RFR: 8328264: AArch64: remove UseNeon condition in CRC32 intrinsic [v2]

[Andrew Haley]

On Tue, 19 Mar 2024 15:32:31 GMT, Hamlin Li <mli at openjdk.org> wrote:

>> Hi,
>> Can you review the simple patch?
>> Thanks
>> 
>> FYI: Discussed https://github.com/openjdk/jdk/pull/18294#issuecomment-1997727704, this usage of UseNeon flag should be removed, as neon is working by default, and UseNeon could be false, so this means the intrinsic code of Neon can be skipped unexpected.
>> 
>> ## Performance
>> Tested jmh `TestCRC32` with "-XX:-UseCRC32 -XX:-UseCryptoPmullForCRC32" 
>> Before
>> 
>> Benchmark                    (count)  Mode  Cnt      Score   Error  Units
>> TestCRC32.testCRC32Update         64  avgt    2     53.696          ns/op
>> TestCRC32.testCRC32Update        128  avgt    2    104.942          ns/op
>> TestCRC32.testCRC32Update        256  avgt    2    207.147          ns/op
>> TestCRC32.testCRC32Update        512  avgt    2    411.179          ns/op
>> TestCRC32.testCRC32Update       2048  avgt    2   1608.388          ns/op
>> TestCRC32.testCRC32Update      16384  avgt    2  12763.513          ns/op
>> TestCRC32.testCRC32Update      65536  avgt    2  51024.246          ns/op
>> 
>> 
>> After
>> 
>> Benchmark                    (count)  Mode  Cnt      Score   Error  Units
>> TestCRC32.testCRC32Update         64  avgt    2     40.172          ns/op
>> TestCRC32.testCRC32Update        128  avgt    2     56.754          ns/op
>> TestCRC32.testCRC32Update        256  avgt    2     89.743          ns/op
>> TestCRC32.testCRC32Update        512  avgt    2    156.726          ns/op
>> TestCRC32.testCRC32Update       2048  avgt    2    579.776          ns/op
>> TestCRC32.testCRC32Update      16384  avgt    2   4624.023          ns/op
>> TestCRC32.testCRC32Update      65536  avgt    2  18505.180          ns/op
>
> Hamlin Li has updated the pull request incrementally with one additional commit since the last revision:
> 
>   revert indents

OK. Trivial and good.

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

Marked as reviewed by aph (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/18328#pullrequestreview-1946885966