RFR: 8372980: [VectorAPI] AArch64: Add intrinsic support for unsigned min/max reduction operations [v4]

[Andrew Haley]

On Wed, 28 Jan 2026 10:02:53 GMT, Andrew Haley <aph at openjdk.org> wrote:

>> The general way code flows right now, but not often, is from jdk/master to panama-vector/vectorIntrinsics, since most of the development work is in the mainline (exceptions to that are the float16 and Valhalla alignment work which are large efforts).
>> 
>> I am very reluctant to include all the auto-generated micro benchmarks in mainline. There is a huge number of them and i am not certain they provide as much value as they did now we have the IR test framework. In may cases, given the simplicity of what they measure, they were designed to ensure C2 generates the right instructions. The IR test framework is better at determining that by testing the right IR nodes are generated - and they get run as part of the existing HotSpot test suite.
>> 
>> The IR test framework is of course no substitute, in general, for performance tests. A better focus for Vector API performance tests is i think Emanuel's work [here](https://github.com/openjdk/jdk/pull/28639/) and use-cases/algorithms that can be implemented concisely.
>
>> The IR test framework is better at determining that by testing the right IR nodes are generated - and they get run as part of the existing HotSpot test suite.
> 
> But as a reviewer I'm not looking at the IR at all, but at the performance.

> Hi @theRealAph @PaulSandoz , thanks for your insight! How to synchronize the JMH micro benchmarks between Panama and the mainline may be a more general issue that requires further investigation, design, and resources. As for how to move this PR forward, my idea is to write a new micro benchmark in this PR to demonstrate the optimization effect of this patch. Would that be acceptable to you?

Sure.

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PR Comment: https://git.openjdk.org/jdk/pull/28693#issuecomment-3816786645