[jdk17u-dev] RFR: 8322726: C2: Unloaded signature class kills argument value [v2]

[Martin Doerr]

> Backport of [JDK-8322726](https://bugs.openjdk.org/browse/JDK-8322726). Applies cleanly, but requires two tiny adaptations (also see 2nd commit):
> 
> - `sig_type->is_loaded()` can only be used after [JDK-8275201](https://bugs.openjdk.org/browse/JDK-8275201)[JDK-8275201](https://bugs.openjdk.org/browse/JDK-8275201)[JDK-8275201](https://bugs.openjdk.org/browse/JDK-8275201) which is not in 17u. Replaced it by `sig_type->klass()->is_loaded()` which is equivalent.
> - The ClassWriter needs to write V17 compatible code.

Martin Doerr has updated the pull request incrementally with one additional commit since the last revision:

  Adaptions for JDK17.

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

Changes:
  - all: https://git.openjdk.org/jdk17u-dev/pull/2540/files
  - new: https://git.openjdk.org/jdk17u-dev/pull/2540/files/44e552eb..c2a98038

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=2540&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=2540&range=00-01

  Stats: 2 lines in 2 files changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/2540.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/2540/head:pull/2540

PR: https://git.openjdk.org/jdk17u-dev/pull/2540