[jdk18u] RFR: 8283451: C2: assert(_base == Long) failed: Not a Long

[Tobias Hartmann]

Backport of [JDK-8283451](https://bugs.openjdk.java.net/browse/JDK-8283451). Applies cleanly. Approval is pending.

Thanks,
Tobias

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Commit messages:
 - 8283451: C2: assert(_base == Long) failed: Not a Long

Changes: https://git.openjdk.java.net/jdk18u/pull/60/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk18u&pr=60&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8283451
  Stats: 80 lines in 2 files changed: 78 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk18u/pull/60.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk18u pull/60/head:pull/60

PR: https://git.openjdk.java.net/jdk18u/pull/60