RFR: 8348638: Performance regression in Math.tanh [v7]

[Mohamed Issa]

On Thu, 24 Apr 2025 16:51:06 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

>> Mohamed Issa has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Make regular tanh benchmark inputs constant values
>
> test/micro/org/openjdk/bench/java/lang/MathBench.java line 67:
> 
>> 65:     public double double1 = 1.0d, double2 = 2.0d, double81 = 81.0d, doubleNegative12 = -12.0d, double4Dot1 = 4.1d, double0Dot5 = 0.5d;
>> 66: 
>> 67:     public static final double tanhConstInputs[] = {-2.0, -1.0, -0.5, -0.1, 0.0, 0.1, 0.5, 1.0, 2.0};
> 
> Static final arrays have mutable elements, you should declare individual static fields with different constant values.
> We can also use @Stable annotation, in that case array index must be a constant. Is better to go with few individual static final fields with constant values.

I switched to individual static final fields with constant values. There are separate micro-benchmarks included as well.

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PR Review Comment: https://git.openjdk.org/jdk/pull/23889#discussion_r2059413513