RFR: 8338694: x86_64 intrinsic for tanh using libm [v2]

[Srinivas Vamsi Parasa]

On Tue, 3 Sep 2024 22:55:18 GMT, Joe Darcy <darcy at openjdk.org> wrote:

>> Srinivas Vamsi Parasa has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Add stub initialization and extra tanh tests
>
> test/jdk/java/lang/Math/HyperbolicTests.java line 984:
> 
>> 982:         double b1 = 0.02;
>> 983:         double b2 = 5.1;
>> 984:         double b3 = 55 * Math.log(2)/2; // ~19.062
> 
> Probably better to use StrictMath.log here or, better use, precompute the value as a constant and document its conceptual origin.

Please see the updated code which uses the precomputed value of `b3`.

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PR Review Comment: https://git.openjdk.org/jdk/pull/20657#discussion_r1746031432