RFR: 8346664: C2: Optimize mask check with constant offset [v8]

[Emanuel Peter]

On Thu, 30 Jan 2025 14:46:06 GMT, Matthias Ernst <duke at openjdk.org> wrote:

> Done, I verified that it compiles/checks, but IR tests @require something I don't seem to have.

Thanks for doing that!

Yeah, it is actually bad style to put `@requires`, we prefer having it at the IR rule with `applyIf` statements so that result verification can still happen everywhere. If you want (optional!) you could move the constraints to the `IR` rules, but the issue is that the `PopulateIndex` vectors can only be generated with SVE and AVX2 support. So that might have limited benefits at this stage. This let's me guess that you are probably working on a regular aarch64 machine with only NEON support, correct?

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PR Comment: https://git.openjdk.org/jdk/pull/22856#issuecomment-2624805448