[CASSANDRA-12343] Make 'static final boolean' easier to optimize for Hotspot

• Type: Improvement
• Status: Resolved
• Priority: Low
• Resolution: Fixed
• Fix Version/s: 3.10
• Assignee: Robert Stupp
• Reporter: Robert Stupp

Authors

Robert Stupp

Reviewers

Branimir Lambov

• Created: 29/Jul/16 16:02
• Updated: 16/Apr/19 09:30
• Resolved: 04/Aug/16 13:16

Description

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:

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
    }
    
  }
}

Linked patch changes the order in some if statements and migrates a few methods to static final fields.

trunk	branch	testall	dtest