RFR: 8316592: RISC-V: implement poly1305 intrinsic [v7]

[Hamlin Li]

On Thu, 2 Nov 2023 18:29:25 GMT, null <duke at openjdk.org> wrote:

>> Hi everyone, please review this port of [AArch64](https://github.com/openjdk/jdk/blob/master/src/hotspot/cpu/aarch64/stubGenerator_aarch64.cpp#L7124) `_poly1305_processBlocks` intrinsic to RISC-V platform. 
>> 
>> ### Correctness checks
>> 
>> Tier 1 tests are passed. Also I explicitly ran the `test/jdk/com/sun/crypto/provider/Cipher/ChaCha20/unittest/Poly1305UnitTestDriver.java` test for multiple times and it passes.
>> 
>> ### Performance results on T-Head board
>> 
>> #### Results for enabled intrinsic:
>> 
>> Benchmark | (dataSize) | Mode | Cnt | Score | Error | Units
>> -- | -- | -- | -- | -- | -- | --
>> Poly1305DigestBench.digestBuffer | 64| thrpt | 3 | 247207.525 | 2853.920 | ops/s
>> Poly1305DigestBench.digestBuffer | 256 | thrpt | 3 | 221994.065 | 6891.601 | ops/s
>> Poly1305DigestBench.digestBuffer | 1024 | thrpt | 3 | 164485.375 | 4979.286 | ops/s
>> Poly1305DigestBench.digestBuffer | 16384 | thrpt | 3 | 27261.181 | 448.178 | ops/s
>> Poly1305DigestBench.digestBuffer | 1048576 | thrpt | 3 | 270.784 | 3445.077 | ops/s
>> Poly1305DigestBench.digestBytes | 64 | thrpt | 3 | 266049.018 | 9909.155 | ops/s
>> Poly1305DigestBench.digestBytes | 256 | thrpt | 3 | 231891.890 | 715.000 | ops/s
>> Poly1305DigestBench.digestBytes | 1024 | thrpt | 3 | 172746.932 | 1202.374 | ops/s
>> Poly1305DigestBench.digestBytes | 16384 | thrpt | 3 | 27626.478 | 341.915 | ops/s
>> Poly1305DigestBench.digestBytes | 1048576 | thrpt | 3 | 265.235 | 3522.458 | ops/s
>> Poly1305DigestBench.updateBytes | 64 | thrpt | 3 | 3394516.156 | 14656.687 | ops/s
>> Poly1305DigestBench.updateBytes | 256 | thrpt | 3 | 1463745.045 | 19608.937 | ops/s
>> Poly1305DigestBench.updateBytes | 1024 | thrpt | 3 | 459312.198 | 1720.655 | ops/s
>> Poly1305DigestBench.updateBytes | 16384 | thrpt | 3 | 30969.117 | 813.712 | ops/s
>> Poly1305DigestBench.updateBytes | 1048576 | thrpt | 3 | 300.773 | 3345.716 | ops/s
>> 
>> #### Results for disabled intrinsic:
>> 
>> Benchmark | (dataSize) | Mode | Cnt | Score | Error | Units
>> -- | -- | -- | -- | -- | -- | -- 
>> Poly1305DigestBench.digestBuffer | 64 | thrpt | 3 | 225424.813 | 1083.844 | ops/s
>> Poly1305DigestBench.digestBuffer | 256 | thrpt | 3 | 167848.372 | 3488.837 | ops/s
>> Poly1305DigestBench.digestBuffer | 1024 | thrpt | 3 | 81802.600 | 1839.218 | ops/s
>> Poly1305DigestBench.digestBuffer | 16384 | thrpt | 3 | 7781.049 | 1101.150 | ops/s
>> Poly1305DigestBench.digestBuffer | 1048576 | thrpt | 3 | 118.778 | 74.388 | ops/s
>> Poly1305DigestBench.digestBytes | 64 | thrpt | 3 | 23510...
>
> null has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Move wide_madd and wide_mul to macroAssembler_riscv

src/hotspot/cpu/riscv/stubGenerator_riscv.cpp line 4549:

> 4547: 
> 4548:       // Recycle registers S_0, S_1, S_2
> 4549:       regs = (regs.remaining() + S_0 + S_1 + S_2).begin();

I'm not quite sure if we need to recycle regisgters here.
Could you explain the reason? Or can we remove the recycling code here, and allocate the regsters before the loop?

src/hotspot/cpu/riscv/stubGenerator_riscv.cpp line 4556:

> 4554:       // Sum now in U_2:U_1:U_0.
> 4555:       // Dead: U_0HI, U_1HI.
> 4556:       regs = (regs.remaining() + U_0HI + U_1HI).begin();

same comment as the above recycling code.

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PR Review Comment: https://git.openjdk.org/jdk/pull/16417#discussion_r1383607474
PR Review Comment: https://git.openjdk.org/jdk/pull/16417#discussion_r1383608600