[jdk17u-dev] RFR: 8268276: Base64 Decoding optimization for x86 using AVX-512 [v3]

[Derek White]

On Mon, 31 Oct 2022 20:26:26 GMT, Scott Gibbons <duke at openjdk.org> wrote:

>> This is a backport of JDK-8268276: Base64 Decoding optimization for x86 using AVX-512.
>> 
>> We have had numerous customer requests for this functionality to be backported due to the ~19x performance improvement.
>>  
>> Original patch does not apply cleanly to 17u, because of a bug that was identified in the original commit, but not fixed until the later Base64 Encode acceleration enhancement was complete.  The fix is on line 6039 of src/hotspot/cpu/x86/stubGenerator_x86_64.cpp and has been included in this PR.  All four "translatedX" registers needed to be checked for illegal characters in the input stream.
>> 
>> Risk: I view the risk of this backport to be minimal.  This code has been in use for many months with no bugs reported.
>>  
>> Testing: x86_64 build, affected tests, tier1, tier2
>>  
>> Thanks,
>> --Scott
>
> Scott Gibbons has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - Merge branch 'Decode-backport' of https://github.com/asgibbons/jdk17u-dev into Decode-backport
>  - Hand-merging bugfix 9a1bbaf8db0e869ab76be8ab1bd0ddeb23693e7e

This looks good to me. Still need a (R)eviewer.

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PR: https://git.openjdk.org/jdk17u-dev/pull/840