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

[Srinivas Vamsi Parasa]

On Wed, 4 Sep 2024 00:01:09 GMT, Joe Darcy <darcy at openjdk.org> wrote:

> If the test is going to use randomness, then its jtreg tags should include
> 
> `@key randomness`
> 
> and it is preferable to use jdk.test.lib.RandomFactory to get and Random object since that handles printing out a key so the random sequence can be replicated if the test fails.

Please see the test updated to use `@key randomness` and` jdk.test.lib.RandomFactory` to get and Random object.

> The allowable worst-case error is 2.5 ulp, although at many arguments FDLIBM has a smaller error.
> For a general Math vs StrictMath test with an allowable 2.5 ulp error, without knowing how accurate FDLIBM is for that function and argument, a large error of approx. 2X the nominal error should be allowed (in case FDLIBM errors in one direction and the Math method errors in the other direction).
>
So far the tests haven't failed with error of 2.5ulp. Would it be better to make it 5ulp? Please let me know.

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PR Review Comment: https://git.openjdk.org/jdk/pull/20657#discussion_r1746034895