[jdk17u-dev] RFR: 8284358: Unreachable loop is not removed from C2 IR, leading to a broken graph

[Goetz Lindenmaier]

I backport this for parity with 17.0.5-oracle.

-------------

Commit messages:
 - Backport 95497772e7207b5752e6ecace4a6686df2b45227

Changes: https://git.openjdk.org/jdk17u-dev/pull/599/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=599&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8284358
  Stats: 289 lines in 2 files changed: 250 ins; 3 del; 36 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/599.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev pull/599/head:pull/599

PR: https://git.openjdk.org/jdk17u-dev/pull/599