RFR: 8354242: VectorAPI: combine vector not operation with compare [v2]

[Emanuel Peter]

On Sun, 27 Apr 2025 10:09:48 GMT, erifan <duke at openjdk.org> wrote:

>> I don't see XorVMask implemented on all non-x86 target, like PPC etc..
>
> This is not specifically required on x86, but because this test fails on x86 when `-XX:UseAVX=0` is specified. When `-XX:UseAVX=0` is specified, the sub-graph is like this:
> `(XorV (VectorMaskCmp (LoadVector ...)) (Replicate -1))`
> It is not an optimization pattern supported by this patch because we don't know what's the comparison op.

I would also prefer if you added the IR restrictions rather than the JTREG requires.
The benefit is that we can still run the tests on all platforms, at least for result verification.

Imagine someone adds optimizations to a new platform, but does not know about this test here. They make a mistake, and there is a bug, leading either to a crash or wrong result. With the requires, you test would never even run, and we would not catch it. With the IR applyIf, we would catch the bug.

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PR Review Comment: https://git.openjdk.org/jdk/pull/24674#discussion_r2062988123