RFR: 8333867: SHA3 performance can be improved [v2]

[Valerie Peng]

On Fri, 14 Jun 2024 09:47:31 GMT, Ferenc Rakoczi <duke at openjdk.org> wrote:

>> src/java.base/share/classes/sun/security/provider/SHA3.java line 73:
>> 
>>> 71:     // The following array is allocated to size WIDTH bytes, but we only
>>> 72:     // ever use the first blockSize bytes it (for bytes <-> long conversions)
>>> 73:     private byte[] byteState = new byte[WIDTH];
>> 
>> Since we are storing the state in longs now, this "byte <-> long" conversion can be made through a local variable, right? Is there a reason for having this `byteState` field with size WIDTH bytes?
>
> This is interesting: if I use WIDTH (or in blockSize) long arrays in the local level, the performance drops a few per cents. Even more when I only declare the local array in the block in which it is used. However, since we really only need 8 bytes, if I allocate that at the beginning of the function, I don't see that performance drop. So I rewrote the output loop in the function and got rid of the class level declaration.

Interesting...
Good that we go with the local 8-byte approach, it improves the readability also.

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PR Review Comment: https://git.openjdk.org/jdk/pull/19632#discussion_r1640166504