RFR: 8317721: RISC-V: Implement CRC32 intrinsic [v11]

[ArsenyBochkarev]

On Tue, 2 Apr 2024 16:07:27 GMT, ArsenyBochkarev <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#L4224) `_updateBytesCRC32`, `_updateByteBufferCRC32` and `_updateCRC32` intrinsics. This patch introduces only the plain (non-vectorized, no Zbc) version.
>> 
>> ### Correctness checks
>> 
>> Tier 1/2 tests are ok.
>> 
>> ### Performance results on T-Head board
>> 
>> #### Results for enabled intrinsic:
>> 
>> Used test is `test/micro/org/openjdk/bench/java/util/TestCRC32.java`
>> 
>> | Benchmark                                             |  (count) |  Mode | Cnt    | Score |   Error |  Units |
>> | --- | ---- | ----- | --- | ---- | --- | ---- |
>> | CRC32.TestCRC32.testCRC32Update  |     64  | thrpt     | 24 | 3730.929 | 37.773 | ops/ms |
>> | CRC32.TestCRC32.testCRC32Update  |    128 |  thrpt    | 24 | 2126.673 |  2.032 | ops/ms |
>> | CRC32.TestCRC32.testCRC32Update  |    256 | thrpt    |  24 | 1134.330 |  6.714 | ops/ms |
>> | CRC32.TestCRC32.testCRC32Update  |    512 | thrpt    |  24 |  584.017 |  2.267 | ops/ms |
>> | CRC32.TestCRC32.testCRC32Update  |   2048 |  thrpt   |   24 |  151.173 |  0.346 | ops/ms |
>> | CRC32.TestCRC32.testCRC32Update  |   16384 | thrpt |  24 |   19.113 |  0.008 | ops/ms |
>> | CRC32.TestCRC32.testCRC32Update  |  65536 | thrpt  | 24  |   4.647 | 0.022 | ops/ms |
>> 
>> #### Results for disabled intrinsic:
>> 
>> | Benchmark                                            | (count)  |  Mode | Cnt |   Score  |  Error   | Units     |
>> | --------------------------------------------------- | ---------- | --------- | ---- | ----------- | --------- | ---------- | 
>> | CRC32.TestCRC32.testCRC32Update |      64    |  thrpt   | 15  | 798.365 | 35.486 | ops/ms |
>> | CRC32.TestCRC32.testCRC32Update |     128   |  thrpt   | 15  | 677.756 | 46.619 | ops/ms |
>> | CRC32.TestCRC32.testCRC32Update |     256   |  thrpt   | 15  | 552.781 | 27.143 | ops/ms |
>> | CRC32.TestCRC32.testCRC32Update |     512   |  thrpt   | 15  | 429.304 | 12.518 | ops/ms |
>> | CRC32.TestCRC32.testCRC32Update |    2048  |  thrpt   | 15  | 166.738 |  0.935  | ops/ms |
>> | CRC32.TestCRC32.testCRC32Update |   16384 |  thrpt   | 15  |  25.060  | 0.034   | ops/ms |
>> | CRC32.TestCRC32.testCRC32Update |   65536 |  thrpt   | 15  |   6.196   | 0.030   | ops/ms |
>
> ArsenyBochkarev has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - Schedule instructions better
>  - Fix crc32.h path

Hello again everyone! I made two changes to this PR:
1. Now the intrinsic is Zba-exclusive.
2. I used the `slli` + `srliw` combination instead of `srli` + `andi` and rescheduled them a bit, making use of `t6` register.

Current results on StarFive VisionFive2 (with Zba) are:

| Benchmark                      |  (count)  | Mode | Cnt |    Score  |  Error |  Units |
| -------------------------------------------------- | ------- | ------- | --- | ------------ | ------- | ----------- |
| CRC32.TestCRC32.testCRC32Update  |     64 | thrpt  | 12 | 4644.129 |  9.566 | ops/ms |
| CRC32.TestCRC32.testCRC32Update  |    128 | thrpt  | 12 | 2911.927 | 12.866 | ops/ms |
| CRC32.TestCRC32.testCRC32Update  |    256 | thrpt  | 12 | 1538.630 |  5.463 | ops/ms |
| CRC32.TestCRC32.testCRC32Update  |    512 | thrpt  | 12  | 799.100 |  3.216 | ops/ms |
| CRC32.TestCRC32.testCRC32Update  |   2048 | thrpt |  12  | 205.947 |  0.236 | ops/ms |
| CRC32.TestCRC32.testCRC32Update  |  16384 | thrpt |  12  |  25.880 |  0.069 | ops/ms |
| CRC32.TestCRC32.testCRC32Update  |  65536 | thrpt  | 12 |    6.022 |  0.020 | ops/ms |

Results for disabled intrinsic on VisionFive2 (taken from [here](https://github.com/openjdk/jdk/pull/17046#issuecomment-1850364667))

| Benchmark                    |    (count) |  Mode | Cnt  |  Score  |  Error  | Units |
| ------------------------------- | ------------ | --------- | ----- | ---------| ---------- | ------ |
| CRC32.TestCRC32.testCRC32Update  |     64    | thrpt |  12 | 1390.530 | 42.217 | ops/ms |
| CRC32.TestCRC32.testCRC32Update  |    128   | thrpt |  12 | 1109.742 | 24.201 | ops/ms |
| CRC32.TestCRC32.testCRC32Update  |    256   | thrpt |  12 |  805.345  | 12.155 |  ops/ms |
| CRC32.TestCRC32.testCRC32Update  |    512   | thrpt |  12 |  520.965  |  5.651 | ops/ms |
| CRC32.TestCRC32.testCRC32Update  |   2048  | thrpt |  12 |  169.591  |  0.747 | ops/ms |
| CRC32.TestCRC32.testCRC32Update  |  16384 | thrpt |  12 |   22.624   |  0.139 | ops/ms |
| CRC32.TestCRC32.testCRC32Update  |  65536 | thrpt |  12 |    5.430    |  0.016 | ops/ms |

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

PR Comment: https://git.openjdk.org/jdk/pull/17046#issuecomment-2124965284