RFR: 8316592: RISC-V: implement poly1305 intrinsic [v3]

[null]

> 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 | 235107.377 | 16410.542 | ops/s
> Poly1305DigestBench.digestBytes | 256 | thrpt | 3 ...

null has updated the pull request incrementally with one additional commit since the last revision:

  Replace slli/add sequence with shadd instruction

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/16417/files
  - new: https://git.openjdk.org/jdk/pull/16417/files/359f1265..99a4b098

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=16417&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=16417&range=01-02

  Stats: 8 lines in 1 file changed: 0 ins; 4 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/16417.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16417/head:pull/16417

PR: https://git.openjdk.org/jdk/pull/16417