RFR: 8248188: Add IntrinsicCandidate and API for Base64 decoding [v9]

Tue Nov 3 02:55:58 UTC 2020

On Mon, 26 Oct 2020 19:22:23 GMT, Paul Murphy <github.com+12972156+pmur at openjdk.org> wrote:

>> Just to make sure I understand, you're not asking for a change here, is that right?
>
> I think the first line should also express the initial layout of the 6 bit values similar to the linked algo.  I think changing this comment add an extra line which describes the bits as they leave `vaddubm` would be helpful to understand the demangling here. (e.g the `00aaaaaa 00bbbbbb 00ccccc 00dddddd` comments in the linked paper)

I think I have addressed the issues in this comment with the latest commits.  Reversing the order of the bytes in the tables seems to make the tables easier to understand, and also make the vector constant declarations consistent: all use the ARRAY_TO_LXV_ORDER macro now.

The 00aaaaa (etc.) bit fields are added to the tables..  I'm not 100% sure they help much, but at least the comments follow the original paper in a clearer way.

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PR: https://git.openjdk.java.net/jdk/pull/293