RFR: 8354242: VectorAPI: combine vector not operation with compare [v8]

[erifan]

On Wed, 11 Jun 2025 05:31:00 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

> You are checking IRNode.XOR_VL, "= 0". But you are comparing floats. Does that make sense?

The bottom types of `float` and `double` vector masks are casted to `int` and `long`. Seems this is by design? So this is correct.

As for `control test`, yes for now I didn't add any such kind of test, because I personally think it's unnecessary. For specific code, it won't trigger this optimization now, but new optimizations in the future may cause this test to fail.

Anyway I've tested the case where `vectormaskcmp` is multi used locally, and this optimization won't be triggered. 

Do you think it's necessary to add such a control test?

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PR Review Comment: https://git.openjdk.org/jdk/pull/24674#discussion_r2139512969