On Tue, 6 May 2025 21:45:34 GMT, Mohamed Issa <d...@openjdk.org> wrote:

>> The goal of this PR is to implement an x86_64 intrinsic for 
>> java.lang.Math.cbrt() using libm. There is a new set of micro-benchmarks are 
>> included to check the performance of specific input value ranges to help 
>> prevent regressions in the future.
>> 
>> The results of all tests posted below were captured with an [IntelĀ® Xeon 
>> 6761P](https://www.intel.com/content/www/us/en/products/sku/241842/intel-xeon-6761p-processor-336m-cache-2-50-ghz/specifications.html)
>>  using [OpenJDK 
>> v25-b21](https://github.com/openjdk/jdk/releases/tag/jdk-25%2B21) as the 
>> baseline version.
>> 
>> For performance data collected with the new built in range micro-benchmark, 
>> see the table below. Each result is the mean of 8 individual runs, and the 
>> input ranges used match those from the original Java implementation. 
>> Overall, the intrinsic provides a major uplift of 169% when very small 
>> inputs are used and a more modest uplift of 45% for all other inputs.
>> 
>> | Input range(s)                                  | Throughput with baseline 
>> (op/s) | Throughput with intrinsic (op/s) | Speedup |
>> | :-------------------------------------: | 
>> :----------------------------------: | :----------------------------------: 
>> | :---------: |
>> | [-2^(-1022), 2^(-1022)]                   | 6568                           
>>                   | 17678                                          | 2.69x   
>>     |
>> | (-INF, -2^(-1022)], [2^(-1022), INF) | 138932                              
>>            | 200897                                        | 1.45x       |
>> 
>> Finally, the `jtreg:test/jdk/java/lang/Math/CubeRootTests.java` test passed 
>> with the changes.
>
> Mohamed Issa has updated the pull request incrementally with one additional 
> commit since the last revision:
> 
>   Add new set of cbrt micro-benchmarks

This PR looks good to me. I independently ran the correctness tests and 
performance benchmarks. 

Thanks,
Vamsi

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

Marked as reviewed by sparasa (Author).

PR Review: https://git.openjdk.org/jdk/pull/24470#pullrequestreview-2872425795

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