RFR: 8360559: Optimize Math.sinh for x86 64 bit platforms [v2]
Sandhya Viswanathan
sviswanathan at openjdk.org
Wed Jul 30 23:51:54 UTC 2025
On Thu, 17 Jul 2025 18:46:06 GMT, Mohamed Issa <missa at openjdk.org> wrote:
>> The goal of this PR is to implement an x86_64 intrinsic for java.lang.Math.sinh() 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 command to run all range specific micro-benchmarks is posted below.
>>
>> `make test TEST="micro:SinhPerf.SinhPerfRanges"`
>>
>> The results of all tests posted below were captured with an [Intel® Xeon 8488C](https://advisor.cloudzero.com/aws/ec2/r7i.metal-24xl) using [OpenJDK v26-b4](https://github.com/openjdk/jdk/releases/tag/jdk-26%2B4) 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 an an average uplift of 64% when input values fall into the middle three ranges where heavy computation is required. However, very small inputs and very large inputs show drops of 74% and 66% respectively.
>>
>> | Input range(s) | Baseline throughput (ops/ms) | Intrinsic throughput (ops/ms) | Speedup |
>> | :------------------------------------: | :-------------------------------: | :--------------------------------: | :--------: |
>> | [-2^(-28), 2^(-28)] | 844160 | 216029 | 0.26x |
>> | [-22, -2^(-28)], [2^(-28), 22] | 81662 | 157351 | 1.93x |
>> | [-709.78, -22], [22, 709.78] | 119075 | 167635 | 1.41x |
>> | [-710.48, -709.78], [709.78, 710.48] | 111636 | 177125 | 1.59x |
>> | (-INF, -710.48], [710.48, INF) | 959296 | 313839 | 0.33x |
>>
>> Finally, the `jtreg:test/jdk/java/lang/Math/HyperbolicTests.java` test passed with the changes.
>
> Mohamed Issa has updated the pull request incrementally with one additional commit since the last revision:
>
> Move error bound to separate section in comment header
src/hotspot/cpu/x86/stubGenerator_x86_64_sinh.cpp line 325:
> 323: __ jcc(Assembler::aboveEqual, L_2TAG_PACKET_0_0_2); // Branch only if |x| is not in [23/64, 3*2^8)
> 324: __ movsd(xmm3, ExternalAddress(HALFMASK), r11 /*rscratch*/);
> 325: __ movsd(xmm1, ExternalAddress(L2E), r11 /*rscratch*/);
xmm1 is used at L_2TAG_PACKET_0_0_2 -> L_2TAG_PACKET_3_0_2 line 507 below so should be loaded prior to L_2TAG_PACKET_0_0_2.
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PR Review Comment: https://git.openjdk.org/jdk/pull/26152#discussion_r2243550202
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