RFR: 8343689: AArch64: Optimize MulReduction implementation [v11]

Wed Sep 10 15:57:54 UTC 2025

On Tue, 9 Sep 2025 06:51:00 GMT, Xiaohong Gong <xgong at openjdk.org> wrote:

> Do you intend to ignore ops with >32B vector size? May I ask the reason?

The reason is the lack of relevant hardware. The only publicly available platform that implements 512b SVE I'm aware of is Fujitsu A64FX. I used to have access to that platform but no longer which makes it difficult to test and benchmark changes for 512b SVE. Stripping that functionality and keeping the implementation in bounds of 256b SVE reduces complexity of this patch.

> If so, maybe the title like AArch64: Implement MulReduction for 256-bit SVE is more accurate?

Given the state of the PR it might be. Thank you for the suggestion, I'll consider it.

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PR Comment: https://git.openjdk.org/jdk/pull/23181#issuecomment-3275566957