[jdk21u-dev] RFR: 8322726: C2: Unloaded signature class kills argument value

[Martin Doerr]

Clean backport of [JDK-8322726](https://bugs.openjdk.org/browse/JDK-8322726).

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

Commit messages:
 - Backport fa02667d838f08cac7d41dfb4c3e8056ae6165cc

Changes: https://git.openjdk.org/jdk21u-dev/pull/659/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=659&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8322726
  Stats: 181 lines in 5 files changed: 168 ins; 0 del; 13 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/659.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/659/head:pull/659

PR: https://git.openjdk.org/jdk21u-dev/pull/659