RFR: 8347606: Optimize Java implementation of ML-DSA

[Bernd]

On Fri, 14 Feb 2025 16:43:32 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%.

src/java.base/share/classes/sun/security/provider/ML_DSA.java line 1237:

> 1235:         return res;
> 1236:     }
> 1237: 

Centralizing the allocation into a helper on its own Looks unseful (for resource Management, debugging/profiling and to pick the optimal implementation).

but it’s a shame that 2 dimensional allocations are sub-optimal, shouldnt that be addressed in the jvm (or c2?)

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PR Review Comment: https://git.openjdk.org/jdk/pull/23642#discussion_r1956478480