RFR: 8348638: Performance regression in Math.tanh [v2]

[Jatin Bhateja]

On Wed, 2 Apr 2025 13:46:47 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

>> Mohamed Issa has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Change tanh intrinsic endpoint comparison value to match reference OpenJDK implementation
>
> src/hotspot/cpu/x86/stubGenerator_x86_64_tanh.cpp line 331:
> 
>> 329:   __ andl(rdx, rcx);
>> 330:   __ andl(rcx, 32767);
>> 331:   __ cmpl(rcx, 16438);
> 
> Did you try using "UCOMISD" to directly compare with constant 22.0

[perf_tanh_delimit.txt](https://github.com/user-attachments/files/19573617/perf_tanh_delimit.txt)

Proposed sequence in micro2 shows better path length,  please give this a try.

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PR Review Comment: https://git.openjdk.org/jdk/pull/23889#discussion_r2025378258