[jdk21u-dev] RFR: 8323972: C2 compilation fails with assert(!x->as_Loop()->is_loop_nest_inner_loop()) failed: loop was transformed

[Martin Doerr]

Clean backport of [JDK-8323972](https://bugs.openjdk.org/browse/JDK-8323972).

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Commit messages:
 - Backport e1b0af29e47b46879defce1fc44c30d4d50d0c31

Changes: https://git.openjdk.org/jdk21u-dev/pull/717/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=717&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8323972
  Stats: 51 lines in 2 files changed: 50 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/717.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/717/head:pull/717

PR: https://git.openjdk.org/jdk21u-dev/pull/717