RFR: 8358032: Use crypto pmull for CRC32/CRC32C intrinsics on Ampere CPU [v2]

[Andrew Haley]

On Wed, 4 Jun 2025 08:42:58 GMT, Andrew Haley <aph at openjdk.org> wrote:

>> Liming Liu has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Make it be a diagnostic flag
>
> src/hotspot/cpu/aarch64/macroAssembler_aarch64.cpp line 4355:
> 
>> 4353:     add(buf, buf, 32);
>> 4354:     crc32x(crc, crc, tmp2);
>> 4355:     subs(len, len, 32);
> 
> What is the point of these changes?

To be more precise: converting these adjustments to post-increment operations isn't obviously an improvement on AArch64 generally. How does it help?

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

PR Review Comment: https://git.openjdk.org/jdk/pull/25609#discussion_r2126044000