RFR: 8369881: C2: Unexpected node in SuperWord truncation: ReverseBytesS, ReverseBytesUS

[Christian Hagedorn]

On Wed, 15 Oct 2025 08:46:23 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

> The fuzzer found the `ReverseByteS` case, and I checked all other `*.reverseBytes`, and found a failure with `Character.reverseBytes` as well.
> 
> Adding them to the list, and added tests for both.
> 
> Note, this is just another 2 boxes checked, there were many similar ones fixed, or on the way:
> https://github.com/openjdk/jdk/pull/26827
> https://github.com/openjdk/jdk/pull/26334
> https://github.com/openjdk/jdk/pull/26494
> https://github.com/openjdk/jdk/pull/26423

Looks good, thanks for fixing this!

test/hotspot/jtreg/compiler/vectorization/TestSubwordTruncation.java line 355:

> 353: 
> 354:     @Test
> 355:     @IR(counts = { IRNode.STORE_VECTOR, "=0" })

You could use `failOn` instead. Same below.

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Marked as reviewed by chagedorn (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/27819#pullrequestreview-3339283808
PR Review Comment: https://git.openjdk.org/jdk/pull/27819#discussion_r2431780805