RFR: 8370863: VectorAPI: Optimize the VectorMaskCast chain in specific patterns [v5]

[Emanuel Peter]

On Fri, 26 Dec 2025 11:09:30 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>> Hi @eme64 , I’d really appreciate hearing your thoughts on this when you have a moment.
>
> Honestly, I'd just make it an assert, if your code currently does not expect it.

That will force us to look at the example that would eventually violate the assert, and evaluate the situation. Maybe it would reveal a bug (and we could catch and fix it). Maybe it is a new pattern that means we have to rethink things more widely. Or maybe we'd just convert it back to a condition, but at least at that point we'd have an example that takes the other branch.

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PR Review Comment: https://git.openjdk.org/jdk/pull/28313#discussion_r2648050276