RFR: 8337666: AArch64: SHA3 GPR intrinsic [v2]

[Dmitry Chuyko]

On Fri, 30 May 2025 18:21:39 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 with a new target base due to a merge or a rebase. The pull request now contains five commits:
> 
>  - Copyright year
>  - Review suggestions
>  - Merge master
>  - Delete empty line
>  - SHA3 GPR intrinsic & tests

GPR rol, rax and rax1 pseudo instructions were added in MacroAssembler.

Main loop and "bcax"/Chi parts were extracted as functions.

Main loop counter was put in fp register with fp decrement and fcmp (this variant does have a positive impact).

Updated results from Graviton machines (Linux, intrinsic vs C2):

Benchmark              (digesterName)  (length)  Pct
G2
MessageDigests.digest        SHA3-256        64     +20.8%
MessageDigests.digest        SHA3-256     16384     +27.2%
G3
MessageDigests.digest        SHA3-256        64     +12.8%
MessageDigests.digest        SHA3-256     16384     +15.7%
G4
MessageDigests.digest        SHA3-256        64     +9.7%
MessageDigests.digest        SHA3-256     16384     +13.2%

-------------

PR Comment: https://git.openjdk.org/jdk/pull/24260#issuecomment-2923102950