RFR: 8337666: AArch64: SHA3 GPR intrinsic [v7]
Emanuel Peter
epeter at openjdk.org
Wed Jun 4 08:24:24 UTC 2025
On Tue, 3 Jun 2025 16:31:08 GMT, Dmitry Chuyko <dchuyko at openjdk.org> wrote:
>> This is an implementation of SHA3 intrinsics for AArch64 that operates GPRs. It follows the Java implementation algorithm but eagerly uses available registers. For example, FP+R18 are used when it's allowed. On simpler cores like RPi3 or Surface Pro it is 23-53% faster than C2 compiled version; on Graviton 3 it is 8-14% faster than C2 compiled version (which is faster than the current intrinsic); on Apple Silicon it is faster than C2 compiled version but slower than the ARMv8.2-SHA intrinsic. Improvements on a particular CPU depend on the input length. For instance, for Graviton 2:
>>
>>
>> Benchmark (ops/ms) (digesterName) (length) G2
>> MessageDigests.digest SHA3-256 64 28.28%
>> MessageDigests.digest SHA3-256 16384 53.58%
>> MessageDigests.digest SHA3-512 64 27.97%
>> MessageDigests.digest SHA3-512 16384 43.90%
>> MessageDigests.getAndDigest SHA3-256 64 26.18%
>> MessageDigests.getAndDigest SHA3-256 16384 52.82%
>> MessageDigests.getAndDigest SHA3-512 64 24.73%
>> MessageDigests.getAndDigest SHA3-512 16384 44.31%
>>
>>
>> (results for intermediate input lengths look like steps)
>>
>> On Graviton 4 there is still a noticeable difference between the proposed implementation and C2 generated code:
>>
>>
>> Benchmark (digesterName) (length) Pct
>> MessageDigests.digest SHA3-256 64 8.3%
>> MessageDigests.digest SHA3-256 16384 11%
>> MessageDigests.digest SHA3-512 64 8.4%
>> MessageDigests.digest SHA3-512 16384 11.5%
>> MessageDigests.getAndDigest SHA3-256 64 7.2%
>> MessageDigests.getAndDigest SHA3-256 16384 11%
>> MessageDigests.getAndDigest SHA3-512 64 7.3%
>> MessageDigests.getAndDigest SHA3-512 16384 11.6%
>>
>>
>> and the version that uses the extension is ~1.8x slower than C2
>>
>> Existing intrinsic implementation is put under a flag `UseSIMDForSHA3Intrinsic` which is on by default where the intrinsic is enabled currently.
>>
>> Sanity tests were modified to cover new intrinsic variants (`-XX:-UseSIMDForSHA3Intrinsic -XX:+-PreserveFramePointer`) on aarch64 hw. Existing test cases where intrinsic is enabled are executed with `-XX:+IgnoreUnrecognizedVMOptions -XX:+UseSIMDForSHA3Intrinsic`, on platforms where the sha3 extension is missing they still are cut off by isSHA3IntrinsicAvailable() predicate.
>>
>> The original PR https://github.com/openjdk/jdk/pull/20422 has been auto-closed and the branch has...
>
> Dmitry Chuyko has updated the pull request incrementally with one additional commit since the last revision:
>
> No imm masking in rolw
A nit: can you please fix the alignment issue in the PR description's benchmark results?
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PR Comment: https://git.openjdk.org/jdk/pull/24260#issuecomment-2939083282
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