RFR: 8338124: C2 SuperWord: MulAddS2I input permutation still partially broken after JDK-8333840

[Vladimir Kozlov]

On Mon, 12 Aug 2024 07:17:22 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

> [JDK-8333840](https://bugs.openjdk.org/browse/JDK-8333840) attempted to fix some input permutation cases. Sadly, there is a typo which means that there can still be some broken cases that produce wrong results.
> 
> `MulAddS2I` is a special case, where we have to verify that the 4 inputs for all members of the pack are in the same permutation. I only started the checking on the second element. This worked on all my previous examples, but does not work on the added regression test. We must, of course, start the checking on the first element.

Good.

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Marked as reviewed by kvn (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/20539#pullrequestreview-2233629728