RFR: 8314124: RISC-V: implement Base64 intrinsic - decoding [v3]

[Hamlin Li]

On Thu, 22 Aug 2024 07:45:58 GMT, Fei Yang <fyang at openjdk.org> wrote:

> Hi, was this ever tested on boards from other vendors like BPI-F3? Seems the JMH data is not there. I can take a look tomorrow. Thanks.

Yes, on bananapi for normal cases it's much better when size getting bigger, I think the reason is it has wider vreg length, which is reasonable. e.g. for size 20000, on K230 the improvement is about 3.082 times, on bananpi it's about 3.856 times.
Please check the data below:
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Benchmark. - bananapi (vlenb == 32) | (addSpecial) | (errorIndex) | (maxNumBytes) | Mode | Cnt | Score +intrinsic | Score -intrinsic | Error | Units | Improvement
-- | -- | -- | -- | -- | -- | -- | -- | -- | -- | --
Base64Decode.testBase64Decode | 0 | 144 | 1 | avgt | 10 | 127.479 | 128.436 | 0.35 | ns/op | 1.008
Base64Decode.testBase64Decode | 0 | 144 | 3 | avgt | 10 | 153.771 | 149.556 | 0.734 | ns/op | 0.973
Base64Decode.testBase64Decode | 0 | 144 | 7 | avgt | 10 | 205.214 | 220.49 | 3.627 | ns/op | 1.074
Base64Decode.testBase64Decode | 0 | 144 | 32 | avgt | 10 | 312.845 | 352.138 | 4.029 | ns/op | 1.126
Base64Decode.testBase64Decode | 0 | 144 | 64 | avgt | 10 | 432.29 | 522.126 | 1.681 | ns/op | 1.208
Base64Decode.testBase64Decode | 0 | 144 | 80 | avgt | 10 | 528.625 | 651.837 | 1.605 | ns/op | 1.233
Base64Decode.testBase64Decode | 0 | 144 | 96 | avgt | 10 | 358.15 | 781.689 | 1.535 | ns/op | 2.183
Base64Decode.testBase64Decode | 0 | 144 | 112 | avgt | 10 | 504.604 | 941.241 | 2.038 | ns/op | 1.865
Base64Decode.testBase64Decode | 0 | 144 | 512 | avgt | 10 | 1949.818 | 4085.463 | 1.364 | ns/op | 2.095
Base64Decode.testBase64Decode | 0 | 144 | 1000 | avgt | 10 | 2551.405 | 6719.044 | 21.669 | ns/op | 2.633
Base64Decode.testBase64Decode | 0 | 144 | 20000 | avgt | 10 | 29470 | 113639.583 | 4.189 | ns/op | 3.856
Base64Decode.testBase64Decode | 0 | 144 | 50000 | avgt | 10 | 70658.042 | 282494.033 | 12.559 | ns/op | 3.998

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PR Comment: https://git.openjdk.org/jdk/pull/20026#issuecomment-2304042266