RFR: 8351412: Add AVX-512 intrinsics for ML-KEM [v4]

[Sandhya Viswanathan]

On Wed, 14 May 2025 11:41:30 GMT, Ferenc Rakoczi <duke at openjdk.org> wrote:

>> src/hotspot/cpu/x86/stubGenerator_x86_64_kyber.cpp line 696:
>> 
>>> 694: address generate_kyberAddPoly_2_avx512(StubGenerator *stubgen,
>>> 695:                                        MacroAssembler *_masm) {
>>> 696: 
>> 
>> The Java code for "implKyberAddPoly(short[] result, short[] a, short[] b)" does BarrettReduction but the intrinsic code here does not. Is that intentional and how is the reduction handled?
>
> Actually, the Java version is the one that is too cautious. There is Barrett reduction after at most 4 consecutive uses of mlKemAddPoly(), so doing the reduction in implKyberAddPoly() is not necessary. Thanks for discovering this!

Thanks. I have another question, is there a reason that the Java versions of AddPoly (both for 2 and 3 input) return 1, whereas the corresponding intrinsics return 0?

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PR Review Comment: https://git.openjdk.org/jdk/pull/24953#discussion_r2089278218