RFR: 8317721: RISC-V: Implement CRC32 intrinsic

[Hamlin Li]

On Mon, 11 Dec 2023 15:56:24 GMT, ArsenyBochkarev <duke at openjdk.org> wrote:

> Performance comparison for disabling/enabling Zba on StarFive VisionFive 2 board:
> 
`-XX:-UseZba`:

Benchmark	(count)	Mode	Cnt	Score	Error	Units

CRC32.TestCRC32.testCRC32Update	512	thrpt	12	512.550	1.718	ops/ms
CRC32.TestCRC32.testCRC32Update	2048	thrpt	12	130.396	0.341	ops/ms
CRC32.TestCRC32.testCRC32Update	16384	thrpt	12	16.319	0.073	ops/ms
CRC32.TestCRC32.testCRC32Update	65536	thrpt	12	3.913	0.011	ops/ms


`-XX:+UseZba`:

Benchmark	(count)	Mode	Cnt	Score	Error	Units

CRC32.TestCRC32.testCRC32Update	512	thrpt	12	623.173	0.651	ops/ms
CRC32.TestCRC32.testCRC32Update	2048	thrpt	12	158.965	0.376	ops/ms
CRC32.TestCRC32.testCRC32Update	16384	thrpt	12	19.934	0.055	ops/ms
CRC32.TestCRC32.testCRC32Update	65536	thrpt	12	4.730	0.007	ops/ms


`-XX:-UseCRC32Intrinsics`:

Benchmark	(count)	Mode	Cnt	Score	Error	Units

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



Seems there is regression when `count >= 512`, especially when `count >= 2048`. And I suppose that big message is common case for CRC32 usage?

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PR Comment: https://git.openjdk.org/jdk/pull/17046#issuecomment-1867505012