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

[vish-chan]

Clean backport of 8369881: C2: Unexpected node in SuperWord truncation: ReverseBytesS, ReverseBytesUS

Fixes fuzzer-discovered assert failure in SuperWord truncation for ReverseBytesS and ReverseBytesUS nodes. Adds missing nodes to truncation switch statement and includes test cases for both.

Additional Testing:

• New regression test fails without the fix, passes with it.
• Linux x86_64 server fastebug compiler tests.

---

Progress

• Change must not contain extraneous whitespace
• JDK-8369881 needs maintainer approval
• Commit message must refer to an issue

Issue

• JDK-8369881: C2: Unexpected node in SuperWord truncation: ReverseBytesS, ReverseBytesUS (Bug - P3 - Requested)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk25u-dev.git pull/233/head:pull/233
$ git checkout pull/233

Update a local copy of the PR:
$ git checkout pull/233
$ git pull https://git.openjdk.org/jdk25u-dev.git pull/233/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 233

View PR using the GUI difftool:
$ git pr show -t 233

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk25u-dev/pull/233.diff

Using Webrev

Link to Webrev Comment

[bridgekeeper]

👋 Welcome back vish-chan! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

❗ This change is not yet ready to be integrated.
See the Progress checklist in the description for automated requirements.

[openjdk]

This backport pull request has now been updated with issue from the original commit.

[openjdk]

⚠️ @vish-chan This change is now ready for you to apply for maintainer approval. This can be done directly in each associated issue or by using the /approval command.

[mlbridge]

Webrevs

• 00: Full (67881f24)

[vish-chan]

/approval request for Clean backport of 8369881: C2: Unexpected node in SuperWord truncation: ReverseBytesS, ReverseBytesUS

This is a low risk fix adding 2 missing node types to Superword non-truncation list. Fixes debug assert failure with no impact in product.

[openjdk]

@vish-chan
8369881: The approval request has been created successfully.