[jdk18u] RFR: 8275337: C1: assert(false) failed: live_in set of first block must be empty

[Tobias Hartmann]

Backport of [JDK-8275337](https://bugs.openjdk.java.net/browse/JDK-8275337). Applies cleanly. Approval is pending.

Thanks,
Tobias

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Commit messages:
 - 8275337: C1: assert(false) failed: live_in set of first block must be empty

Changes: https://git.openjdk.java.net/jdk18u/pull/57/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk18u&pr=57&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8275337
  Stats: 71 lines in 2 files changed: 70 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk18u/pull/57.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk18u pull/57/head:pull/57

PR: https://git.openjdk.java.net/jdk18u/pull/57