RFR: 8341013: Optimize x86/aarch64 MD5 intrinsics by reducing data dependency
Oli Gillespie
ogillespie at openjdk.org
Thu Sep 26 13:47:37 UTC 2024
On Thu, 26 Sep 2024 11:33:00 GMT, Oli Gillespie <ogillespie at openjdk.org> wrote:
> As suggested in https://github.com/animetosho/md5-optimisation?tab=readme-ov-file#dependency-shortcut-in-g-function, we can delay the dependency on 'b' by recognizing that the ((d & b) | (~d & c)) is equivalent to ((d & b) + (~d & c)) in this scenario, and we can perform those additions independently, leaving our dependency on b to the final addition. This speeds it up around 5%.
>
> Benchmark results on my two hosts:
>
>
> Benchmark (algorithm) (dataSize) (provider) Mode Cnt Score Error Units
>
> x86 Before:
> MessageDigestBench.digest MD5 1048576 thrpt 10 636.389 ± 0.240 ops/s
>
> x86 After:
> MessageDigestBench.digest MD5 1048576 thrpt 10 671.611 ± 0.226 ops/s (+5.5%)
>
>
> aarch64 Before:
> MessageDigestBench.digest MD5 1048576 thrpt 10 498.613 ± 0.359 ops/s
>
> aarch64 After:
> MessageDigestBench.digest MD5 1048576 thrpt 10 526.008 ± 0.491 ops/s (+5.6%)
Looks like there's a bug, at least on macos aarch64. I will investigate.
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PR Comment: https://git.openjdk.org/jdk/pull/21203#issuecomment-2377021394
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