8361117: SIGSEGV in LShiftLNode::Ideal due to unexpected dead node

[TheRealMDoerr]

This is a new fix for JDK-8361117 for OpenJDK. I can't see the corresponding fix because it's not public.

This fix is taken from openjdk/jdk@05a0a71.
The problem is described in https://github.com/openjdk/jdk/blob/674cc3eeca77f1f2a6d937b1df5c5cd8a13c2d31/test/hotspot/jtreg/compiler/arraycopy/TestACSameSrcDst.java#L87 but that regression test didn't reproduce the issue in jdk17u.

I've taken the reproducer from the issue and put it into a new regression test. The VM crashes without the fix and the test passes with the fix.

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Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace
• Commit message must refer to an issue
• JDK-8361117 needs maintainer approval

Issue

• JDK-8361117: SIGSEGV in LShiftLNode::Ideal due to unexpected dead node (Bug - P2)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk17u-dev.git pull/4204/head:pull/4204
$ git checkout pull/4204

Update a local copy of the PR:
$ git checkout pull/4204
$ git pull https://git.openjdk.org/jdk17u-dev.git pull/4204/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 4204

View PR using the GUI difftool:
$ git pr show -t 4204

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk17u-dev/pull/4204.diff

Using Webrev

Link to Webrev Comment

[bridgekeeper]

👋 Welcome back mdoerr! 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 the original issue, but not the original commit. If you have the original commit hash, please update the pull request title with Backport <hash>.

[mlbridge]

Webrevs

• 00: Full (40c63e86)

[TheRealMDoerr]

@rwestrel: Do you want to review?