FULL PRODUCT VERSION :
Java HotSpot(TM) Server VM (build 1.5.0-b64, mixed mode)
Java HotSpot(TM) Server VM (build 1.6.0-ea-b14, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows XP [Version 5.1.2600]

A DESCRIPTION OF THE PROBLEM :
Performance regression in a simple loop evaluating a double expression.

ACTUAL -
Jre 1.4.1 -server : Testing 1.0E8 inlined double moltiplications : 1.496 s.
Jre 5.0 -server : Testing 1.0E8 inlined double moltiplications : 10.722 s.
Jre 6.0 -server : Testing 1.0E8 inlined double moltiplications : 10.737 s.

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.io.*;


public class Speed
{
    static class Evaluator
    {
       public final double eval(double i)
        { return (i * 0.123456) / (i + 1.0); }
    }
    
    static double r;

    public static void main(String[] args)
    {
        Speed sp = new Speed(args);
    }

    public Speed(String[] args)
    {
        run();
    }

    static void printTime(String mes, long time, double v)
    {
        System.out.print(" Testing " + mes + " : ");
        System.out.println( (time / 1000.0) + " s.");
        if (v > 0.0)
            System.out.println(" result = " + v);
        System.out.println();
    }

    public void run()
    {
// Test # 2
testDoubleOpsViaFunctionCall((int) 1E8);
// Test # 3
testInlinedDoubleOps((int) 1E8);
            
    }


    // double operation with function call
    long testDoubleOpsViaFunctionCall(int n)
    {
        double r = 0.0;
        Evaluator evaluator = new Evaluator();
        long start = System.currentTimeMillis();
        for (int i = 1; i <= n; i++)
            r += evaluator.eval((double) i);
        long time = System.currentTimeMillis() - start ;
        printTime(Double.toString((double) n) + " double moltiplications via function call", time, r);
        return time ;
    }

    // Test # 3 -B
    long testInlinedDoubleOps(int n)
    {
        int i;
        double r = 0.0;

        long start = System.currentTimeMillis();
        for (i = 1; i < n; i++)
            r += (i * 0.123456) / (i + 1.0);
        long time = System.currentTimeMillis() - start;
        printTime(Double.toString((double) n) + " inlined double moltiplications", time, r);
        return time ;
    }

}

---------- END SOURCE ----------

Release Regression From : 1.4.2
The above release value was the last known release where this
bug was known to work. Since then there has been a regression.
###@###.### 2004-12-22 01:12:16 GMT