RFR: 8333867: SHA3 performance can be improved

[Vladimir Kozlov]

On Mon, 10 Jun 2024 15:01:55 GMT, Ferenc Rakoczi <duke at openjdk.org> wrote:

> This PR removes some unnecessary conversions between byte arrays and long arrays during SHA3 digest computations.

src/java.base/share/classes/sun/security/provider/SHA3.java line 100:

> 98:         b2lLittle(b, ofs, longBuf, 0, blockSize);
> 99:         for (int i = 0; i < blockSize / 8; i++) {
> 100:             state[i] ^= longBuf[i];

Clever. So the intrinsic (C2 code) still generates code corresponding original loop with `byte b[]` array. This will be confusing. It will also slowdown execution in Interpreter so - additional array copy.

New code also assumes that `buffer.length == blockSize` and `(buffer.length % 8) == 0`. I hope there is some assertions/checks in java code to verify that.

Some one from core-libs have to review this.

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PR Review Comment: https://git.openjdk.org/jdk/pull/19632#discussion_r1633688295