[jdk21u] RFR: 8314024: SIGSEGV in PhaseIdealLoop::build_loop_late_post_work due to bad immediate dominator info

Fri Sep 1 09:01:03 UTC 2023

Clean backport.
Tests in compiler/loopopts are passed.

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Commit messages:
 - Backport ed1ea5fe7c6fad03ca96e7dece2127eab21a608a

Changes: https://git.openjdk.org/jdk21u/pull/124/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk21u&pr=124&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8314024
  Stats: 83 lines in 3 files changed: 83 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk21u/pull/124.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u.git pull/124/head:pull/124

PR: https://git.openjdk.org/jdk21u/pull/124