RFR: 8345298: RISC-V: Add riscv backend for Float16 operations - scalar [v4]

[Hamlin Li]

On Thu, 6 Mar 2025 14:30:40 GMT, Hamlin Li <mli at openjdk.org> wrote:

>> Hi,
>> Can you help to review this patch?
>> It's an implementation of https://github.com/openjdk/jdk/pull/22754 on riscv.
>> 
>> ## Performance
>> 
>> data
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>> Benchmark | (vectorDim) | Mode | Cnt | Score -master | Error | Score - patch | Error | Units | Improvement (master/patch)
>> -- | -- | -- | -- | -- | -- | -- | -- | -- | --
>> Float16OperationsBenchmark.absBenchmark | 256 | avgt | 10 | 219.564 | 0.076 | 219.597 | 0.081 | ns/op | 1
>> Float16OperationsBenchmark.absBenchmark | 512 | avgt | 10 | 358.873 | 0.575 | 355.011 | 0.07 | ns/op | 1.011
>> Float16OperationsBenchmark.absBenchmark | 1024 | avgt | 10 | 582.361 | 0.189 | 581.832 | 0.006 | ns/op | 1.001
>> Float16OperationsBenchmark.absBenchmark | 2048 | avgt | 10 | 1035.633 | 0.239 | 1034.854 | 0.284 | ns/op | 1.001
>> Float16OperationsBenchmark.addBenchmark | 256 | avgt | 10 | 4951.702 | 0.194 | 2593.835 | 0.066 | ns/op | 1.909
>> Float16OperationsBenchmark.addBenchmark | 512 | avgt | 10 | 9867.909 | 0.314 | 5167.568 | 0.162 | ns/op | 1.91
>> Float16OperationsBenchmark.addBenchmark | 1024 | avgt | 10 | 21324.318 | 1.651 | 10016.456 | 1.07 | ns/op | 2.129
>> Float16OperationsBenchmark.addBenchmark | 2048 | avgt | 10 | 42618.969 | 3.877 | 19985.662 | 1.233 | ns/op | 2.132
>> Float16OperationsBenchmark.cosineSimilarityDequantizedFP16 | 256 | avgt | 10 | 2811.45 | 0.441 | 2701.419 | 140.699 | ns/op | 1.041
>> Float16OperationsBenchmark.cosineSimilarityDequantizedFP16 | 512 | avgt | 10 | 5568.561 | 0.654 | 5577.598 | 1.123 | ns/op | 0.998
>> Float16OperationsBenchmark.cosineSimilarityDequantizedFP16 | 1024 | avgt | 10 | 11109.108 | 1.7 | 11095.644 | 0.644 | ns/op | 1.001
>> Float16OperationsBenchmark.cosineSimilarityDequantizedFP16 | 2048 | avgt | 10 | 20017.095 | 0.778 | 21560.165 | 0.515 | ns/op | 0.928
>> Float16OperationsBenchmark.cosineSimilarityDoubleRoundingFP16 | 256 | avgt | 10 | 20864.303 | 23.768 | 1345.192 | 0.274 | ns/op | 15.51
>> Float16OperationsBenchmark.cosineSimilarityDoubleRoundingFP16 | 512 | avgt | 10 | 43596.262 | 102.075 | 2580.035 | 0.397 | ns/op | 16.898
>> Float16OperationsBenchmark.cosineSimilarityDoubleRoundingFP16 | 1024 | avgt | 10 | 91565.81...
>
> Hamlin Li has updated the pull request incrementally with one additional commit since the last revision:
> 
>   remove TestFloat16VectorConvChain test for riscv temporariely

BTW, I just removed TestFloat16VectorConvChain test for riscv temporariely, as with this patch the ConvF2HF(AddF(ConvHF2F, ConvHF2F)) will be replaced by a ReinterpretHF2S(AddHF(ReinterpretS2HF, ReinterpretS2HF)).

In the short future, when we support vectorization of float16 operations, we can enable the test, but for riscv it will still be different form of Nodes, could be something like VectorReinterpretHF2S(VectorAddHF(VectorReinterpretS2HF, VectorReinterpretS2HF)).

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PR Comment: https://git.openjdk.org/jdk/pull/23844#issuecomment-2704025799