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

Scott Gibbons github.com+6704669+asgibbons at openjdk.java.net
Tue Jun 8 16:13:19 UTC 2021


On Tue, 8 Jun 2021 14:13:53 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

>> I must be missing something.  How is the brute force loop aligned if not by this directive?  I don't see an alignment anywhere else that could force it.  After the entry(), there are pushes and length comparisons followed by the conditional on VBMI.  The only thing I can guess would be that the jmp aligns, but I see no indication that that occurs.
>> 
>> Perhaps what you missed was that L_forceLoop is aligned (line 6288).  This is not the same label as L_bruteForce, which is a jump target from within the VBMI conditional (which should be aligned)?  Otherwise, I don't see how L_bruteForce could possibly already be aligned.
>
> Yes, I meant force loop already has alignment so earlier one can  be removed.

Sorry - still confused.  These are two different labels, bound to two different locations.  I believe the alignments for both are justified.

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PR: https://git.openjdk.java.net/jdk/pull/4368


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