RFR: 8355563: VectorAPI: Refactor current implementation of subword gather load API [v2]

[Xiaohong Gong]

On Tue, 1 Jul 2025 18:03:33 GMT, Paul Sandoz <psandoz at openjdk.org> wrote:

> This is a nice simplification, Java changes look good. I'll let the Intel folks sign-off related to regressions. IMO minor regressions like this are acceptable if the generated code quality is good, and if the benchmark reports higher variance and averaging results from multiple forks close the gap. (In this case i don't understand how the Java changes impacts alignment).

Thanks for your review and comments @PaulSandoz ! The java changes in this patch makes the outer loop in test not be peeled as before since all the range checks or branches are hoisted out side of the loop. While it needs one iteration of loop peeling to eliminate branches before. I think this makes the whole generated code's layout changes a lot.

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PR Comment: https://git.openjdk.org/jdk/pull/25138#issuecomment-3026080127