|[testall|http://cassci.datastax.com/view/Dev/view/snazy/job/snazy-boolean-hotspot-testall/lastSuccessfulBuild/]|[dtest|http://cassci.datastax.com/view/Dev/view/snazy/job/snazy-boolean-hotspot-dtest/lastSuccessfulBuild/]



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