RFR: 8248188: Add IntrinsicCandidate and API for Base64 decoding [v4]

[Martin Doerr]

On Mon, 12 Oct 2020 22:00:24 GMT, CoreyAshford <github.com+51754783+CoreyAshford at openjdk.org> wrote:

>> This latest push passes the intrinsic regression test. I had run the intrinsic TestBase64 regression test on the
>> previous push, but not the one in utils.  Interesting.  Somehow it didn't occur to me that there could be a problem
>> there if the intrinsic TestBase64 test passed.  I will check into the other regression test.  Don't review this latest
>> push just yet.
>
> Ok, all is clear.  I just ran `jdk/java/util/Base64/TestBase64.java` which passes as well.  Please review again when
> convenient.

Hi Corey,

thanks for taking some stuff out of the “too short” path.
There may be a performance regression when decoding many short arrays because of the stub call overhead and the usage
of the slower part of the Java implementation.

We could do it a little better in many cases to compute the maximum possible iteration count i:
i = (sl - sp) / block_size
if (i * block_size > sl - 12) i--
if (i <= 0) return 0
What do you think?

I don’t think branch prediction hints are helpful for the “too short” check.

And we should better use CCR1 instead of CCR2 which is specified as non-volatile.

Did you already find a 2nd reviewer for the PPC64 part?

Best regards,
Martin



From: CoreyAshford <notifications at github.com>
Sent: Dienstag, 13. Oktober 2020 00:01
To: openjdk/jdk <jdk at noreply.github.com>
Cc: Doerr, Martin <martin.doerr at sap.com>; Mention <mention at noreply.github.com>
Subject: Re: [openjdk/jdk] 8248188: Add IntrinsicCandidate and API for Base64 decoding (#293)


Ok, all is clear. I just ran jdk/java/util/Base64/TestBase64.java which passes as well. Please review again when
convenient.

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