RFR: 8313875: Make fields final in java.util.Math: twoToTheDoubleScaleUp, twoToTheDoubleScaleDown

[Andrey Turbanov]

On Mon, 7 Aug 2023 16:43:49 GMT, Raffaello Giulietti <rgiulietti at openjdk.org> wrote:

>> Couple of static fields in Math could be declared `final`.
>
> src/java.base/share/classes/java/lang/Math.java line 3425:
> 
>> 3423:     // Constants used in scalb
>> 3424:     private static final double twoToTheDoubleScaleUp = powerOfTwoD(512);
>> 3425:     private static final double twoToTheDoubleScaleDown = powerOfTwoD(-512);
> 
> Aren't these the _literals_ `0x1p512` and `0x1p-512`, respectively?

Whoa. You are right.

    public static void main(String[] args) {
        System.out.println(twoToTheDoubleScaleUp);
        System.out.println(twoToTheDoubleScaleDown);
        System.out.println(0x1p512);
        System.out.println(0x1p-512);

        System.out.println(twoToTheDoubleScaleUp == 0x1p512);
        System.out.println(twoToTheDoubleScaleDown == 0x1p-512);
    }



1.3407807929942597E154
7.458340731200207E-155
1.3407807929942597E154
7.458340731200207E-155
true
true

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/14875#discussion_r1286196598