RFR: 8347606: Optimize Java implementation of ML-DSA [v3]

[Weijun Wang]

On Tue, 13 May 2025 16:49:36 GMT, Ben Perez <bperez at openjdk.org> wrote:

>> It turns out that initializing a multidimensional array with `int[][] a = new int[rows][cols]` is slower than allocating each column in a loop. Since we do a lot of large multidimensional array allocations in ML-DSA, the optimized initialization improves performance by roughly 10%.
>
> Ben Perez has updated the pull request incrementally with one additional commit since the last revision:
> 
>   remove trailing whitespace

Looks good. You might need to add a `noreg-perf` label to the JBS bug and create a comment saying how much you gained from the change. https://openjdk.org/guide/#jbs-label-dictionary requires "the bug should describe how to verify the fix". Maybe you can just say what and what tests are run.

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Marked as reviewed by weijun (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/23642#pullrequestreview-2837524239