RFR: 8333583: Crypto-XDH.generateSecret regression after JDK-8329538 [v3]

[Volodymyr Paprotski]

On Mon, 17 Jun 2024 23:29:18 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

> Talking about future improvements. Is it possible to optimize reduction code by converting it to intrinsic too? Or code generated by C2 is good enough?

I had some experiments to try where I was using virtual methods to add optimizations, similar to the optimization here (i.e. the default method 'does nothing' and have just one override). 

Perhaps this issue could had been solved differently and there is something to do on the compiler side i.e. requires a specific order of optimizations.. specialize the IntegerPolynomial.setProduct() hot path for XDH field type, inline mult() from XDH field, realize that the return is always zero, which allows whatever optimizations that werent run for 4% performance. (I don't yet know enough about the C2 to be able to answer or 'fix' that)

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PR Comment: https://git.openjdk.org/jdk/pull/19728#issuecomment-2174701231