RFR: 8337666: AArch64: SHA3 GPR intrinsic
Dmitry Chuyko
dchuyko at openjdk.org
Wed Mar 26 16:02:32 UTC 2025
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 been re-created on top of the new master.
-------------
Commit messages:
- Delete empty line
- SHA3 GPR intrinsic & tests
Changes: https://git.openjdk.org/jdk/pull/24260/files
Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24260&range=00
Issue: https://bugs.openjdk.org/browse/JDK-8337666
Stats: 757 lines in 5 files changed: 752 ins; 1 del; 4 mod
Patch: https://git.openjdk.org/jdk/pull/24260.diff
Fetch: git fetch https://git.openjdk.org/jdk.git pull/24260/head:pull/24260
PR: https://git.openjdk.org/jdk/pull/24260
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