RFR: 8371820: Further AES performance improvements for key schedule generation

[Shawn M Emery]

On Thu, 13 Nov 2025 16:49:34 GMT, Martin Doerr <mdoerr at openjdk.org> wrote:

>> This fix simplifies the hotspot intrinsics for some platforms and optimizes the key computation for encryption. We can save the `genInvRoundKeys` computation when we only do encryption.
>> 
>> The micro:org.openjdk.bench.javax.crypto.AESReinit benchmark results are improved by 17% for ppc64 and 26% for x86_64.
>
> @smemery: I've seen your recent improvements and performance measurements. It would be great if you could take a look at this proposal and check the performance results in your environment.

@TheRealMDoerr: I've ran your update of the init key schedule w/intrinsics logic and obtained the following results for AESReinit:
x86_64:  19.51% improvement
arm64: 3.11% improvement
Changes in performance for the other AES-related benchmarks (AES[Decrypt].testBaseline and AESBench) had the expected nominal changes.
AES regression tests (Cipher/AES and hotspot/*/aes) have passed.

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

PR Comment: https://git.openjdk.org/jdk/pull/28299#issuecomment-3531238034